IMPLEMENTING A CAD SYSTEM TO REDUCE COSTS
Introduction
This report will analyze a proposal on how Woodbridge Foam could become more competitive
through improvements in technology. This includes the saving of the companies money,
shortening the design time for new products, decreasing quoting time and improving quality
overall. By implementing a company wide CAD system, which would be networked together with
each customer and all plants, these improvements could be achieved. Research will include
interviewing various employees as to how business is done and what influences the winning or
loosing of a contract. Research will also include study of both customer and competitors
systems.
Project Scope & Current Evaluation
Goals Supported by CAD Initiative:
In converting to a completely independent CAD system, there are a few aspects of operation
which would be greatly improved. The first of the improvements would be the elimination of
paper communication. The need to transfer large drawings using mylars would cease to be,
thus helping provide a paper less environment. Another improvement as a result of CAD would
be that of achieving much tighter tolerances in building new products. Using a CAD system,
part designs could be received in an electronic format such as a math model. These models
are currently in use by customers such as GM, BMW and Mercedes. The effect of having math
models of all new products would enable a quicker turnaround in both quoting and production
of products. CAD Vendors & Hardware Suppliers: Upon observing the various systems used by
several customers and suppliers, the major CAD vendors worth consideration have been
identified. Manufacturers of high quality workstations which have been distinguish are:
Hewlett Packard (HP) IBM Silicon Graphics (SGI) SUN Premium, fully functional CAD solutions
are: CATIA (Dassault / IBM) Computervision (Computervision / TSI) SDRC (SDRC / CAD
Solutions) Unigraphics (EDS) Current System Description Success Factors: In implementing a
new, otherwise foreign system into an established habitual way of doing things, there are
several success factors which must be examined. If these factors are carefully thought
over, a favorable shift from old to new may be obtained. Some critical success factors are
as follows: Vendor availability - Will the chosen system supplier be readily available for
technical support? Product engineering acceptance - Will those who are set in their ways be
willing to abandon their habitual manner of operating? Training - Thorough training of all
related employees must be completed before introduction of the new system. Data management
- A new manner of recording all vital information must be established and proper procedures
documented. Customer interface - Will the chosen system be compatible with those used by our
customers and will needed data be easily convertible?
Company Weaknesses:
Currently, there are many aspects of our situation which present problems in coping with
changing times, which in turn affect the development of technology. Some weaknesses in the
company which curtail our affiliation with the developmental progress of our customers and
suppliers are: We cannot easily accept electronic data; We must deal in manual drawings; We
have many copies of similar drawings; We have multiple ECN levels; We have minimal CAD
knowledge; We must perform manual volume calculations.
Threats to Business:
If procedures are not taken in order to improve on the present company weaknesses, there are
bona fide threats which could potentially harm future progress and business. Once the
weakness in the company have been effaced, the following threat to our business may be
eliminated or greatly reduced. The immediate threats are: Suppliers may assume the design
role; Competitors able to accept electronic input; No business with new products;
Deterioration of communications; Lost productivity Process Description: As in most large
corporations, our process generally follows a standard order of operations. There are
several departments or areas which have functions. Based on the function of a department or
area, a focus area is established and followed. Department/Area Function Focus Area
Customer
Designs seat
Product Engineering
Designs tool to manufacture seat
Supplier
Builds tools and supplies components needed to manufacture and construct seat
Product Evaluation & Costing
Costs seat based on foam and components used, manufacturing costs and assembly
Purchasing
Locates seat component suppliers and oversees development and manufacture of components
Plant
Manufactures and assembles seat
Quality Control
Ensures that products meet our own and customer standards
Sales / Marketing
Processes orders and manages overall customer relationships
New System Requirements
CAD System Requirements:
The CAD system which is chosen must be capable of performing several specific tasks. In
order for a new system to be of any use to the company and an aid to its advancement, it
must present an improvement in various areas. Some of the short term requirement of a new
CAD system are: Capable of 3D modeling including solids; May be used for simple or complex
drafting applications; Suited to quickly perform volume calculations; Apt to translate
various forms of math data.
Product Evaluation & Costing (P.E.C.) Requirements:
With respect to all the various areas of the company, the role of the P.E.C. department is
one of the most important in the area of profit. Once the costing department receives a
part request from a customer, it is the responsibility of the costing department to ensure
that the life cycle of the part development is managed cost efficiently. When a current
product undergoes an engineering change, it is the responsibility of the Costing team
members to note the changes. The product must be re-costed, accounting for variances in
foam and components. If an increase in foam is noted, the change must be calculated. Using
manual calculations, the new part volume is derived and the customer is charged accordingly.
Because foam variances are obtained manually, customers may at times, not be fully charged
for the added cost of foam. Using a CAD system to perform a volume calculation, the answer
would be definitive. The time needed to ship a print is approximately two days. If math
models of products were sent via E-mail, the information needed by the costing department
would be obtained two days earlier. Once complete, a costing package would in turn, arrive
at a plant, also two days earlier from costing. In effect, a total of four days could be
eliminated from the time needed to begin manufacturing a product. Solution Evaluation &
Recommendation Benefits of CAD System In utilizing a CAD system, there are many areas of
operation which are directly or indirectly affected. Because of the speed and accuracy with
which a professional CAD system operates, time, and thus money, may be saved. Potential CAD
project benefits include: Improved accuracy in quotes and design; Reduction in copying and
courier costs; Faster and more accurate calculations of complex volumes; Management of
expanding drawing database; Improved electronic communication with customers and suppliers.
Recommended Vendor/Supplier
Based on thorough presentations made to executives of Woodbridge Foam by each candidate and
the penetration of these amongst key Woodbridge customers, it is recommended that
Unigraphics be implemented as the solution. The Unigraphics system is currently used b 40%
of Woodbridge customers. This system is also capable of performing all of the previously
mentioned tasks such as 3D modeling, drafting, volume calculations and translating different
forms of math data.
Justification of CAD & Unigraphics
CAD justification includes:
Elimination of Mylars;
Encouragement of a paper-less environment;
Reduction in copy and reproduction costs;
Reduction in courier costs;
Faster and more accurate part volume calculations.
Unigraphics justification includes:
Used by key customers such as Chrysler and GM;
Ability to convert data used by all customers;
Extra commitment and availability for technical support;
Extensive research into company prior to presentation.
Work Station Cost:
One time costs for one Workstation:
Unigraphics Software License
$30 000
Hewlett Packard Workstation
$45 000
EDS Assistance (Assessment/Help)
$ 5 000
Training (UG Education)
$10 000
Consulting Assistance
$ 7 500
Printer and Plotter
$30 000
Hummingbird/Exceed PC Access Software
$10 000
One time total costs
$137 500
Annual Maintenance Costs: $3 750
Cost Reductions:
As previously mentioned, the implementation of a CAD system will reduce costs in several
areas. By eliminating the need for physical prints, the cost of reproducing and shipping
prints will be eliminated. Some potential cost reductions in dollars are: Prints: 35,000
Mylars:
75,000
Courier:
5,500
Travel:
16,000
Plants (saved travel):
90,000*
Productivity Improvement
75,000*
TOTAL SAVED:
296,500
Productivity Improvements:
There are some improvements in productivity which do not present a monetary value. These
improvements however; will benefit the company and customer relations. These non-monetary
productivity improvements are: Improved accuracy; Improved customer satisfaction; Support
for higher tolerance of products; Improved on-line access to information; Improved internal
communication between Woodbridge departments.
Conclusion:
As advancements in technology continue to be the norm, it is essential that those who wish
to remain competitive, adhere to these advancements. In the case of the Woodbridge Foam
Corporation, maintaining and equal standing with technological advancements will allow for
improvements in the company as a whole. Cost saving may be incurred in the areas of print
and courier costs; while the need for paper transference is eliminated. Tolerances, quoting
time and an overall improvement in quality will in turn improve the satisfaction of our
customers. Because of these advancements in technology within the company, the saying "a
satisfied customer is a return customer" may be brought to life.
4
4
Sunday, 1 September 2013
Cyberspace in Perspective
1.
If a survey were being done on how people experience cyberspace, one would immediately notice that no two answers would be the same. Experiencing cyberspace is something that is different for every individual. I myself experience cyberspace psychologically, I experience it in my mind. There have been many attempts at trying to define the abstruse term, but up to date, no one has pinned the tail on the donkey. There cannot be one solid definition for a word that possesses so many meanings. I personally associate the word cyberspace with the idea of being able to travel to distant places without ever leaving my chair. Obviously, I know that there is no possible way of visiting different places or countries via my home computer, but in my mind, when I see the location that I am connected to, it feel as though a part of me is there. The best part is that I can switch from scenario to scenario without having to travel any ground. I do not feel a sense of distance or location, except when it takes a prolonged amount of time to connect to a host. When I travel from place to place (site to site), I do not cover any known physical distances, but instead I cover visual distance.
Just as many people do, I refer to the places that I visit as virtual worlds. I like calling them this because I never actually get to see the reality of the "world". I only get to see it electronically and digitally. The feeling that I experience while in cyberspace is knowing that I possess the power to visit any where I want. When I click one of the buttons on the mouse, or what I refer to as a transporter, I feel as though all the power in the world rests at the end of my fingertips. I am in my own sort of fantasy land. Once I land in a desired location, or website, I have the opportunity to click on pictures and words that take me to new worlds. These pictures and words have the power to make my virtual tour even more pleasing by introducing me to new and exciting things. People have referred to experiences in cyberspace, experiences such as mine, as a basic extension of the mind. I definitely agree with this statement. I believe that it takes imagination and creativity to experience all of the things that cyberspace has to offer. With all the colors, strange text and mind-boggling graphics, cyberspace is something that everyone must experience on their own. No two people experience it in the same way and it takes practice to learn different ways of experiencing all that it has to offer. I guess everyone must find their own little 'cyber-niche'.
2.
In today's technological oriented society, it is difficult for one to go about their daily lives without interacting in some form or another with digital components. Communication is the perfect example of how people interact with digital technology. Talking to loved ones who live on the other side of the globe, faxing a friend, or simply calling in sick to work, are all forms of communication, but these examples are taken for granted.
A popular form of digital communication, whether people realize it or not, is the cellular phone. Cellular phones have become very popular toys over the past few years and they are 100% digital. For people who are constantly on the go, the "Cell Phone" is a convenient digital advancement. I find the cellular phone to be of much help in the stickier situations; like when I am being forced to change a flat tire in -20o weather, when there's heavy traffic, when I want to find a quicker route to where I'm going, or when I get lost in an unfamiliar region. They are relatively expensive to use, but in most cases, I would say that they are well worth their price. I don't have five hour conversations using them, but I can let people know what I want to tell them in a short amount of time, which I find extremely handy. Before the ease of world-wide portable phones, there was a different breed of digital communication devices: beepers. Beepers, or pagers as they are commonly called, go hand in hand with cell phones. If a person does not own a cellular phone, a pager is a great alternative. It is a piece of digital equipment that allows the carrier to be notified when someone is trying to get in touch with them. I find that pagers are better in the sense that they cost less than cell phones do. I was given a pager years ago, and I still use the same one today. It's much easier to answer a pager than a cell phone when I am driving. Even though they are not as great of a communication tool as a cellular phone, I would probably never give mine up. I also communicate with the pager because I read it's LCD display when I am interested in finding out who is disturbing me.
Still on topic of communication, I cannot forget to mention television. It is a huge form of communication today, more so than ever before. Although televisions have changed dramatically in a short amount of time, TVs communicate several different messages. Everyone watches television at some point in time, and when they do, they are most likely interacting with a digital TV. I watch television for relaxation, or to keep up to date on world events. By simply changing the channels, or more complex things such as programming channels/time/date, I am interacting with the television. Television is visually pleasing. My concentration becomes affixed to the point that I have no idea, or very little idea, as to what is going on around me.
VCRs go hand in hand with the television. As I do with the TV, I have to give the VCR commands as well. Whether I tell it to PLAY, STOP or REWIND, I am interacting with it. As with the television, I am fixating all of my attention to what it is showing, or playing.
Going back to raw communication, a real piece of digital equipment that I have found to be handy is the fax machine. Fax machines transmit messages back and forth from one party to another. Fax machines are not as accessible as TVs or VCRs, but those that use them get the chance to interact with digital technology. I have found this type of digital equipment extremely useful when looking for a job. I have, in the past, faxed resumes to different employers who were looking for workers. I have also used them on many other occasions, but getting access to one is relatively difficult with out spending money to send copies. Another type of digital component that I interact with is my computer. I use it on a daily basis to type out assignments, e-mail, and to gather information off of the Internet. Also, being a student at Trent University, I have a student card which digitally allows me to take out books, eat, and get in and out of special events all by simply swiping it through a scanner. Digital pocket agendas have become quite common for students. I use one almost every time I use the phone. It contains several phone numbers, important dates, and many reminders that make organization much easier. There are many other digital components that I interact with, but I feel that the ones I have mentioned are the most prevalent in my life.
3.
Just as there are many forms of digital components that I interact with, there are many analog components as well. The most popular analog component that I use is the telephone. Some use fiberoptic lines, but I will refer to the older, more traditional phones. There are many reasons why I use the phone such as keeping in touch with family and friends, calling my boss at work, or ordering a pizza. In today's hi-tech environment, I can even call JoJo to find out what tomorrow will bring. For me, the telephone is the easiest way to get in touch with people. I find that it is much easier to express feelings over the phone for the simple fact that I do not have to be vis-à-vis with the person. Being face to face is sometimes much too personal, and I am far more interested in telling the boss that I cannot come into work without him having to see that I'm not actually sick. Therefore, it is clear that there are many reasons for using a telephone, and that these examples do not only apply to myself, but to many others who use a telephone.
Some feel that because we are in such a hi-tech world, they have to purchase the new high priced advancements. For example, buying a high quality digital watch. I think this to be very unnecessary. I own an old fashioned analog watch. The good old fashioned glow in the dark dial works best for me. I think it's just a status symbol to have the best watch, but then again, I've never seen a 24K gold digital watch. Also, when I am not listening to a CD, I still use cassette tapes. For me there is not much difference in the sound, but I can tell a difference when I want to cue (fast forward or rewind) a song. Obviously, CDs are the 'hip thing' of the 90's, but I find nothing is wrong with a cassette. There are many forms of music that I listen to that are not digital. Many people still have tape players in their vehicles, which goes to show that I am not the only person who still does not mind analog.
4.
When trying to figure out how far apart two phones are from each other, many forms of calculation come into play. It is easy to estimate that your phone is approximately thirty feet from your neighbors, but that is not very accurate, there are ways to measure the exact distance between two phones. When the police send out a signal that bounces off a moving object and then back to their radar gun, a computer program measures how long it took for the signal to come back and thus executes the calculations. A programmer could easily write a loop program that sends a signal to a far away computer (modem) and then wait for the signal to come back. This loop would allow the computer to figure out how long it took for the signal to reach it's destination, and come back, thus telling the person how far apart the two phones are from each other.
By looking at two phone numbers, one can tell by their dimensions how far apart they may be. For example, if two phones were being compared and one of the phone numbers was (519) 498-0872 and the other phone number was 011-356-7951, one might take a wild guess that these numbers are far from each other. Long distance calls, for some reason, seem to sound a little different than close connection calls. When one notices that the person on the other lines voice sounds faded or with static, they can guess that the call is coming from far away. One could get extremely technical and measure the resistance between two phones, but that is difficult for the average person to do. The easiest ways to tell how far apart two phones are is to estimate. People can estimate this by: voice quality, length of phone number, or by running a loop program.
If a survey were being done on how people experience cyberspace, one would immediately notice that no two answers would be the same. Experiencing cyberspace is something that is different for every individual. I myself experience cyberspace psychologically, I experience it in my mind. There have been many attempts at trying to define the abstruse term, but up to date, no one has pinned the tail on the donkey. There cannot be one solid definition for a word that possesses so many meanings. I personally associate the word cyberspace with the idea of being able to travel to distant places without ever leaving my chair. Obviously, I know that there is no possible way of visiting different places or countries via my home computer, but in my mind, when I see the location that I am connected to, it feel as though a part of me is there. The best part is that I can switch from scenario to scenario without having to travel any ground. I do not feel a sense of distance or location, except when it takes a prolonged amount of time to connect to a host. When I travel from place to place (site to site), I do not cover any known physical distances, but instead I cover visual distance.
Just as many people do, I refer to the places that I visit as virtual worlds. I like calling them this because I never actually get to see the reality of the "world". I only get to see it electronically and digitally. The feeling that I experience while in cyberspace is knowing that I possess the power to visit any where I want. When I click one of the buttons on the mouse, or what I refer to as a transporter, I feel as though all the power in the world rests at the end of my fingertips. I am in my own sort of fantasy land. Once I land in a desired location, or website, I have the opportunity to click on pictures and words that take me to new worlds. These pictures and words have the power to make my virtual tour even more pleasing by introducing me to new and exciting things. People have referred to experiences in cyberspace, experiences such as mine, as a basic extension of the mind. I definitely agree with this statement. I believe that it takes imagination and creativity to experience all of the things that cyberspace has to offer. With all the colors, strange text and mind-boggling graphics, cyberspace is something that everyone must experience on their own. No two people experience it in the same way and it takes practice to learn different ways of experiencing all that it has to offer. I guess everyone must find their own little 'cyber-niche'.
2.
In today's technological oriented society, it is difficult for one to go about their daily lives without interacting in some form or another with digital components. Communication is the perfect example of how people interact with digital technology. Talking to loved ones who live on the other side of the globe, faxing a friend, or simply calling in sick to work, are all forms of communication, but these examples are taken for granted.
A popular form of digital communication, whether people realize it or not, is the cellular phone. Cellular phones have become very popular toys over the past few years and they are 100% digital. For people who are constantly on the go, the "Cell Phone" is a convenient digital advancement. I find the cellular phone to be of much help in the stickier situations; like when I am being forced to change a flat tire in -20o weather, when there's heavy traffic, when I want to find a quicker route to where I'm going, or when I get lost in an unfamiliar region. They are relatively expensive to use, but in most cases, I would say that they are well worth their price. I don't have five hour conversations using them, but I can let people know what I want to tell them in a short amount of time, which I find extremely handy. Before the ease of world-wide portable phones, there was a different breed of digital communication devices: beepers. Beepers, or pagers as they are commonly called, go hand in hand with cell phones. If a person does not own a cellular phone, a pager is a great alternative. It is a piece of digital equipment that allows the carrier to be notified when someone is trying to get in touch with them. I find that pagers are better in the sense that they cost less than cell phones do. I was given a pager years ago, and I still use the same one today. It's much easier to answer a pager than a cell phone when I am driving. Even though they are not as great of a communication tool as a cellular phone, I would probably never give mine up. I also communicate with the pager because I read it's LCD display when I am interested in finding out who is disturbing me.
Still on topic of communication, I cannot forget to mention television. It is a huge form of communication today, more so than ever before. Although televisions have changed dramatically in a short amount of time, TVs communicate several different messages. Everyone watches television at some point in time, and when they do, they are most likely interacting with a digital TV. I watch television for relaxation, or to keep up to date on world events. By simply changing the channels, or more complex things such as programming channels/time/date, I am interacting with the television. Television is visually pleasing. My concentration becomes affixed to the point that I have no idea, or very little idea, as to what is going on around me.
VCRs go hand in hand with the television. As I do with the TV, I have to give the VCR commands as well. Whether I tell it to PLAY, STOP or REWIND, I am interacting with it. As with the television, I am fixating all of my attention to what it is showing, or playing.
Going back to raw communication, a real piece of digital equipment that I have found to be handy is the fax machine. Fax machines transmit messages back and forth from one party to another. Fax machines are not as accessible as TVs or VCRs, but those that use them get the chance to interact with digital technology. I have found this type of digital equipment extremely useful when looking for a job. I have, in the past, faxed resumes to different employers who were looking for workers. I have also used them on many other occasions, but getting access to one is relatively difficult with out spending money to send copies. Another type of digital component that I interact with is my computer. I use it on a daily basis to type out assignments, e-mail, and to gather information off of the Internet. Also, being a student at Trent University, I have a student card which digitally allows me to take out books, eat, and get in and out of special events all by simply swiping it through a scanner. Digital pocket agendas have become quite common for students. I use one almost every time I use the phone. It contains several phone numbers, important dates, and many reminders that make organization much easier. There are many other digital components that I interact with, but I feel that the ones I have mentioned are the most prevalent in my life.
3.
Just as there are many forms of digital components that I interact with, there are many analog components as well. The most popular analog component that I use is the telephone. Some use fiberoptic lines, but I will refer to the older, more traditional phones. There are many reasons why I use the phone such as keeping in touch with family and friends, calling my boss at work, or ordering a pizza. In today's hi-tech environment, I can even call JoJo to find out what tomorrow will bring. For me, the telephone is the easiest way to get in touch with people. I find that it is much easier to express feelings over the phone for the simple fact that I do not have to be vis-à-vis with the person. Being face to face is sometimes much too personal, and I am far more interested in telling the boss that I cannot come into work without him having to see that I'm not actually sick. Therefore, it is clear that there are many reasons for using a telephone, and that these examples do not only apply to myself, but to many others who use a telephone.
Some feel that because we are in such a hi-tech world, they have to purchase the new high priced advancements. For example, buying a high quality digital watch. I think this to be very unnecessary. I own an old fashioned analog watch. The good old fashioned glow in the dark dial works best for me. I think it's just a status symbol to have the best watch, but then again, I've never seen a 24K gold digital watch. Also, when I am not listening to a CD, I still use cassette tapes. For me there is not much difference in the sound, but I can tell a difference when I want to cue (fast forward or rewind) a song. Obviously, CDs are the 'hip thing' of the 90's, but I find nothing is wrong with a cassette. There are many forms of music that I listen to that are not digital. Many people still have tape players in their vehicles, which goes to show that I am not the only person who still does not mind analog.
4.
When trying to figure out how far apart two phones are from each other, many forms of calculation come into play. It is easy to estimate that your phone is approximately thirty feet from your neighbors, but that is not very accurate, there are ways to measure the exact distance between two phones. When the police send out a signal that bounces off a moving object and then back to their radar gun, a computer program measures how long it took for the signal to come back and thus executes the calculations. A programmer could easily write a loop program that sends a signal to a far away computer (modem) and then wait for the signal to come back. This loop would allow the computer to figure out how long it took for the signal to reach it's destination, and come back, thus telling the person how far apart the two phones are from each other.
By looking at two phone numbers, one can tell by their dimensions how far apart they may be. For example, if two phones were being compared and one of the phone numbers was (519) 498-0872 and the other phone number was 011-356-7951, one might take a wild guess that these numbers are far from each other. Long distance calls, for some reason, seem to sound a little different than close connection calls. When one notices that the person on the other lines voice sounds faded or with static, they can guess that the call is coming from far away. One could get extremely technical and measure the resistance between two phones, but that is difficult for the average person to do. The easiest ways to tell how far apart two phones are is to estimate. People can estimate this by: voice quality, length of phone number, or by running a loop program.
ComputerScience
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<h3>Computer Science</h3>
<pre><![if !supportEmptyParas]> <![endif]><o:p></o:p></pre><pre>Even before the first computer was conceptualized, data had already been</pre><pre>stored on hard copy medium and used with a machine.<span style="mso-spacerun: yes"> </span>As early as 1801, the</pre><pre>punched card was used as a control device for mechanical looms.<span style="mso-spacerun: yes"> </span>One and</pre><pre>one-half centuries later, IBM joined punched cards to computers, encoding</pre><pre>binary information as patterns of small rectangular holes.<span style="mso-spacerun: yes"> </span>Today, punch</pre><pre>cards are rarely used with computers. Instead, they are used for a handful</pre><pre>of train tickets and election ballots.<span style="mso-spacerun: yes"> </span>Although some may find it</pre><pre>surprising, a computer printout is another type of hard copy medium.<span style="mso-spacerun: yes"> </span></pre><pre>Pictures, barcodes, and term papers are modern examples of data storage</pre><pre>that can later be retrieved using optical technology.<span style="mso-spacerun: yes"> </span>Although it</pre><pre>consumes physical space and requires proper care, non-acidic paper</pre><pre>printouts can hold information for centuries.<span style="mso-spacerun: yes"> </span>If long-term storage is not</pre><pre>of prime concern, magnetic medium can retain tremendous amounts of data</pre><pre>and consume less space than a single piece of paper.</pre><pre><![if !supportEmptyParas]> <![endif]><o:p></o:p></pre><pre>The magnetic technology used for computer data storage is the same</pre><pre>technology used in the various forms of magnetic tape from audiocassette</pre><pre>to videocassette recorders.<span style="mso-spacerun: yes"> </span>One of the first computer storage devices was</pre><pre>the magnetic tape drive. Magnetic tape is a sequential data storage</pre><pre>medium. To read data, a tape drive must wind through the spool of tape to</pre><pre>the exact location of the desired information. To write, the tape drive</pre><pre>encodes data sequentially on the tape. Because tape drives cannot randomly</pre><pre>access or write data like disk drives, and are thus much slower, they have</pre><pre>been replaced as the primary storage device with the hard drive.<span style="mso-spacerun: yes"> </span>The hard</pre><pre>drive is composed of thin layers of rigid magnetic platters stacked on top</pre><pre>of one another like records in a jukebox, and the heads that read and</pre><pre>write data to the spinning platters resemble the arm of a record player.<span style="mso-spacerun: yes"> </span></pre><pre>Floppy disks are another common magnetic storage medium.<span style="mso-spacerun: yes"> </span>They offer</pre><pre>relatively small storage capacity when compared to hard drives, but unlike</pre><pre>hard drives, are portable.<span style="mso-spacerun: yes"> </span>Floppy disks are constructed of a flexible</pre><pre>disk covered by a thin layer of iron oxide that stores data in the form of</pre><pre>magnetic dots. A plastic casing protects the disk: soft for the 51/4-inch</pre><pre>disk, and hard for the 31/2-inch disk.<span style="mso-spacerun: yes"> </span>Magnetic storage medium, for all</pre><pre>its advantages, only has a life expectancy of twenty years.</pre><pre><![if !supportEmptyParas]> <![endif]><o:p></o:p></pre><pre>Data can be stored on electronic medium, such as memory chips.<span style="mso-spacerun: yes"> </span>Every</pre><pre>modern personal computer utilizes electronic circuits to hold data and</pre><pre>instructions.<span style="mso-spacerun: yes"> </span>These devices are categorized as RAM (random access memory)</pre><pre>or ROM (read-only memory), and are compact, reliable, and efficient.<span style="mso-spacerun: yes"> </span>RAM</pre><pre>is volatile, and is primarily used for the temporary storage of programs</pre><pre>that are running.<span style="mso-spacerun: yes"> </span>ROM is non-volatile, and usually holds the basic</pre><pre>instruction sets a computer needs to operate.<span style="mso-spacerun: yes"> </span>Electronic medium is</pre><pre>susceptible to static electricity damage and has a limited life</pre><pre>expectancy, but in the modern personal computer, electronic hardware</pre><pre>usually becomes obsolete before it fails.<span style="mso-spacerun: yes"> </span>Optical storage medium, on the</pre><pre>other hand, will last indefinitely.</pre><pre><![if !supportEmptyParas]> <![endif]><o:p></o:p></pre><pre>Optical storage is an increasingly popular method of storing data.<span style="mso-spacerun: yes"> </span></pre><pre>Optical disk drives use lasers to read and write to their medium. When</pre><pre>writing to an optical disk, a laser creates pits on its surface to</pre><pre>represent data. Areas not burned into pits by the laser are called lands.</pre><pre>The laser reads back the data on the optical disk by scanning for pits and</pre><pre>lands. There are three primary optical disk mediums available for storage:</pre><pre>CD-ROM (compact disc read-only memory), WORM (write once read many), and</pre><pre>rewritable optical disks. The CD-ROM is, by far, the most popular form of</pre><pre>optical disk storage; however, CD-ROMs are read-only. At the factory,</pre><pre>lasers are used to create a master CD-ROM, and a mold is made from the</pre><pre>master and used to create copies. WORM drives are used almost exclusively</pre><pre>for archival storage where it is important that the data cannot be changed</pre><pre>or erased after it is written, for example, financial record storage.</pre><pre>Rewritable optical disks are typically used for data backup and archiving</pre><pre>massive amounts of data, such as image databases.</pre><pre><![if !supportEmptyParas]> <![endif]><o:p></o:p></pre><pre>Although there are many manufacturers of the data storage devices used in</pre><pre>the modern personal computer, each fits into one of four technological</pre><pre>classes according to the material and methods it uses to record</pre><pre>information.<span style="mso-spacerun: yes"> </span>Hardcopy medium existed before the invention of the</pre><pre>computer, and magnetic medium is predominantly used today.<span style="mso-spacerun: yes"> </span>Electronic</pre><pre>medium is used by every computer system, and is used to store instructions</pre><pre>or temporarily hold data.<span style="mso-spacerun: yes"> </span>Finally, optical storage medium utilizes lasers</pre><pre>to read and write information to a disk that lasts indefinitely.<span style="mso-spacerun: yes"> </span>Each</pre><pre>type of medium is suitable for certain functions that computer users</pre><pre>require. Although they use differing technologies, they all have equal</pre><pre>importance in the modern personal computer system.</pre></div>
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<h3>Computer Science</h3>
<pre><![if !supportEmptyParas]> <![endif]><o:p></o:p></pre><pre>Even before the first computer was conceptualized, data had already been</pre><pre>stored on hard copy medium and used with a machine.<span style="mso-spacerun: yes"> </span>As early as 1801, the</pre><pre>punched card was used as a control device for mechanical looms.<span style="mso-spacerun: yes"> </span>One and</pre><pre>one-half centuries later, IBM joined punched cards to computers, encoding</pre><pre>binary information as patterns of small rectangular holes.<span style="mso-spacerun: yes"> </span>Today, punch</pre><pre>cards are rarely used with computers. Instead, they are used for a handful</pre><pre>of train tickets and election ballots.<span style="mso-spacerun: yes"> </span>Although some may find it</pre><pre>surprising, a computer printout is another type of hard copy medium.<span style="mso-spacerun: yes"> </span></pre><pre>Pictures, barcodes, and term papers are modern examples of data storage</pre><pre>that can later be retrieved using optical technology.<span style="mso-spacerun: yes"> </span>Although it</pre><pre>consumes physical space and requires proper care, non-acidic paper</pre><pre>printouts can hold information for centuries.<span style="mso-spacerun: yes"> </span>If long-term storage is not</pre><pre>of prime concern, magnetic medium can retain tremendous amounts of data</pre><pre>and consume less space than a single piece of paper.</pre><pre><![if !supportEmptyParas]> <![endif]><o:p></o:p></pre><pre>The magnetic technology used for computer data storage is the same</pre><pre>technology used in the various forms of magnetic tape from audiocassette</pre><pre>to videocassette recorders.<span style="mso-spacerun: yes"> </span>One of the first computer storage devices was</pre><pre>the magnetic tape drive. Magnetic tape is a sequential data storage</pre><pre>medium. To read data, a tape drive must wind through the spool of tape to</pre><pre>the exact location of the desired information. To write, the tape drive</pre><pre>encodes data sequentially on the tape. Because tape drives cannot randomly</pre><pre>access or write data like disk drives, and are thus much slower, they have</pre><pre>been replaced as the primary storage device with the hard drive.<span style="mso-spacerun: yes"> </span>The hard</pre><pre>drive is composed of thin layers of rigid magnetic platters stacked on top</pre><pre>of one another like records in a jukebox, and the heads that read and</pre><pre>write data to the spinning platters resemble the arm of a record player.<span style="mso-spacerun: yes"> </span></pre><pre>Floppy disks are another common magnetic storage medium.<span style="mso-spacerun: yes"> </span>They offer</pre><pre>relatively small storage capacity when compared to hard drives, but unlike</pre><pre>hard drives, are portable.<span style="mso-spacerun: yes"> </span>Floppy disks are constructed of a flexible</pre><pre>disk covered by a thin layer of iron oxide that stores data in the form of</pre><pre>magnetic dots. A plastic casing protects the disk: soft for the 51/4-inch</pre><pre>disk, and hard for the 31/2-inch disk.<span style="mso-spacerun: yes"> </span>Magnetic storage medium, for all</pre><pre>its advantages, only has a life expectancy of twenty years.</pre><pre><![if !supportEmptyParas]> <![endif]><o:p></o:p></pre><pre>Data can be stored on electronic medium, such as memory chips.<span style="mso-spacerun: yes"> </span>Every</pre><pre>modern personal computer utilizes electronic circuits to hold data and</pre><pre>instructions.<span style="mso-spacerun: yes"> </span>These devices are categorized as RAM (random access memory)</pre><pre>or ROM (read-only memory), and are compact, reliable, and efficient.<span style="mso-spacerun: yes"> </span>RAM</pre><pre>is volatile, and is primarily used for the temporary storage of programs</pre><pre>that are running.<span style="mso-spacerun: yes"> </span>ROM is non-volatile, and usually holds the basic</pre><pre>instruction sets a computer needs to operate.<span style="mso-spacerun: yes"> </span>Electronic medium is</pre><pre>susceptible to static electricity damage and has a limited life</pre><pre>expectancy, but in the modern personal computer, electronic hardware</pre><pre>usually becomes obsolete before it fails.<span style="mso-spacerun: yes"> </span>Optical storage medium, on the</pre><pre>other hand, will last indefinitely.</pre><pre><![if !supportEmptyParas]> <![endif]><o:p></o:p></pre><pre>Optical storage is an increasingly popular method of storing data.<span style="mso-spacerun: yes"> </span></pre><pre>Optical disk drives use lasers to read and write to their medium. When</pre><pre>writing to an optical disk, a laser creates pits on its surface to</pre><pre>represent data. Areas not burned into pits by the laser are called lands.</pre><pre>The laser reads back the data on the optical disk by scanning for pits and</pre><pre>lands. There are three primary optical disk mediums available for storage:</pre><pre>CD-ROM (compact disc read-only memory), WORM (write once read many), and</pre><pre>rewritable optical disks. The CD-ROM is, by far, the most popular form of</pre><pre>optical disk storage; however, CD-ROMs are read-only. At the factory,</pre><pre>lasers are used to create a master CD-ROM, and a mold is made from the</pre><pre>master and used to create copies. WORM drives are used almost exclusively</pre><pre>for archival storage where it is important that the data cannot be changed</pre><pre>or erased after it is written, for example, financial record storage.</pre><pre>Rewritable optical disks are typically used for data backup and archiving</pre><pre>massive amounts of data, such as image databases.</pre><pre><![if !supportEmptyParas]> <![endif]><o:p></o:p></pre><pre>Although there are many manufacturers of the data storage devices used in</pre><pre>the modern personal computer, each fits into one of four technological</pre><pre>classes according to the material and methods it uses to record</pre><pre>information.<span style="mso-spacerun: yes"> </span>Hardcopy medium existed before the invention of the</pre><pre>computer, and magnetic medium is predominantly used today.<span style="mso-spacerun: yes"> </span>Electronic</pre><pre>medium is used by every computer system, and is used to store instructions</pre><pre>or temporarily hold data.<span style="mso-spacerun: yes"> </span>Finally, optical storage medium utilizes lasers</pre><pre>to read and write information to a disk that lasts indefinitely.<span style="mso-spacerun: yes"> </span>Each</pre><pre>type of medium is suitable for certain functions that computer users</pre><pre>require. Although they use differing technologies, they all have equal</pre><pre>importance in the modern personal computer system.</pre></div>
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computer virusses
COMPUTER VIRUSES
Kevan
<1>WHAT IS A COMPUTER VIRUS:
The term usually used to define a computer virus is:
' A computer virus is often malicious software which
replicates itself'
[ Podell 1987 for similar definition ]
- COMPUTER VIRUSES ARE BASICALLY PROGRAMS, LIKE A
SPREADSHEET OR A WORD PROCESSOR.
- PROGRAMS WHICH CAN INSERT EXECUTABLE COPIES OF ITSELF INTO
OTHER PROGRAMS.
- PROGRAMS THAT MANIPULATES PROGRAMS, MODIFIES OTHER
PROGRAMS AND REPRODUCE ITSELF IN THE PROCESS.
Comparing Biological viruses & Computer viruses
*************************************************************
* Attack specific * Attack specific *
* body cells * programs (*.COM *.EXE) *
*************************************************************
* Modify the genetic information * Manipulate the program: *
* of a cell other than previous 1* It performs tasks *
*************************************************************
* New viruses grow in the * The infected program produces *
* infected cell itself * virus programs *
*************************************************************
* Infected cells aren't infected * Program are infected only once*
* more than once by the same cell* by most programs*
*************************************************************
* An infected organism may not * The infected program can work *
* exhibit symptoms for a while * without error for a long time *
*************************************************************
* Not all cells with which the * Program can be made immune *
* virus contact are infected * against certain viruses *
*************************************************************
* Viruses can mutate and thus * Virus program can modify *
* cannot be clearly told apart * themselves & possibly escape *
* * detection this way *
*************************************************************
However, " computer virus " is just another name for a class
of programs. They can do anything that another program can.
The only distinguishing characteristic is the program has
ability to reproduce and infect other programs.
<2>WHAT KIND OF PROGRAM ARE CHARACTERIZED AS A VIRUS PROGRAM:
- PROGRAM WHICH HAS CAPABILITY TO EXECUTE THE MODIFICATION
ON A NUMBER OF PROGRAMS.
- CAPABILITY TO RECOGNIZE A MODIFICATION PERFORMED ON A
PROGRAM.(THE ABILITY TO PREVENT FURTHER MODIFICATION OF
THE SAME PROGRAM UPON SUCH RECONDITION.)
- MODIFIED SOFTWARE ASSUME ATTRIBUTES 1 TO 4.
<3>HOW DOES A VIRUS SPREAD:
A computer virus can only be put into your system either by
yourself or someone else. One way in which a virus can be
put into your computer is via a Trojan Horse.
-TROJAN HORSE IS USUALLY CONTAMINATED IN DISKS WHICH ARE
PARTICULARY PIRATED COPIES OF SOFTWARE. IT IS SIMPLY A
DAMAGING PROGRAM DISGUISED AS AN INNOCENT ONE. MANY
VIRUSES MAYBE HIDDEN IN IT, BUT T.H. THEMSELVES DO NOT
HAVE THE ABILITY TO REPLICATE.
Viruses also can be spread through a Wide Area network
(WAN) or a Local Area Network (LAN) by telephone line.
For example down loading a file from a local BBS.
BBS(bulletin board system)-AN Electronic mailbox that user
can access to send or receive massages.
However, there seems to be countless numbers of ways to
become infected. Every-time you down loads a program from
somewhere or borrowed a disk from a friend, you are taking
a risk of getting infected.
<4>DAMAGES AND SIGNS OF INFECTION:
a.> Fill Up your P.C. with Garbage:
As a virus reproduces, it takes up space. This space cannot
be used by the operator. As more copies of the virus are
made, the memory space is lessened.
b.> Mess Up Files:
Computer files have a fixed method of being stored. With
this being the case, it is very easy for a computer virus to
affect the system so some parts of the accessed files cannot
be located.
c.> Mess Up FAT:
FAT(the File Allocation Table) is the method used to contain
the information required about the location of files stored
on a disk. Any allocation to this information can cause
endless trouble.
d.> Mess Up The Boot Sector:
The boot sector is the special information found on a disk.
Changing the boot sector could result in the inability of the
computer to run.
e.> Format a Disk/ Diskette:
A virus can simply format a disk as the operator would with
the format or initialise command.
f.> Reset The Computer:
To reset the computer, the operator or the user only has to
press a few keys. The virus can do this by sending the codes
to the operating system.
g.> Slowing Things Down:
As the name implies, the object of the virus is to slow down
the running line of the program.
h.> Redefine Keys:
The computer has been program to recognize that certain
codes/ signals symbolize a certain keystroke. The virus
could change the definition of these keystrokes.
i.> Lock The Keyboard: redefining all keys into an empty key.
<5>WHAT TO DO AFTER VIRUS ATTACKS:
When signs of a virus attack have been recognized,
the virus has already reproduced itself several times.
Thus, to get rid of the virus, the user has to hack down
and destroy each one of these copies. The easier way is to:
1. Have the original write protected back-up copy of your
operating system on a diskette.
2. Power down the machine.
3. Boot up the system from the original system diskette.
4. Format the hard disk.
5. Restore all back-ups and all executable program.
*If it's not effective, power down and seek for professional help*
<6> TYPE OF VIRUSES:
a.> OVER-WRITING VIRUSES
b.> NON-OVERWRITNG VIRUSES
c.> MEMORY RESENDENT VIRUSES
<7>PRACTICE SAFE HEX:
Viruses are a day to day reality. Different activities
leads to different exposure. To protect oneself from a
virus, several things can be done:
1. Avoid them in the first place.
2. Discovering and getting rid of them.
3. Repairing the damage.
The simple thing that can cut down on exposure rate are to:
avoid pirate software, checking programs that have been down
loaded form the BBS before running them. Make sure that you
have sufficient backups.
<8> ANTIVIRUS PRODUCTS COMPANY:
The pace at which new antiviral products have been pouring
onto the market has accelerated rapidly since the major
infection of 1988. Indeed, by early 1989, there were over 60
proprietary products making varied claims for effectiveness in
preventing or detecting virus attacks.
For: IBM PCs & Compatibles
DISK DEFENDER PC SAFE McAFEE SCAN
DIRECTOR TECHNOLOGIES THE VOICE CONNECTION McAFEE ASSOCIATES
906 University Place 17835 Skypark Circle 4423 Cheeney Street
Evanston, IL 60201 Irvine, CA 92714 Santa Clara, CA 95054
TEL: (408) 727-4559 TEL: (714) 261-2366 TEL: (408) 988-3832
Price: $ 240.00 U.S. Price: $ 45.00 U.S. Price: $ 80.00 U.S.
Class : HARD.2 Class : SOFT.1 Class: SOFT.3
For: Macintosh Plus, SE, & II(Apple)
VIREX
HJC SOFTWARE
P.O. BOX 51816
Durham, NC 27717
TEL: (919) 490-1277
Price: $ 99.95 U.S.
Class : SOFT.3
*Class 1(infection prevention class)*
Most Class 1 products are unable to distinguish between an
acceptable or unacceptable access to an executable program.
For example, a simply DOS COPY command might cause the waring
appear on screen.
*Class 2(infection detection class)*
All Class 2 products are able to distinguish all DOS
commands. Addition to Class 1's prevention fuction, it is able
to protect all COM and EXE files from infection.
*Class 3(Top class)*
Class 3 products are cable of both prevention & detection
fuctions. And they are cable of removing the infection viruses.
<1>. COMPUTER VIRUSES a high-tech disease
WRITTEN BY: RALF BURGER
PUBLISH BY: ABACUS, U.S.A
<2>. DATA THEFT
WRITTEN BY: HUGO CORNWALL
PUBLISH BY: PONTING-GREEN, LONDON
<3>. COMPUTER VIRUSES,WORMS,DATA DIDDLERS,KILLER
-PROGRAMS, AND OTHER THREATS TO YOUR SYSTEM
WRITTEN BY: JOHN McAFEE & COLIN HAYNES
PUBLISH BY: ST.MARTIN'S PRESS, U.S.A
*************************************************
* COMPUTER VIRUSES CRISIS * THE SECRET WORLD *
* WRITTEN BY: PHILP E FITES * OF COMPUTER *
****************************** WRITTEN BY: *
* COMPUTE'S COMPUTER VIRUSES * ALLAN LNNDELL *
* WRITTEN BY: RALPH ROBERTS * *
********************
Kevan
<1>WHAT IS A COMPUTER VIRUS:
The term usually used to define a computer virus is:
' A computer virus is often malicious software which
replicates itself'
[ Podell 1987 for similar definition ]
- COMPUTER VIRUSES ARE BASICALLY PROGRAMS, LIKE A
SPREADSHEET OR A WORD PROCESSOR.
- PROGRAMS WHICH CAN INSERT EXECUTABLE COPIES OF ITSELF INTO
OTHER PROGRAMS.
- PROGRAMS THAT MANIPULATES PROGRAMS, MODIFIES OTHER
PROGRAMS AND REPRODUCE ITSELF IN THE PROCESS.
Comparing Biological viruses & Computer viruses
*************************************************************
* Attack specific * Attack specific *
* body cells * programs (*.COM *.EXE) *
*************************************************************
* Modify the genetic information * Manipulate the program: *
* of a cell other than previous 1* It performs tasks *
*************************************************************
* New viruses grow in the * The infected program produces *
* infected cell itself * virus programs *
*************************************************************
* Infected cells aren't infected * Program are infected only once*
* more than once by the same cell* by most programs*
*************************************************************
* An infected organism may not * The infected program can work *
* exhibit symptoms for a while * without error for a long time *
*************************************************************
* Not all cells with which the * Program can be made immune *
* virus contact are infected * against certain viruses *
*************************************************************
* Viruses can mutate and thus * Virus program can modify *
* cannot be clearly told apart * themselves & possibly escape *
* * detection this way *
*************************************************************
However, " computer virus " is just another name for a class
of programs. They can do anything that another program can.
The only distinguishing characteristic is the program has
ability to reproduce and infect other programs.
<2>WHAT KIND OF PROGRAM ARE CHARACTERIZED AS A VIRUS PROGRAM:
- PROGRAM WHICH HAS CAPABILITY TO EXECUTE THE MODIFICATION
ON A NUMBER OF PROGRAMS.
- CAPABILITY TO RECOGNIZE A MODIFICATION PERFORMED ON A
PROGRAM.(THE ABILITY TO PREVENT FURTHER MODIFICATION OF
THE SAME PROGRAM UPON SUCH RECONDITION.)
- MODIFIED SOFTWARE ASSUME ATTRIBUTES 1 TO 4.
<3>HOW DOES A VIRUS SPREAD:
A computer virus can only be put into your system either by
yourself or someone else. One way in which a virus can be
put into your computer is via a Trojan Horse.
-TROJAN HORSE IS USUALLY CONTAMINATED IN DISKS WHICH ARE
PARTICULARY PIRATED COPIES OF SOFTWARE. IT IS SIMPLY A
DAMAGING PROGRAM DISGUISED AS AN INNOCENT ONE. MANY
VIRUSES MAYBE HIDDEN IN IT, BUT T.H. THEMSELVES DO NOT
HAVE THE ABILITY TO REPLICATE.
Viruses also can be spread through a Wide Area network
(WAN) or a Local Area Network (LAN) by telephone line.
For example down loading a file from a local BBS.
BBS(bulletin board system)-AN Electronic mailbox that user
can access to send or receive massages.
However, there seems to be countless numbers of ways to
become infected. Every-time you down loads a program from
somewhere or borrowed a disk from a friend, you are taking
a risk of getting infected.
<4>DAMAGES AND SIGNS OF INFECTION:
a.> Fill Up your P.C. with Garbage:
As a virus reproduces, it takes up space. This space cannot
be used by the operator. As more copies of the virus are
made, the memory space is lessened.
b.> Mess Up Files:
Computer files have a fixed method of being stored. With
this being the case, it is very easy for a computer virus to
affect the system so some parts of the accessed files cannot
be located.
c.> Mess Up FAT:
FAT(the File Allocation Table) is the method used to contain
the information required about the location of files stored
on a disk. Any allocation to this information can cause
endless trouble.
d.> Mess Up The Boot Sector:
The boot sector is the special information found on a disk.
Changing the boot sector could result in the inability of the
computer to run.
e.> Format a Disk/ Diskette:
A virus can simply format a disk as the operator would with
the format or initialise command.
f.> Reset The Computer:
To reset the computer, the operator or the user only has to
press a few keys. The virus can do this by sending the codes
to the operating system.
g.> Slowing Things Down:
As the name implies, the object of the virus is to slow down
the running line of the program.
h.> Redefine Keys:
The computer has been program to recognize that certain
codes/ signals symbolize a certain keystroke. The virus
could change the definition of these keystrokes.
i.> Lock The Keyboard: redefining all keys into an empty key.
<5>WHAT TO DO AFTER VIRUS ATTACKS:
When signs of a virus attack have been recognized,
the virus has already reproduced itself several times.
Thus, to get rid of the virus, the user has to hack down
and destroy each one of these copies. The easier way is to:
1. Have the original write protected back-up copy of your
operating system on a diskette.
2. Power down the machine.
3. Boot up the system from the original system diskette.
4. Format the hard disk.
5. Restore all back-ups and all executable program.
*If it's not effective, power down and seek for professional help*
<6> TYPE OF VIRUSES:
a.> OVER-WRITING VIRUSES
b.> NON-OVERWRITNG VIRUSES
c.> MEMORY RESENDENT VIRUSES
<7>PRACTICE SAFE HEX:
Viruses are a day to day reality. Different activities
leads to different exposure. To protect oneself from a
virus, several things can be done:
1. Avoid them in the first place.
2. Discovering and getting rid of them.
3. Repairing the damage.
The simple thing that can cut down on exposure rate are to:
avoid pirate software, checking programs that have been down
loaded form the BBS before running them. Make sure that you
have sufficient backups.
<8> ANTIVIRUS PRODUCTS COMPANY:
The pace at which new antiviral products have been pouring
onto the market has accelerated rapidly since the major
infection of 1988. Indeed, by early 1989, there were over 60
proprietary products making varied claims for effectiveness in
preventing or detecting virus attacks.
For: IBM PCs & Compatibles
DISK DEFENDER PC SAFE McAFEE SCAN
DIRECTOR TECHNOLOGIES THE VOICE CONNECTION McAFEE ASSOCIATES
906 University Place 17835 Skypark Circle 4423 Cheeney Street
Evanston, IL 60201 Irvine, CA 92714 Santa Clara, CA 95054
TEL: (408) 727-4559 TEL: (714) 261-2366 TEL: (408) 988-3832
Price: $ 240.00 U.S. Price: $ 45.00 U.S. Price: $ 80.00 U.S.
Class : HARD.2 Class : SOFT.1 Class: SOFT.3
For: Macintosh Plus, SE, & II(Apple)
VIREX
HJC SOFTWARE
P.O. BOX 51816
Durham, NC 27717
TEL: (919) 490-1277
Price: $ 99.95 U.S.
Class : SOFT.3
*Class 1(infection prevention class)*
Most Class 1 products are unable to distinguish between an
acceptable or unacceptable access to an executable program.
For example, a simply DOS COPY command might cause the waring
appear on screen.
*Class 2(infection detection class)*
All Class 2 products are able to distinguish all DOS
commands. Addition to Class 1's prevention fuction, it is able
to protect all COM and EXE files from infection.
*Class 3(Top class)*
Class 3 products are cable of both prevention & detection
fuctions. And they are cable of removing the infection viruses.
<1>. COMPUTER VIRUSES a high-tech disease
WRITTEN BY: RALF BURGER
PUBLISH BY: ABACUS, U.S.A
<2>. DATA THEFT
WRITTEN BY: HUGO CORNWALL
PUBLISH BY: PONTING-GREEN, LONDON
<3>. COMPUTER VIRUSES,WORMS,DATA DIDDLERS,KILLER
-PROGRAMS, AND OTHER THREATS TO YOUR SYSTEM
WRITTEN BY: JOHN McAFEE & COLIN HAYNES
PUBLISH BY: ST.MARTIN'S PRESS, U.S.A
*************************************************
* COMPUTER VIRUSES CRISIS * THE SECRET WORLD *
* WRITTEN BY: PHILP E FITES * OF COMPUTER *
****************************** WRITTEN BY: *
* COMPUTE'S COMPUTER VIRUSES * ALLAN LNNDELL *
* WRITTEN BY: RALPH ROBERTS * *
********************
Computer Viruses
COMPUTER VIRUSES
(anonymous)
<1>WHAT IS A COMPUTER VIRUS:
The term usually used to define a computer virus is:
' A computer virus is often malicious software which
replicates itself'
[ Podell 1987 for similar definition ]
- COMPUTER VIRUSES ARE BASICALLY PROGRAMS, LIKE A
SPREADSHEET OR A WORD PROCESSOR.
- PROGRAMS WHICH CAN INSERT EXECUTABLE COPIES OF ITSELF INTO
OTHER PROGRAMS.
- PROGRAMS THAT MANIPULATES PROGRAMS, MODIFIES OTHER
PROGRAMS AND REPRODUCE ITSELF IN THE PROCESS.
Comparing Biological viruses & Computer viruses
*************************************************************
* Attack specific * Attack specific *
* body cells * programs (*.COM *.EXE) *
*************************************************************
* Modify the genetic information * Manipulate the program: *
* of a cell other than previous 1* It performs tasks *
*************************************************************
* New viruses grow in the * The infected program produces *
* infected cell itself * virus programs *
*************************************************************
* Infected cells aren't infected * Program are infected only once*
* more than once by the same cell* by most programs*
*************************************************************
* An infected organism may not * The infected program can work *
* exhibit symptoms for a while * without error for a long time *
*************************************************************
* Not all cells with which the * Program can be made immune *
* virus contact are infected * against certain viruses *
*************************************************************
* Viruses can mutate and thus * Virus program can modify *
* cannot be clearly told apart * themselves & possibly escape *
* * detection this way *
*************************************************************
However, " computer virus " is just another name for a class
of programs. They can do anything that another program can.
The only distinguishing characteristic is the program has
ability to reproduce and infect other programs.
<2>WHAT KIND OF PROGRAM ARE CHARACTERIZED AS A VIRUS PROGRAM:
- PROGRAM WHICH HAS CAPABILITY TO EXECUTE THE MODIFICATION
ON A NUMBER OF PROGRAMS.
- CAPABILITY TO RECOGNIZE A MODIFICATION PERFORMED ON A
PROGRAM.(THE ABILITY TO PREVENT FURTHER MODIFICATION OF
THE SAME PROGRAM UPON SUCH RECONDITION.)
- MODIFIED SOFTWARE ASSUME ATTRIBUTES 1 TO 4.
<3>HOW DOES A VIRUS SPREAD:
A computer virus can only be put into your system either by
yourself or someone else. One way in which a virus can be
put into your computer is via a Trojan Horse.
-TROJAN HORSE IS USUALLY CONTAMINATED IN DISKS WHICH ARE
PARTICULARY PIRATED COPIES OF SOFTWARE. IT IS SIMPLY A
DAMAGING PROGRAM DISGUISED AS AN INNOCENT ONE. MANY
VIRUSES MAYBE HIDDEN IN IT, BUT T.H. THEMSELVES DO NOT
HAVE THE ABILITY TO REPLICATE.
Viruses also can be spread through a Wide Area network
(WAN) or a Local Area Network (LAN) by telephone line.
For example down loading a file from a local BBS.
BBS(bulletin board system)-AN Electronic mailbox that user
can access to send or receive massages.
However, there seems to be countless numbers of ways to
become infected. Every-time you down loads a program from
somewhere or borrowed a disk from a friend, you are taking
a risk of getting infected.
<4>DAMAGES AND SIGNS OF INFECTION:
a.> Fill Up your P.C. with Garbage:
As a virus reproduces, it takes up space. This space cannot
be used by the operator. As more copies of the virus are
made, the memory space is lessened.
b.> Mess Up Files:
Computer files have a fixed method of being stored. With
this being the case, it is very easy for a computer virus to
affect the system so some parts of the accessed files cannot
be located.
c.> Mess Up FAT:
FAT(the File Allocation Table) is the method used to contain
the information required about the location of files stored
on a disk. Any allocation to this information can cause
endless trouble.
d.> Mess Up The Boot Sector:
The boot sector is the special information found on a disk.
Changing the boot sector could result in the inability of the
computer to run.
e.> Format a Disk/ Diskette:
A virus can simply format a disk as the operator would with
the format or initialise command.
f.> Reset The Computer:
To reset the computer, the operator or the user only has to
press a few keys. The virus can do this by sending the codes
to the operating system.
g.> Slowing Things Down:
As the name implies, the object of the virus is to slow down
the running line of the program.
h.> Redefine Keys:
The computer has been program to recognize that certain
codes/ signals symbolize a certain keystroke. The virus
could change the definition of these keystrokes.
i.> Lock The Keyboard: redefining all keys into an empty key.
<5>WHAT TO DO AFTER VIRUS ATTACKS:
When signs of a virus attack have been recognized,
the virus has already reproduced itself several times.
Thus, to get rid of the virus, the user has to hack down
and destroy each one of these copies. The easier way is to:
1. Have the original write protected back-up copy of your
operating system on a diskette.
2. Power down the machine.
3. Boot up the system from the original system diskette.
4. Format the hard disk.
5. Restore all back-ups and all executable program.
*If it's not effective, power down and seek for professional help*
<6> TYPE OF VIRUSES:
a.> OVER-WRITING VIRUSES
b.> NON-OVERWRITNG VIRUSES
c.> MEMORY RESENDENT VIRUSES
<7>PRACTICE SAFE HEX:
Viruses are a day to day reality. Different activities
leads to different exposure. To protect oneself from a
virus, several things can be done:
1. Avoid them in the first place.
2. Discovering and getting rid of them.
3. Repairing the damage.
The simple thing that can cut down on exposure rate are to:
avoid pirate software, checking programs that have been down
loaded form the BBS before running them. Make sure that you
have sufficient backups.
<8> ANTIVIRUS PRODUCTS COMPANY:
The pace at which new antiviral products have been pouring
onto the market has accelerated rapidly since the major
infection of 1988. Indeed, by early 1989, there were over 60
proprietary products making varied claims for effectiveness in
preventing or detecting virus attacks.
For: IBM PCs & Compatibles
DISK DEFENDER PC SAFE McAFEE SCAN
DIRECTOR TECHNOLOGIES THE VOICE CONNECTION McAFEE ASSOCIATES
906 University Place 17835 Skypark Circle 4423 Cheeney Street
Evanston, IL 60201 Irvine, CA 92714 Santa Clara, CA 95054
TEL: (408) 727-4559 TEL: (714) 261-2366 TEL: (408) 988-3832
Price: $ 240.00 U.S. Price: $ 45.00 U.S. Price: $ 80.00 U.S.
Class : HARD.2 Class : SOFT.1 Class: SOFT.3
For: Macintosh Plus, SE, & II(Apple)
VIREX
HJC SOFTWARE
P.O. BOX 51816
Durham, NC 27717
TEL: (919) 490-1277
Price: $ 99.95 U.S.
Class : SOFT.3
*Class 1(infection prevention class)*
Most Class 1 products are unable to distinguish between an
acceptable or unacceptable access to an executable program.
For example, a simply DOS COPY command might cause the waring
appear on screen.
*Class 2(infection detection class)*
All Class 2 products are able to distinguish all DOS
commands. Addition to Class 1's prevention fuction, it is able
to protect all COM and EXE files from infection.
*Class 3(Top class)*
Class 3 products are cable of both prevention & detection
fuctions. And they are cable of removing the infection viruses.
<1>. COMPUTER VIRUSES a high-tech disease
WRITTEN BY: RALF BURGER
PUBLISH BY: ABACUS, U.S.A
<2>. DATA THEFT
WRITTEN BY: HUGO CORNWALL
PUBLISH BY: PONTING-GREEN, LONDON
<3>. COMPUTER VIRUSES,WORMS,DATA DIDDLERS,KILLER
-PROGRAMS, AND OTHER THREATS TO YOUR SYSTEM
WRITTEN BY: JOHN McAFEE & COLIN HAYNES
PUBLISH BY: ST.MARTIN'S PRESS, U.S.A
*************************************************
* COMPUTER VIRUSES CRISIS * THE SECRET WORLD *
* WRITTEN BY: PHILP E FITES * OF COMPUTER *
****************************** WRITTEN BY: *
* COMPUTE'S COMPUTER VIRUSES * ALLAN LNNDELL *
* WRITTEN BY: RALPH ROBERTS * *
(anonymous)
<1>WHAT IS A COMPUTER VIRUS:
The term usually used to define a computer virus is:
' A computer virus is often malicious software which
replicates itself'
[ Podell 1987 for similar definition ]
- COMPUTER VIRUSES ARE BASICALLY PROGRAMS, LIKE A
SPREADSHEET OR A WORD PROCESSOR.
- PROGRAMS WHICH CAN INSERT EXECUTABLE COPIES OF ITSELF INTO
OTHER PROGRAMS.
- PROGRAMS THAT MANIPULATES PROGRAMS, MODIFIES OTHER
PROGRAMS AND REPRODUCE ITSELF IN THE PROCESS.
Comparing Biological viruses & Computer viruses
*************************************************************
* Attack specific * Attack specific *
* body cells * programs (*.COM *.EXE) *
*************************************************************
* Modify the genetic information * Manipulate the program: *
* of a cell other than previous 1* It performs tasks *
*************************************************************
* New viruses grow in the * The infected program produces *
* infected cell itself * virus programs *
*************************************************************
* Infected cells aren't infected * Program are infected only once*
* more than once by the same cell* by most programs*
*************************************************************
* An infected organism may not * The infected program can work *
* exhibit symptoms for a while * without error for a long time *
*************************************************************
* Not all cells with which the * Program can be made immune *
* virus contact are infected * against certain viruses *
*************************************************************
* Viruses can mutate and thus * Virus program can modify *
* cannot be clearly told apart * themselves & possibly escape *
* * detection this way *
*************************************************************
However, " computer virus " is just another name for a class
of programs. They can do anything that another program can.
The only distinguishing characteristic is the program has
ability to reproduce and infect other programs.
<2>WHAT KIND OF PROGRAM ARE CHARACTERIZED AS A VIRUS PROGRAM:
- PROGRAM WHICH HAS CAPABILITY TO EXECUTE THE MODIFICATION
ON A NUMBER OF PROGRAMS.
- CAPABILITY TO RECOGNIZE A MODIFICATION PERFORMED ON A
PROGRAM.(THE ABILITY TO PREVENT FURTHER MODIFICATION OF
THE SAME PROGRAM UPON SUCH RECONDITION.)
- MODIFIED SOFTWARE ASSUME ATTRIBUTES 1 TO 4.
<3>HOW DOES A VIRUS SPREAD:
A computer virus can only be put into your system either by
yourself or someone else. One way in which a virus can be
put into your computer is via a Trojan Horse.
-TROJAN HORSE IS USUALLY CONTAMINATED IN DISKS WHICH ARE
PARTICULARY PIRATED COPIES OF SOFTWARE. IT IS SIMPLY A
DAMAGING PROGRAM DISGUISED AS AN INNOCENT ONE. MANY
VIRUSES MAYBE HIDDEN IN IT, BUT T.H. THEMSELVES DO NOT
HAVE THE ABILITY TO REPLICATE.
Viruses also can be spread through a Wide Area network
(WAN) or a Local Area Network (LAN) by telephone line.
For example down loading a file from a local BBS.
BBS(bulletin board system)-AN Electronic mailbox that user
can access to send or receive massages.
However, there seems to be countless numbers of ways to
become infected. Every-time you down loads a program from
somewhere or borrowed a disk from a friend, you are taking
a risk of getting infected.
<4>DAMAGES AND SIGNS OF INFECTION:
a.> Fill Up your P.C. with Garbage:
As a virus reproduces, it takes up space. This space cannot
be used by the operator. As more copies of the virus are
made, the memory space is lessened.
b.> Mess Up Files:
Computer files have a fixed method of being stored. With
this being the case, it is very easy for a computer virus to
affect the system so some parts of the accessed files cannot
be located.
c.> Mess Up FAT:
FAT(the File Allocation Table) is the method used to contain
the information required about the location of files stored
on a disk. Any allocation to this information can cause
endless trouble.
d.> Mess Up The Boot Sector:
The boot sector is the special information found on a disk.
Changing the boot sector could result in the inability of the
computer to run.
e.> Format a Disk/ Diskette:
A virus can simply format a disk as the operator would with
the format or initialise command.
f.> Reset The Computer:
To reset the computer, the operator or the user only has to
press a few keys. The virus can do this by sending the codes
to the operating system.
g.> Slowing Things Down:
As the name implies, the object of the virus is to slow down
the running line of the program.
h.> Redefine Keys:
The computer has been program to recognize that certain
codes/ signals symbolize a certain keystroke. The virus
could change the definition of these keystrokes.
i.> Lock The Keyboard: redefining all keys into an empty key.
<5>WHAT TO DO AFTER VIRUS ATTACKS:
When signs of a virus attack have been recognized,
the virus has already reproduced itself several times.
Thus, to get rid of the virus, the user has to hack down
and destroy each one of these copies. The easier way is to:
1. Have the original write protected back-up copy of your
operating system on a diskette.
2. Power down the machine.
3. Boot up the system from the original system diskette.
4. Format the hard disk.
5. Restore all back-ups and all executable program.
*If it's not effective, power down and seek for professional help*
<6> TYPE OF VIRUSES:
a.> OVER-WRITING VIRUSES
b.> NON-OVERWRITNG VIRUSES
c.> MEMORY RESENDENT VIRUSES
<7>PRACTICE SAFE HEX:
Viruses are a day to day reality. Different activities
leads to different exposure. To protect oneself from a
virus, several things can be done:
1. Avoid them in the first place.
2. Discovering and getting rid of them.
3. Repairing the damage.
The simple thing that can cut down on exposure rate are to:
avoid pirate software, checking programs that have been down
loaded form the BBS before running them. Make sure that you
have sufficient backups.
<8> ANTIVIRUS PRODUCTS COMPANY:
The pace at which new antiviral products have been pouring
onto the market has accelerated rapidly since the major
infection of 1988. Indeed, by early 1989, there were over 60
proprietary products making varied claims for effectiveness in
preventing or detecting virus attacks.
For: IBM PCs & Compatibles
DISK DEFENDER PC SAFE McAFEE SCAN
DIRECTOR TECHNOLOGIES THE VOICE CONNECTION McAFEE ASSOCIATES
906 University Place 17835 Skypark Circle 4423 Cheeney Street
Evanston, IL 60201 Irvine, CA 92714 Santa Clara, CA 95054
TEL: (408) 727-4559 TEL: (714) 261-2366 TEL: (408) 988-3832
Price: $ 240.00 U.S. Price: $ 45.00 U.S. Price: $ 80.00 U.S.
Class : HARD.2 Class : SOFT.1 Class: SOFT.3
For: Macintosh Plus, SE, & II(Apple)
VIREX
HJC SOFTWARE
P.O. BOX 51816
Durham, NC 27717
TEL: (919) 490-1277
Price: $ 99.95 U.S.
Class : SOFT.3
*Class 1(infection prevention class)*
Most Class 1 products are unable to distinguish between an
acceptable or unacceptable access to an executable program.
For example, a simply DOS COPY command might cause the waring
appear on screen.
*Class 2(infection detection class)*
All Class 2 products are able to distinguish all DOS
commands. Addition to Class 1's prevention fuction, it is able
to protect all COM and EXE files from infection.
*Class 3(Top class)*
Class 3 products are cable of both prevention & detection
fuctions. And they are cable of removing the infection viruses.
<1>. COMPUTER VIRUSES a high-tech disease
WRITTEN BY: RALF BURGER
PUBLISH BY: ABACUS, U.S.A
<2>. DATA THEFT
WRITTEN BY: HUGO CORNWALL
PUBLISH BY: PONTING-GREEN, LONDON
<3>. COMPUTER VIRUSES,WORMS,DATA DIDDLERS,KILLER
-PROGRAMS, AND OTHER THREATS TO YOUR SYSTEM
WRITTEN BY: JOHN McAFEE & COLIN HAYNES
PUBLISH BY: ST.MARTIN'S PRESS, U.S.A
*************************************************
* COMPUTER VIRUSES CRISIS * THE SECRET WORLD *
* WRITTEN BY: PHILP E FITES * OF COMPUTER *
****************************** WRITTEN BY: *
* COMPUTE'S COMPUTER VIRUSES * ALLAN LNNDELL *
* WRITTEN BY: RALPH ROBERTS * *
Computer Viruses 4
-----------
Viruses
-----------
A virus is a program that copies itself without the knowledge of the computer user. Typically, a virus spreads from one computer to another by adding itself to an existing piece of executable code so that it is executed when its host code is run. If a virus if found, you shouldn't panic or be in a hurry, and you should work systematically. Don't rush!
A Viruse may be classified by it's method of concealment (hiding). Some are called stealth viruses because of the way that they hide themselves, and some polymorphic because of the way they change themselves to avoid scanners from detecting them.
The most common classification relates to the sort of executable code which the virus attaches itself to. These are:
¨ Partition Viruses
¨ Boot Viruses
¨ File Viruses
¨ Overwriting Viruses
As well as replicating, a virus may carry a Damage routine.
There is also a set of programs that are related to viruses by virtue of their intentions, appearances, or users likely reactions. For example:
¨ Droppers
¨ Failed viruses
¨ Packagers
¨ Trojans
¨ Jokes
¨ Test files
THE DAMAGE ROUTINE
Damage is defined as something that you would prefer not to have happened. It is measured by the amount of time it takes to reverse the damage.
Trivial damage happens when all you have to do is get rid of the virus. There may be some audio or visual effect; often there is no effect at all.
Minor damage occurs when you have to replace some or all of your executable files from clean backups, or by re-installing. Remember to run FindVirus again afterwards.
Moderate damage is done when a virus trashes the hard disk, scrambles the FAT, or low-level formats the drive. This is recoverable from your last backup. If you take backups every day you lose, on average, half a day's work.
Major damage is done by a virus that gradually corrupts data files, so that you are unaware of what is happening. When you discover the problem, these corrupted files are also backed up, and you might have to restore a very old backup to get valid data.
Severe damage is done by a virus that gradually corrupts data files, but you cannot see the corruption (there is no simple way of knowing whether the data is good or bad). And, of course, your backups have the same problem.
Unlimited damage is done by a virus that gives a third party access to your network, by stealing the supervisor password. The damage is then done by the third party, who has control of the network.
CLASSIFICATION OF VIRUSES
Stealth Viruses
If a stealth virus is in memory, any program attempting to read the file (or sector) containing the virus is fooled into believing that the virus is not there, as it is hiding. The virus in memory filters out its own bytes, and only shows the original bytes to the program.
There are three ways to deal with this:
1. Cold Boot from a clean DOS floppy, and make sure that nothing on the hard disk is executed. Run any anti-virus software from floppy disk. Unfortunately, although this method is foolproof, relatively few people are willing to do it.
2. Search for known viruses in memory. All the virus scanners do this when the programs are run.
3. Use advanced programming techniques to probe the confusion that the virus causes. A process known as the "Anti-Stealth Methodology" in some scanners can be used for this.
Polymorphic Viruses
A polymorphic virus is one that is encrypted, and the decryptor/loader for the rest of the virus is very variable. With a polymorphic virus, two instances of the virus have no sequence of bytes in common. This makes it more difficult for scanners to detect them.
Many scanners use the "Fuzzy Logic" technique and a "Generic Decryption Engine" to detect these viruses.
The Partition and Partition Viruses
The partition sector is the first sector on a hard disk. It contains information about the disk such as the number of sectors in each partition, where the DOS partition starts, plus a small program. The partition sector is also called the "Master Boot Record" (MBR).
When a PC starts up, it reads the partition sector and executes the code it finds there. Viruses that use the partition sector modify this code.
Since the partition sector is not part of the normal data storage part of a disk, utilities such as DEBUG will not allow access to it. However, it is possible to use Inspect Disk to examine the partition sector. A floppy disk does not have a partition sector.
How to Remove a Partition Sector (MBR) Virus
1. Cold Boot from a clean DOS diskette.
2. Run the DOS scanner.
3. Select the drive to clean and "Repair" it.
4. Follow the instructions.
The Boot Sector and Boot Sector Viruses
The boot sector is the first sector on a floppy disk. On a hard disk it is the first sector of a partition. It contains information about the disk or partition, such as the number of sectors, plus a small program.
When the PC starts up, it attempts to read the boot sector of a disk in drive A:. If this fails because there is no disk, it reads the boot sector of drive C:. A boot sector virus replaces this sector with its own code and moves the original elsewhere on the disk.
Even a non-bootable floppy disk has executable code in its boot sector. This displays the "not bootable" message when the computer attempts to boot from the disk. Therefore, a non-bootable floppy can still contain a virus and infect a PC if it is inserted in drive A: when the PC starts up.
File Viruses
File viruses append or insert themselves into executable files, typically .COM and .EXE programs.
A direct-action file virus infects another executable file on disk when its 'host' executable file is run.
An indirect-action (or TSR - Terminate and Stay Resident) file virus installs itself into memory when its 'host' is executed, and infects other files when they are subsequently accessed.
Overwriting Viruses
Overwriting viruses overwrite all or part of the original program. As a result, the original program doesn't run. Overwriting viruses are not, therefore, a real problem - they are extremely obvious, and so cannot spread effectively.
APPEARANCES AND INTENTIONS OF VIRUSES
Droppers
Droppers are programs that have been written to perform some apparently useful job but, while doing so, write a virus out to the disk. In some cases, all that they do is install the virus (or viruses).
A typical example is a utility that formats a floppy disk, complete with Stoned virus installed on the boot sector.
Failed Viruses
Sometimes a file is found that contains a 'failed virus'. This is the result of either a corrupted 'real' virus or simply a result of bad programming on the part of an aspiring virus writer. The virus does not work - it hangs when run, or fails to infect.
Many viruses have severe bugs that prevent their design goals - some will not reproduce successfully or will fail to perform their intended final actions (such as corrupting the hard disk). In general many virus authors are very poor programmers.
Packagers
Packagers are programs that in some way wrap something around the original program. This could be as an anti-virus precaution, or for file compression. Packagers can mask the existence of a virus inside.
Trojans and Jokes
A Trojan is a program that deliberately does unpleasant things, as well as (or instead of) its declared function. They are not capable of spreading themselves and rely on users copying them.
A Joke is a harmless program that does amusing things, perhaps unexpectedly. We include the detection of a few jokes in the Toolkit, where people have found particular jokes that give concern or offence.
Test files
Test files are used to test and demonstrate anti-virus software, in the context of viruses. They are not viruses - simply small files that are recognised by the software and cause it to simulate what would happen if it had found a virus. This allows users to see what happens when it is triggered, without needing a live virus.
METHODS OF REMOVING VIRUSES
How to Remove a Boot Virus from a Hard Disk
1. Cold Boot from a clean DOS diskette.
2. Run the scanner.
3. Select the drive to clean and "Repair" it.
An alternative method is as follows:
1. Cold Boot from a clean DOS diskette.
2. Type:
SYS C: at the DOS prompt. (if C drive is infected)
The clean DOS diskette should be the same version of DOS that is on the hard disk.
How to Remove a Boot Virus from a Floppy
1. Cold Boot from a clean DOS diskette.
2. Run the scanner.
3. Make sure to "Replace the Boot Sector" of the floppy drive.
If you find a new virus...
If you have some symptoms that you think are a virus, then:
1. Format a floppy disk in the infected computer.
2. Copy any infected files to that floppy.
3. Copy your FORMAT and CHKDSK programs too.
As you can see in this essay, viruses are very appalling, and since a virus spreads from one computer to another, it gets worse! Just like a contagious human virus which causes more harm, as more people are infected and more need to be treated. This same concept applies to a computer virus infecting computers continually. Also, in this essay, various techniques have been explained on how to remove and deal with computer viruses, of different types, inflicting different components in a computer. So, next time you have suspicions that your computer has been damaged by a virus, read through this essay and exercise the remedies indicated.
Viruses
-----------
A virus is a program that copies itself without the knowledge of the computer user. Typically, a virus spreads from one computer to another by adding itself to an existing piece of executable code so that it is executed when its host code is run. If a virus if found, you shouldn't panic or be in a hurry, and you should work systematically. Don't rush!
A Viruse may be classified by it's method of concealment (hiding). Some are called stealth viruses because of the way that they hide themselves, and some polymorphic because of the way they change themselves to avoid scanners from detecting them.
The most common classification relates to the sort of executable code which the virus attaches itself to. These are:
¨ Partition Viruses
¨ Boot Viruses
¨ File Viruses
¨ Overwriting Viruses
As well as replicating, a virus may carry a Damage routine.
There is also a set of programs that are related to viruses by virtue of their intentions, appearances, or users likely reactions. For example:
¨ Droppers
¨ Failed viruses
¨ Packagers
¨ Trojans
¨ Jokes
¨ Test files
THE DAMAGE ROUTINE
Damage is defined as something that you would prefer not to have happened. It is measured by the amount of time it takes to reverse the damage.
Trivial damage happens when all you have to do is get rid of the virus. There may be some audio or visual effect; often there is no effect at all.
Minor damage occurs when you have to replace some or all of your executable files from clean backups, or by re-installing. Remember to run FindVirus again afterwards.
Moderate damage is done when a virus trashes the hard disk, scrambles the FAT, or low-level formats the drive. This is recoverable from your last backup. If you take backups every day you lose, on average, half a day's work.
Major damage is done by a virus that gradually corrupts data files, so that you are unaware of what is happening. When you discover the problem, these corrupted files are also backed up, and you might have to restore a very old backup to get valid data.
Severe damage is done by a virus that gradually corrupts data files, but you cannot see the corruption (there is no simple way of knowing whether the data is good or bad). And, of course, your backups have the same problem.
Unlimited damage is done by a virus that gives a third party access to your network, by stealing the supervisor password. The damage is then done by the third party, who has control of the network.
CLASSIFICATION OF VIRUSES
Stealth Viruses
If a stealth virus is in memory, any program attempting to read the file (or sector) containing the virus is fooled into believing that the virus is not there, as it is hiding. The virus in memory filters out its own bytes, and only shows the original bytes to the program.
There are three ways to deal with this:
1. Cold Boot from a clean DOS floppy, and make sure that nothing on the hard disk is executed. Run any anti-virus software from floppy disk. Unfortunately, although this method is foolproof, relatively few people are willing to do it.
2. Search for known viruses in memory. All the virus scanners do this when the programs are run.
3. Use advanced programming techniques to probe the confusion that the virus causes. A process known as the "Anti-Stealth Methodology" in some scanners can be used for this.
Polymorphic Viruses
A polymorphic virus is one that is encrypted, and the decryptor/loader for the rest of the virus is very variable. With a polymorphic virus, two instances of the virus have no sequence of bytes in common. This makes it more difficult for scanners to detect them.
Many scanners use the "Fuzzy Logic" technique and a "Generic Decryption Engine" to detect these viruses.
The Partition and Partition Viruses
The partition sector is the first sector on a hard disk. It contains information about the disk such as the number of sectors in each partition, where the DOS partition starts, plus a small program. The partition sector is also called the "Master Boot Record" (MBR).
When a PC starts up, it reads the partition sector and executes the code it finds there. Viruses that use the partition sector modify this code.
Since the partition sector is not part of the normal data storage part of a disk, utilities such as DEBUG will not allow access to it. However, it is possible to use Inspect Disk to examine the partition sector. A floppy disk does not have a partition sector.
How to Remove a Partition Sector (MBR) Virus
1. Cold Boot from a clean DOS diskette.
2. Run the DOS scanner.
3. Select the drive to clean and "Repair" it.
4. Follow the instructions.
The Boot Sector and Boot Sector Viruses
The boot sector is the first sector on a floppy disk. On a hard disk it is the first sector of a partition. It contains information about the disk or partition, such as the number of sectors, plus a small program.
When the PC starts up, it attempts to read the boot sector of a disk in drive A:. If this fails because there is no disk, it reads the boot sector of drive C:. A boot sector virus replaces this sector with its own code and moves the original elsewhere on the disk.
Even a non-bootable floppy disk has executable code in its boot sector. This displays the "not bootable" message when the computer attempts to boot from the disk. Therefore, a non-bootable floppy can still contain a virus and infect a PC if it is inserted in drive A: when the PC starts up.
File Viruses
File viruses append or insert themselves into executable files, typically .COM and .EXE programs.
A direct-action file virus infects another executable file on disk when its 'host' executable file is run.
An indirect-action (or TSR - Terminate and Stay Resident) file virus installs itself into memory when its 'host' is executed, and infects other files when they are subsequently accessed.
Overwriting Viruses
Overwriting viruses overwrite all or part of the original program. As a result, the original program doesn't run. Overwriting viruses are not, therefore, a real problem - they are extremely obvious, and so cannot spread effectively.
APPEARANCES AND INTENTIONS OF VIRUSES
Droppers
Droppers are programs that have been written to perform some apparently useful job but, while doing so, write a virus out to the disk. In some cases, all that they do is install the virus (or viruses).
A typical example is a utility that formats a floppy disk, complete with Stoned virus installed on the boot sector.
Failed Viruses
Sometimes a file is found that contains a 'failed virus'. This is the result of either a corrupted 'real' virus or simply a result of bad programming on the part of an aspiring virus writer. The virus does not work - it hangs when run, or fails to infect.
Many viruses have severe bugs that prevent their design goals - some will not reproduce successfully or will fail to perform their intended final actions (such as corrupting the hard disk). In general many virus authors are very poor programmers.
Packagers
Packagers are programs that in some way wrap something around the original program. This could be as an anti-virus precaution, or for file compression. Packagers can mask the existence of a virus inside.
Trojans and Jokes
A Trojan is a program that deliberately does unpleasant things, as well as (or instead of) its declared function. They are not capable of spreading themselves and rely on users copying them.
A Joke is a harmless program that does amusing things, perhaps unexpectedly. We include the detection of a few jokes in the Toolkit, where people have found particular jokes that give concern or offence.
Test files
Test files are used to test and demonstrate anti-virus software, in the context of viruses. They are not viruses - simply small files that are recognised by the software and cause it to simulate what would happen if it had found a virus. This allows users to see what happens when it is triggered, without needing a live virus.
METHODS OF REMOVING VIRUSES
How to Remove a Boot Virus from a Hard Disk
1. Cold Boot from a clean DOS diskette.
2. Run the scanner.
3. Select the drive to clean and "Repair" it.
An alternative method is as follows:
1. Cold Boot from a clean DOS diskette.
2. Type:
SYS C: at the DOS prompt. (if C drive is infected)
The clean DOS diskette should be the same version of DOS that is on the hard disk.
How to Remove a Boot Virus from a Floppy
1. Cold Boot from a clean DOS diskette.
2. Run the scanner.
3. Make sure to "Replace the Boot Sector" of the floppy drive.
If you find a new virus...
If you have some symptoms that you think are a virus, then:
1. Format a floppy disk in the infected computer.
2. Copy any infected files to that floppy.
3. Copy your FORMAT and CHKDSK programs too.
As you can see in this essay, viruses are very appalling, and since a virus spreads from one computer to another, it gets worse! Just like a contagious human virus which causes more harm, as more people are infected and more need to be treated. This same concept applies to a computer virus infecting computers continually. Also, in this essay, various techniques have been explained on how to remove and deal with computer viruses, of different types, inflicting different components in a computer. So, next time you have suspicions that your computer has been damaged by a virus, read through this essay and exercise the remedies indicated.
COMPUTER SECURITY ANALYSIS
===================================
=INTRODUCTION TO DENIAL OF SERVICE=
===================================
Brian --------
Bri000001@aol.com
Last updated: Friday, March 28, 1997 10:19:23 AM 10:19:23
.0. FOREWORD
.A. INTRODUCTION
.A.1. WHAT IS A DENIAL OF SERVICE ATTACK?
.A.2. WHY WOULD SOMEONE CRASH A SYSTEM?
.A.2.1. INTRODUCTION
.A.2.2. SUB-CULTURAL STATUS
.A.2.3. TO GAIN ACCESS
.A.2.4. REVENGE
.A.2.5. POLITICAL REASONS
.A.2.6. ECONOMICAL REASONS
.A.2.7. NASTINESS
.A.3. ARE SOME OPERATING SYSTEMS MORE SECURE?
.B. SOME BASIC TARGETS FOR AN ATTACK
.B.1. SWAP SPACE
.B.2. BANDWIDTH
.B.3. KERNEL TABLES
.B.4. RAM
.B.5. DISKS
.B.6. CACHES
.B.7. INETD
.C. ATTACKING FROM THE OUTSIDE
.C.1. TAKING ADVANTAGE OF FINGER
.C.2. UDP AND SUNOS 4.1.3.
.C.3. FREEZING UP X-WINDOWS
.C.4. MALICIOUS USE OF UDP SERVICES
.C.5. ATTACKING WITH LYNX CLIENTS
.C.6. MALICIOUS USE OF telnet
.C.7. MALICIOUS USE OF telnet UNDER SOLARIS 2.4
.C.8. HOW TO DISABLE ACCOUNTS
.C.9. LINUX AND TCP TIME, DAYTIME
.C.10. HOW TO DISABLE SERVICES
.C.11. PARAGON OS BETA R1.4
.C.12. NOVELLS NETWARE FTP
.C.13. ICMP REDIRECT ATTACKS
.C.14. BROADCAST STORMS
.C.15. EMAIL BOMBING AND SPAMMING
.C.16. TIME AND KERBEROS
.C.17. THE DOT DOT BUG
.C.18. SUNOS KERNEL PANIC
.C.19. HOSTILE APPLETS
.C.20. VIRUS
.C.21. ANONYMOUS FTP ABUSE
.C.22. SYN FLOODING
.C.23. PING FLOODING
.C.24. CRASHING SYSTEMS WITH PING FROM WINDOWS 95 MACHINES
.C.25. MALICIOUS USE OF SUBNET MASK REPLY MESSAGE
.C.26. FLEXlm
.C.27. BOOTING WITH TRIVIAL FTP
.D. ATTACKING FROM THE INSIDE
.D.1. KERNEL PANIC UNDER SOLARIS 2.3
.D.2. CRASHING THE X-SERVER
.D.3. FILLING UP THE HARD DISK
.D.4. MALICIOUS USE OF eval
.D.5. MALICIOUS USE OF fork()
.D.6. CREATING FILES THAT IS HARD TO REMOVE
.D.7. DIRECTORY NAME LOOKUPCACHE
.D.8. CSH ATTACK
.D.9. CREATING FILES IN /tmp
.D.10. USING RESOLV_HOST_CONF
.D.11. SUN 4.X AND BACKGROUND JOBS
.D.12. CRASHING DG/UX WITH ULIMIT
.D.13. NETTUNE AND HP-UX
.D.14. SOLARIS 2.X AND NFS
.D.15. SYSTEM STABILITY COMPROMISE VIA MOUNT_UNION
.D.16. trap_mon CAUSES KERNEL PANIC UNDER SUNOS 4.1.X
.E. DUMPING CORE
.E.1. SHORT COMMENT
.E.2. MALICIOUS USE OF NETSCAPE
.E.3. CORE DUMPED UNDER WUFTPD
.E.4. ld UNDER SOLARIS/X86
.F. HOW DO I PROTECT A SYSTEM AGAINST DENIAL OF SERVICE ATTACKS?
.F.1. BASIC SECURITY PROTECTION
.F.1.1. INTRODUCTION
.F.1.2. PORT SCANNING
.F.1.3. CHECK THE OUTSIDE ATTACKS DESCRIBED IN THIS PAPER
.F.1.4. CHECK THE INSIDE ATTACKS DESCRIBED IN THIS PAPER
.F.1.5. EXTRA SECURITY SYSTEMS
.F.1.6. MONITORING SECURITY
.F.1.7. KEEPING UP TO DATE
.F.1.8. READ SOMETHING BETTER
.F.2. MONITORING PERFORMANCE
.F.2.1. INTRODUCTION
.F.2.2. COMMANDS AND SERVICES
.F.2.3. PROGRAMS
.F.2.4. ACCOUNTING
.G. SUGGESTED READING
.G.1. INFORMATION FOR DEEPER KNOWLEDGE
.G.2. KEEPING UP TO DATE INFORMATION
.G.3. BASIC INFORMATION
.H. COPYRIGHT
.I. DISCLAIMER
.0. FOREWORD
------------
In this paper I have tried to answer the following questions:
- What is a denial of service attack?
- Why would someone crash a system?
- How can someone crash a system.
- How do I protect a system against denial of service attacks?
I also have a section called SUGGESTED READING were you can find
information about good free information that can give you a deeper
understanding about something.
Note that I have a very limited experience with Macintosh, OS/2 and
Windows and most of the material are therefore for Unix use.
You can always find the latest version at the following address:
http://www.student.tdb.uu.se/~t95hhu/secure/denial/DENIAL.TXT
Feel free to send comments, tips and so on to address:
t95hhu@student.tdb.uu.se
.A. INTRODUCTION
~~~~~~~~~~~~~~~~
.A.1. WHAT IS A DENIAL OF SERVICE ATTACK?
-----------------------------------------
Denial of service is about without permission knocking off
services, for example through crashing the whole system. This
kind of attacks are easy to launch and it is hard to protect
a system against them. The basic problem is that Unix
assumes that users on the system or on other systems will be
well behaved.
.A.2. WHY WOULD SOMEONE CRASH A SYSTEM?
---------------------------------------
.A.2.1. INTRODUCTION
--------------------
Why would someone crash a system? I can think of several reasons
that I have presentated more precisely in a section for each reason,
but for short:
.1. Sub-cultural status.
.2. To gain access.
.3. Revenge.
.4. Political reasons.
.5. Economical reasons.
.6. Nastiness.
I think that number one and six are the more common today, but that
number four and five will be the more common ones in the future.
.A.2.2. SUB-CULTURAL STATUS
---------------------------
After all information about syn flooding a bunch of such attacks
were launched around Sweden. The very most of these attacks were
not a part of a IP-spoof attack, it was "only" a denial of service
attack. Why?
I think that hackers attack systems as a sub-cultural pseudo career
and I think that many denial of service attacks, and here in the
example syn flooding, were performed for these reasons. I also think
that many hackers begin their carrer with denial of service attacks.
.A.2.3. TO GAIN ACCESS
----------------------
Sometimes could a denial of service attack be a part of an attack to
gain access at a system. At the moment I can think of these reasons
and specific holes:
.1. Some older X-lock versions could be crashed with a
method from the denial of service family leaving the system
open. Physical access was needed to use the work space after.
.2. Syn flooding could be a part of a IP-spoof attack method.
.3. Some program systems could have holes under the startup,
that could be used to gain root, for example SSH (secure shell).
.4. Under an attack it could be usable to crash other machines
in the network or to deny certain persons the ability to access
the system.
.5. Also could a system being booted sometimes be subverted,
especially rarp-boots. If we know which port the machine listen
to (69 could be a good guess) under the boot we can send false
packets to it and almost totally control the boot.
.A.2.4. REVENGE
---------------
A denial of service attack could be a part of a revenge against a user
or an administrator.
.A.2.5. POLITICAL REASONS
-------------------------
Sooner or later will new or old organizations understand the potential
of destroying computer systems and find tools to do it.
For example imaginate the Bank A loaning company B money to build a
factory threating the environment. The organization C therefor crash A:s
computer system, maybe with help from an employee. The attack could cost
A a great deal of money if the timing is right.
.A.2.6. ECONOMICAL REASONS
--------------------------
Imaginate the small company A moving into a business totally dominated by
company B. A and B customers make the orders by computers and depends
heavily on that the order is done in a specific time (A and B could be
stock trading companies). If A and B can't perform the order the customers
lose money and change company.
As a part of a business strategy A pays a computer expert a sum of money to
get him to crash B:s computer systems a number of times. A year later A
is the dominating company.
.A.2.7. NASTINESS
-----------------
I know a person that found a workstation where the user had forgotten to
logout. He sat down and wrote a program that made a kill -9 -1 at a
random time at least 30 minutes after the login time and placed a call to
the program from the profile file. That is nastiness.
.A.3. ARE SOME OPERATING SYSTEMS MORE SECURE?
---------------------------------------------
This is a hard question to answer and I don't think that it will
give anything to compare different Unix platforms. You can't say that
one Unix is more secure against denial of service, it is all up to the
administrator.
A comparison between Windows 95 and NT on one side and Unix on the
other could however be interesting.
Unix systems are much more complex and have hundreds of built in programs,
services... This always open up many ways to crash the system from
the inside.
In the normal Windows NT and 95 network were is few ways to crash
the system. Although were is methods that always will work.
That gives us that no big different between Microsoft and Unix can
be seen regardning the inside attacks. But there is a couple of
points left:
- Unix have much more tools and programs to discover an
attack and monitoring the users. To watch what another user
is up to under windows is very hard.
- The average Unix administrator probably also have much more
experience than the average Microsoft administrator.
The two last points gives that Unix is more secure against inside
denial of service attacks.
A comparison between Microsoft and Unix regarding outside attacks
are much more difficult. However I would like to say that the average
Microsoft system on the Internet are more secure against outside
attacks, because they normally have much less services.
.B. SOME BASIC TARGETS FOR AN ATTACK
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.B.1. SWAP SPACE
----------------
Most systems have several hundred Mbytes of swap space to
service client requests. The swap space is typical used
for forked child processes which have a short life time.
The swap space will therefore almost never in a normal
cause be used heavily. A denial of service could be based
on a method that tries to fill up the swap space.
.B.2. BANDWIDTH
---------------
If the bandwidth is to high the network will be useless. Most
denial of service attack influence the bandwidth in some way.
.B.3. KERNEL TABLES
-------------------
It is trivial to overflow the kernel tables which will cause
serious problems on the system. Systems with write through
caches and small write buffers is especially sensitive.
Kernel memory allocation is also a target that is sensitive.
The kernel have a kernelmap limit, if the system reach this
limit it can not allocate more kernel memory and must be rebooted.
The kernel memory is not only used for RAM, CPU:s, screens and so
on, it it also used for ordinaries processes. Meaning that any system
can be crashed and with a mean (or in some sense good) algorithm pretty
fast.
For Solaris 2.X it is measured and reported with the sar command
how much kernel memory the system is using, but for SunOS 4.X there
is no such command. Meaning that under SunOS 4.X you don't even can
get a warning. If you do use So
=INTRODUCTION TO DENIAL OF SERVICE=
===================================
Brian --------
Bri000001@aol.com
Last updated: Friday, March 28, 1997 10:19:23 AM 10:19:23
.0. FOREWORD
.A. INTRODUCTION
.A.1. WHAT IS A DENIAL OF SERVICE ATTACK?
.A.2. WHY WOULD SOMEONE CRASH A SYSTEM?
.A.2.1. INTRODUCTION
.A.2.2. SUB-CULTURAL STATUS
.A.2.3. TO GAIN ACCESS
.A.2.4. REVENGE
.A.2.5. POLITICAL REASONS
.A.2.6. ECONOMICAL REASONS
.A.2.7. NASTINESS
.A.3. ARE SOME OPERATING SYSTEMS MORE SECURE?
.B. SOME BASIC TARGETS FOR AN ATTACK
.B.1. SWAP SPACE
.B.2. BANDWIDTH
.B.3. KERNEL TABLES
.B.4. RAM
.B.5. DISKS
.B.6. CACHES
.B.7. INETD
.C. ATTACKING FROM THE OUTSIDE
.C.1. TAKING ADVANTAGE OF FINGER
.C.2. UDP AND SUNOS 4.1.3.
.C.3. FREEZING UP X-WINDOWS
.C.4. MALICIOUS USE OF UDP SERVICES
.C.5. ATTACKING WITH LYNX CLIENTS
.C.6. MALICIOUS USE OF telnet
.C.7. MALICIOUS USE OF telnet UNDER SOLARIS 2.4
.C.8. HOW TO DISABLE ACCOUNTS
.C.9. LINUX AND TCP TIME, DAYTIME
.C.10. HOW TO DISABLE SERVICES
.C.11. PARAGON OS BETA R1.4
.C.12. NOVELLS NETWARE FTP
.C.13. ICMP REDIRECT ATTACKS
.C.14. BROADCAST STORMS
.C.15. EMAIL BOMBING AND SPAMMING
.C.16. TIME AND KERBEROS
.C.17. THE DOT DOT BUG
.C.18. SUNOS KERNEL PANIC
.C.19. HOSTILE APPLETS
.C.20. VIRUS
.C.21. ANONYMOUS FTP ABUSE
.C.22. SYN FLOODING
.C.23. PING FLOODING
.C.24. CRASHING SYSTEMS WITH PING FROM WINDOWS 95 MACHINES
.C.25. MALICIOUS USE OF SUBNET MASK REPLY MESSAGE
.C.26. FLEXlm
.C.27. BOOTING WITH TRIVIAL FTP
.D. ATTACKING FROM THE INSIDE
.D.1. KERNEL PANIC UNDER SOLARIS 2.3
.D.2. CRASHING THE X-SERVER
.D.3. FILLING UP THE HARD DISK
.D.4. MALICIOUS USE OF eval
.D.5. MALICIOUS USE OF fork()
.D.6. CREATING FILES THAT IS HARD TO REMOVE
.D.7. DIRECTORY NAME LOOKUPCACHE
.D.8. CSH ATTACK
.D.9. CREATING FILES IN /tmp
.D.10. USING RESOLV_HOST_CONF
.D.11. SUN 4.X AND BACKGROUND JOBS
.D.12. CRASHING DG/UX WITH ULIMIT
.D.13. NETTUNE AND HP-UX
.D.14. SOLARIS 2.X AND NFS
.D.15. SYSTEM STABILITY COMPROMISE VIA MOUNT_UNION
.D.16. trap_mon CAUSES KERNEL PANIC UNDER SUNOS 4.1.X
.E. DUMPING CORE
.E.1. SHORT COMMENT
.E.2. MALICIOUS USE OF NETSCAPE
.E.3. CORE DUMPED UNDER WUFTPD
.E.4. ld UNDER SOLARIS/X86
.F. HOW DO I PROTECT A SYSTEM AGAINST DENIAL OF SERVICE ATTACKS?
.F.1. BASIC SECURITY PROTECTION
.F.1.1. INTRODUCTION
.F.1.2. PORT SCANNING
.F.1.3. CHECK THE OUTSIDE ATTACKS DESCRIBED IN THIS PAPER
.F.1.4. CHECK THE INSIDE ATTACKS DESCRIBED IN THIS PAPER
.F.1.5. EXTRA SECURITY SYSTEMS
.F.1.6. MONITORING SECURITY
.F.1.7. KEEPING UP TO DATE
.F.1.8. READ SOMETHING BETTER
.F.2. MONITORING PERFORMANCE
.F.2.1. INTRODUCTION
.F.2.2. COMMANDS AND SERVICES
.F.2.3. PROGRAMS
.F.2.4. ACCOUNTING
.G. SUGGESTED READING
.G.1. INFORMATION FOR DEEPER KNOWLEDGE
.G.2. KEEPING UP TO DATE INFORMATION
.G.3. BASIC INFORMATION
.H. COPYRIGHT
.I. DISCLAIMER
.0. FOREWORD
------------
In this paper I have tried to answer the following questions:
- What is a denial of service attack?
- Why would someone crash a system?
- How can someone crash a system.
- How do I protect a system against denial of service attacks?
I also have a section called SUGGESTED READING were you can find
information about good free information that can give you a deeper
understanding about something.
Note that I have a very limited experience with Macintosh, OS/2 and
Windows and most of the material are therefore for Unix use.
You can always find the latest version at the following address:
http://www.student.tdb.uu.se/~t95hhu/secure/denial/DENIAL.TXT
Feel free to send comments, tips and so on to address:
t95hhu@student.tdb.uu.se
.A. INTRODUCTION
~~~~~~~~~~~~~~~~
.A.1. WHAT IS A DENIAL OF SERVICE ATTACK?
-----------------------------------------
Denial of service is about without permission knocking off
services, for example through crashing the whole system. This
kind of attacks are easy to launch and it is hard to protect
a system against them. The basic problem is that Unix
assumes that users on the system or on other systems will be
well behaved.
.A.2. WHY WOULD SOMEONE CRASH A SYSTEM?
---------------------------------------
.A.2.1. INTRODUCTION
--------------------
Why would someone crash a system? I can think of several reasons
that I have presentated more precisely in a section for each reason,
but for short:
.1. Sub-cultural status.
.2. To gain access.
.3. Revenge.
.4. Political reasons.
.5. Economical reasons.
.6. Nastiness.
I think that number one and six are the more common today, but that
number four and five will be the more common ones in the future.
.A.2.2. SUB-CULTURAL STATUS
---------------------------
After all information about syn flooding a bunch of such attacks
were launched around Sweden. The very most of these attacks were
not a part of a IP-spoof attack, it was "only" a denial of service
attack. Why?
I think that hackers attack systems as a sub-cultural pseudo career
and I think that many denial of service attacks, and here in the
example syn flooding, were performed for these reasons. I also think
that many hackers begin their carrer with denial of service attacks.
.A.2.3. TO GAIN ACCESS
----------------------
Sometimes could a denial of service attack be a part of an attack to
gain access at a system. At the moment I can think of these reasons
and specific holes:
.1. Some older X-lock versions could be crashed with a
method from the denial of service family leaving the system
open. Physical access was needed to use the work space after.
.2. Syn flooding could be a part of a IP-spoof attack method.
.3. Some program systems could have holes under the startup,
that could be used to gain root, for example SSH (secure shell).
.4. Under an attack it could be usable to crash other machines
in the network or to deny certain persons the ability to access
the system.
.5. Also could a system being booted sometimes be subverted,
especially rarp-boots. If we know which port the machine listen
to (69 could be a good guess) under the boot we can send false
packets to it and almost totally control the boot.
.A.2.4. REVENGE
---------------
A denial of service attack could be a part of a revenge against a user
or an administrator.
.A.2.5. POLITICAL REASONS
-------------------------
Sooner or later will new or old organizations understand the potential
of destroying computer systems and find tools to do it.
For example imaginate the Bank A loaning company B money to build a
factory threating the environment. The organization C therefor crash A:s
computer system, maybe with help from an employee. The attack could cost
A a great deal of money if the timing is right.
.A.2.6. ECONOMICAL REASONS
--------------------------
Imaginate the small company A moving into a business totally dominated by
company B. A and B customers make the orders by computers and depends
heavily on that the order is done in a specific time (A and B could be
stock trading companies). If A and B can't perform the order the customers
lose money and change company.
As a part of a business strategy A pays a computer expert a sum of money to
get him to crash B:s computer systems a number of times. A year later A
is the dominating company.
.A.2.7. NASTINESS
-----------------
I know a person that found a workstation where the user had forgotten to
logout. He sat down and wrote a program that made a kill -9 -1 at a
random time at least 30 minutes after the login time and placed a call to
the program from the profile file. That is nastiness.
.A.3. ARE SOME OPERATING SYSTEMS MORE SECURE?
---------------------------------------------
This is a hard question to answer and I don't think that it will
give anything to compare different Unix platforms. You can't say that
one Unix is more secure against denial of service, it is all up to the
administrator.
A comparison between Windows 95 and NT on one side and Unix on the
other could however be interesting.
Unix systems are much more complex and have hundreds of built in programs,
services... This always open up many ways to crash the system from
the inside.
In the normal Windows NT and 95 network were is few ways to crash
the system. Although were is methods that always will work.
That gives us that no big different between Microsoft and Unix can
be seen regardning the inside attacks. But there is a couple of
points left:
- Unix have much more tools and programs to discover an
attack and monitoring the users. To watch what another user
is up to under windows is very hard.
- The average Unix administrator probably also have much more
experience than the average Microsoft administrator.
The two last points gives that Unix is more secure against inside
denial of service attacks.
A comparison between Microsoft and Unix regarding outside attacks
are much more difficult. However I would like to say that the average
Microsoft system on the Internet are more secure against outside
attacks, because they normally have much less services.
.B. SOME BASIC TARGETS FOR AN ATTACK
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.B.1. SWAP SPACE
----------------
Most systems have several hundred Mbytes of swap space to
service client requests. The swap space is typical used
for forked child processes which have a short life time.
The swap space will therefore almost never in a normal
cause be used heavily. A denial of service could be based
on a method that tries to fill up the swap space.
.B.2. BANDWIDTH
---------------
If the bandwidth is to high the network will be useless. Most
denial of service attack influence the bandwidth in some way.
.B.3. KERNEL TABLES
-------------------
It is trivial to overflow the kernel tables which will cause
serious problems on the system. Systems with write through
caches and small write buffers is especially sensitive.
Kernel memory allocation is also a target that is sensitive.
The kernel have a kernelmap limit, if the system reach this
limit it can not allocate more kernel memory and must be rebooted.
The kernel memory is not only used for RAM, CPU:s, screens and so
on, it it also used for ordinaries processes. Meaning that any system
can be crashed and with a mean (or in some sense good) algorithm pretty
fast.
For Solaris 2.X it is measured and reported with the sar command
how much kernel memory the system is using, but for SunOS 4.X there
is no such command. Meaning that under SunOS 4.X you don't even can
get a warning. If you do use So
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