The document provides information on various types of computer viruses, including how they infect systems and replicate. It discusses topics like file infectors, boot sector viruses, polymorphic viruses, and worms. Examples are given of different viruses and recommendations are provided on how to protect against computer viruses.

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3. Viruses can infect your computer by reading, or even, previewing, email.
There are many ways that you can find out what these email infectors are and
take the steps to prevent an infection.
You can get a virus as easily as reading an email. A site called the “EMAIL
Help Center” can guide you on how to prevent this from happening to you or
those you send mail to.
You can test whether your email system is vulnerable to email viruses and
attacks such as emails containing mail attachments, web page HTML’s, and
many more types of computer processing that be infected with one of many
different types of viruses.
A computer virus is a self-replicating program containing code that explicitly
copies itself and that can "infect" other programs by modifying them or their
environment such that a call to an infected program implies a call to a possibly
evolved copy of the virus.

4. Since the age of technology arose, and the twentieth century of
computers came about, there have always been an attempt from those trying to
be “smarter” then the average computer, (or computer user, for that matter). It
was the very famous Fred Cohen who "wrote the book" on computer viruses.
He was the soul in the development of a theoretical, and mathematical model
of computer virus behavior. He was able to use his logic to test several
hypothesis about computer virus’s. Cohen's very own, and well-known, informal
definition is "a computer virus is a computer program that can infect
other computer programs by modifying them in such a way as to
include a (possibly evolved) copy of itself". This does not mean that a
computer has to undergo actual destruction(such as deleting or corrupting files)
in order to be classified as a "virus" by Cohen’s definition. Many people use
the term "virus" loosely to cover any sort of program that tries to hide its
possible destructive functions andor tries to spread onto as many computers
as possible; leaving us with a long list of possibilities to deal with.

5. *Patricia Hoffman's hypertext VSUM. It covers PC viruses
and it is regarded by many in the anti virus field as being
inaccurate, so it is advised that you not to rely solely on it. It can
be downloaded from most major archive sites.
*A more precise source of information is the Computer Virus
Catalog,published by the Virus Test Center in Hamburg. It
contains highly technical descriptions of computer viruses for
several platforms: DOS,Mac, Amiga, Atari ST and Unix. It is
available by anonymous FTP from atik.uni-hamburg. For the
directory, go to: pub/virus/texts/catalog.
* Another small collection of a good technical descriptions of PC
viruses,called CARObase, is available from atik.uni-hamburg.

6. *There is plenty of information in the monthly Virus
Bulletin, published in the UK. Among other things, it
gives detailed technical information on viruses . Want a –
month subscribtion: only $395.00!!
*Another source of information is the book "Virus
Encyclopedia" which is part of the printed
documentation of Dr. Solomon's AntiVirus ToolKit (a
commercial DOS antivirus program). The WWW site
www.datafellows.fi, has an on-line, cross-reference data
base containing descriptions of about 1500 PC viruses!
* Lastly, a network-accessible source of information for
viruses is provided by IBM AntiVirus, at
:http://www.brs.ibm.com/ibmav.html.

8. An ARMORED virus is one that uses special tricks to
make tracing,disassembling and understanding of its
code more difficult.
EX.A good example is the Whale virus.
ARMORED Virus

9. A CAVITY VIRUS is one which overwrites a part of
the host file that is filled with a constant (usually
nulls), without increasing the length of the file, but
preserving its functionality.
The Lehigh virus was an early example of a cavity
virus.
CAVITY Virus

10. The COMPANION virus is one that, instead of modifying an
existing file,creates a new program which is executed instead of
the intended program.
On exit, the new program executes the original program so that
things appear normal. On PCs this has usually been
accomplished by creating an infected .COM file with the same
name as an existing .EXE file.
Integrity checking anti virus software that only looks for
modifications in existing files will fail to detect such viruses.
COMPANION VIRUS

11. ComputerVirus & Virus-L
To subscribe to Virus-L, send e-mail to
LISTSERV@LEHIGH.EDU saying
"SUBVIRUS-L your-name". For example:
SUB VIRUS-L Jane Doe To be removed from
the Virus-L mailing list, send a message to
LISTSERV@LEHIGH.EDU saying "SIGNOFF
VIRUS-L". To "subscribe" to comp.virus, simply
use your favorite USENET newsreader to read
the group.

12. Comp.Virus & Virus-L
Virus-L and comp.virus are BOTH “discussion forums”
that focus on computer virus issues.
More specifically, Virus-L is an electronic mailing list
and comp.virus is a USENET newsgroup.
Both groups are moderated; and all submissions are
sent to the moderator who decides if a submission
should be distributed to the groups.
Virus-L is distributed in "digest" format (with multiple
e-mail postings in one large digest) and comp.virus is
distributed as individual news postings.However, the
content of the two groups is identical.

13. The first class of the common PC virus consists of the FILE
INFECTORS which attach themselves to ordinary program
files. These usually infect arbitrary COM and/or EXE
programs,though some can infect any program for which
execution or interpretation is requested, such as SYS, OVL,
OBJ, PRG, MNU and BAT files.
File infectors can be either DIRECT-ACTION or RESIDENT.
A direct-action virus selects one or more programs to infect
each time a program infected by it is executed.
A resident virus installs itself somewhere in memory (RAM)
the first time an infected program is executed, and thereafter
infects other programs when they are executed, or when
other conditions are fulfilled.
Direct-action viruses are also sometimes referred to as NON-
RESIDENT.The Vienna virus is an example of a direct-action
virus. Most viruses are resident.
FILE Infectors…for PC’s

14. A POLYMORPHIC virus is one that produces varied but
operational copies of itself. This is so that virus scanners will
not be able to detect all instances of the virus.
One method of evading scan string-driven virus detectors is
self-encryption with a variable key. These viruses
(Cascades) are not "polymorphic", as their decryption code is
always the same.Therefore the decryptor can be used as a
scan string by the simplest scan string-driven virus scanners
(unless another virus uses the identical decryption routine
and the exact identification.)
POLYMORPHIC Virus

15. The STEALTH virus is one that, while "active“ can hide the
changes it has made to files or boot records. This is achieved
by monitoring the system functions used to read files or
sectors from storage media and forging the results of calls to
such functions. Meaning that programs that try to read
infected files or sectors see the original, uninfected form
instead of the actual, infected form.
The virus's modifications may go undetected by anti virus
programs.: VERY TRICKY
In order to do this, the virus must be a resident in memory
when the anti virus program is executed and this may be
detected by antivirus program.
Stealth Viruses

16. A second PC category of viruses is SYSTEM or
BOOT-RECORD INFECTORS:these viruses infect
executable code found in certain system areas on a
disk.
On PCs there are ordinary boot-sector viruses, which
infect only the DOS boot sector, and MBR viruses
which infect the Master Boot Recordon fixed disks and
the DOS boot sector on diskettes. ( Examples include
Brain, Stoned, Empire, Azusa and Michelangelo.)
All common boot sector and MBR viruses are
memory resident. To confuse this classification
somewhat, a few viruses are able to infect BOTH files
and boot sectors (the Tequila virus is one
SYSTEM or BOOT-RECORD
Infectors

17. The TROJAN HORSE Virus
A “TROJAN HORSE” is a program that does
something undocumented that the programmer
intended, but that some users would not
approve of if they knew about it.
It is a virus, as it is one which is able to spread
to other programs(i.e., it turns them into Trojans
too). A virus that does not do any deliberate
damage (other than merely replicating)is not a
Trojan.

18. A TUNNELLING VIRUS is one that finds the original
interrupt handlers in DOS and the BIOS and calls
them directly.
Then, by passing any activity monitoring program,
which may be loaded and have intercepted, it
interrupts the vectors in its attempt to detect viral
activity.
Some anti virus software also uses these “tunnelling”
techniques in an attempt to by pass any unknown or
undetected virus that may be active when it runs.
TUNNELLING Virus

19. Worms
A computer WORM is a self-contained program
(or set of programs), that is able to spread
functional copies of itself or its segments to
other computer systems (usually via network
connections).
Unlike other viruses, worms do not need to
attach themselves to a host program.
There are two types of worms—
1. “host computer worms”
&

20. NETWORK- Computer Worms
Network worms consist of multiple parts, called
"segments.“ They each run on different
machines (and possibly perform different
actions) using the network for several
communication purposes.
Moving a segment from one machine to another
is only one of their purposes. Network worms
that have only one main segment will coordinate
the work of the other segments; which are
sometimes called "octopuses."

21. HOST- Computer Worms
Host computer worms are entirely
contained in the computer they run on
and use network connections only to
copy themselves to other computers.
Host computer worms are the original
terminates after it launches a copy on
to another host (so there is only one
copy of the worm running somewhere
on the network at any given moment).
They are sometimes called"rabbits."

22. TOP 5 Virus’s Reported
0
2
4
6
8
10
12
14
W32/klez/h W32-
Bugbear-A
W32/ElKern-
C
Percent Reported to
Sophos 2003

23. Protect Yourself fromProtect Yourself from
Computer Virus’sComputer Virus’s
• AVIEN & AVI-EWS
• CERT
• STOPzilla
• GFI Mail Security for
Exchange
• Anti Virus eScan 2003
• CIAC
• Cyber notes
• ICSA
• Information Security Magazine
• NIPC (National Infrastructure
Protection Ctr)
• SANS Institute
• Virus Bulletin

24. Brought to you by Guide Picks…

25. #1 ~ PANDA ANTIVIRUS
PLATIINUM v7.0
Panda Antivirus Platinum v7.0 combines anti
virus and firewall protection to provide robust
security with minimal system impact. Optional
script blocking and attachment filtering
combined with daily updates helps ensure
protection against even new and unknown email
threats. Downside: cumbersome custom
configuration for scans.

26. #2 ~NORTON ANTIVIRUS 2003
This latest version of Norton AntiVirus
offers automatic updating combined with
script blocking and outbound worm
detection. It also includes protection
against IM worms and infected
attachments sent via America Online,
Yahoo!, and MSN instant messenger
programs. Downside: cumbersome
custom configuration for scans.

27. #3~ F-PROT FOR WINDOWS
F-Prot for Windows continues to impress
with solid 100% ItW and 96.34% Zoo
detection. The interface is extremely
pleasing - easy enough for novice users to
navigate yet sophisticated enough for the
more advanced. An excellent addition to any
antiviral arenal. Downside: like other Top
Picks, excluding folders is a cumbersome
task. However, erring on the side of
protection is never a bad idea.

28. #4~ MCAFEE VIRUSSCAN
HOME EDITION 7.0
Scoring 100% detection for ItW threats
and 99.84% Zoo (with a mere .01% false
positive rate), VirusScan Home Edition
provides the protection needed in today's
hostile computing environment. Script
Stopper technology stops VBScript and
JScript worms. Hostile Activity Watch
Kernel looks for suspicious activity and
stops mass-mailing worms. Downside:
Some reports of incompatibility with
ZoneAlarm.

29. #5~ NORMAN VIRUS CONTROL
Norman Virus Control offers a highly respectable
100% rate of detection for ItW threats and
91.92% Zoo with only a .02% false positive rate.
With configurable email attachment blocking,
decompression module, and sandboxing, Norman
Virus Control has earned its second top pick
award. The new interface helps better integrate
the various modules. Downside: cumbersome
custom configuration for scans.

30. #6~ PC-CILLIN
With 100% ItW, 94.82% Zoo detection, and only
a .02% false positive rate, Trend Micro's best-of-
breed anti virus protection features an integrated
firewall and extends its scanning to include even
web-based email. PC-cillin also provides mobile
users the extra protection needed to stay virus-
free on the road, including Wi-Fi connection
security and PDA synchronization protection.

31. #7 ~ BIT DEFENDER
PROFESSIONAL v6.5
Softwin's BitDefender Professional provides
filtering of URLs, IP addresses, and ports, as well
as seamless signature updates every 8 hours.
BitDefender's impressive 100% ItW and 94.21%
Zoo detection also protects against viruses
encountered through the use of ICQ, Yahoo!
Messenger, NetMeeting, or MSN Messenger.

32. #8 ~ NOD 32
Nod32 continues to be a personal
favorite. With a tiny footprint, its
presence on the system is barely
perceptible yet it packs quite a bit of
protection. For older systems, Nod32 may
well be the only antivirus solution capable
of offering superb 100% detection and
prevention of ItW threats without
impacting performance. Downside:
inability to exclude folders from scanning.

33. #9 STOPzilla!
BLOCK annoying popup-windows for good and forever with
STOPzilla!STOPzilla maximizes your surfing speed by guarding your
system against annoying unwanted popup windows. With fully
customizable options that allow you to configure STOPzilla to meet
your surfing needs, you will never again be smothered in an endless
sea of pop-ups!
•Acts like a firewall for popup windows, & Monitors your system while
you surf the web and destroys pop-ups before they open.
•Speeds up your surfing by keeping pop ups at bay, & is Configurable
warnings alert you when a site attempts to open a pop-up.
•Automatically add sites to the STOPzilla Black List to prevent all
future popup attempts.
•Fully customizable settings give you the flexibility to 'ALLOW' or
'BLOCK' with the single click of a mouse.
•Audible alerts let you know when STOPzilla has thwarted a
perpetrator

34. 'SARS' computer virus hits India
Breaking News Story : May 8, 2003
NEW DELHI - Computers in India are vulnerable to a mass mailing worm "SARS", also
known as W32/Coronex-A, which attacks address books and attempts to dupe users.
Micro World Technologies Inc, a content security and IT solutions provider, has
cautioned computer users of the mass mailing worm that uses a variety of subject lines,
message bodies and attachment names, including "SARS Virus" and Hong Kong.exe.
"SARS forwards itself to all contacts in address books and attempts to dupe innocent
computer users into opening an attachment offering details on the current SARS
epidemic. The worm is delivered as an e-mail attachment and the e-mail may have a
subject line about the current paranoia about SARS," a statement said.
The SARS worm just goes onto prove that there are still scores of virus writers who use
common fears to spread dangerous viruses throughout the world, Govind Rammurthy,
MD and CEO, Micro World Inc said.
However, the impact of the worm seems to be less destructive, a security analyst said.
Sunil Chandran, CEO, Stellar info, a data security firm in Delhi said, "The worm has
been in operation since April 24 and so far its nature of destruction is not high and not
widespread and there has been no reporting of data loss by customers to us."

35. What do expert’s believe are in store for
the future of Virus’s?
''Iraq will destroy us by computer,'' the experts screamed
by Rob Rosenburg -- 05/01/03
"IRAQ WILL CRIPPLE the U.S. with cyber-attacks," the fear mongers warned. I tell
you, everyone got into the act -- from Congress to the FBI to former CIA officials to
computer security salesmen.
Even a fire-breathing Muslim cleric living the high life in Britain got into the act. Even
a delusional narcissistic hacker living in the slums of Kuala Lumpur got into the act. I
tell you, everyone screamed about the coming cybergeddon.
I mean, c'mon! How much effort does it take to “open a digital can of whoop-ass” on
the United States? From what I hear, even a 14 year old Iraqi nomad can remotely shut
down our national power grid and remotely pollute our vital toilet water supplies.
In August of last year, an ominous m2g press release quoted CEO D.K. Matai: "it
would seem highly likely that the launch of a physical attack on Iraq will see counter-
attacks from disgruntled Arab, Islamic fundamentalist and anti-American groups."
mi2g warned terrorists might launch remote-controlled “SCADA Attacks” along with
those (equally?) scary "chemical, biological, radiological, [and] nuclear" attacks.

36. CONT. In December 2002, IDC chief research officer John Gantz predicted a major cyber
terrorism event would occur in 2003 -- a cybertastrophe "that will disrupt the economy and bring
the Internet to its knees for at least a day or two," according to News.com scribe Ed Frauenheim.
Gantz specifically warned "the [looming] war with Iraq will galvanize hackers."
A New York Times story in mid-January quoted House Armed Services Committee member
Robert E. Andrews (D-NJ), who warned "a cyber attack really fits Saddam Hussein's paradigm
for attacking us." The same New York Times story quoted ex-FBI flunky Michael Vatis (a well-
documented fear-monger) on the cyber-threat Iraq could pose to U.S. interests should war break
out. ""I would suspect [Iraq's computer warfare program is] at a middling stage ... but even a
middling capability can cause serious harm."
FBI's National Internet Infrastructure Protection Center (now known as DHS NIPC) issued a
pre-war advisory to say Iraq or its sympathizers might cripple the U.S. with Spam.
Meanwhile, Japan's version of NIPC -- the Information Technology Security Center within the
Ministry of Economy -- went on "heightened alert" after their prime minister made comments
supporting the U.S.-led coalition against Iraq. The agency soon upgraded its cyber-threat
assessment and sent a written plea ("written"?) to computer security firms to ask them to "watch
for computer virus attacks and unauthorized changes to Web sites."
According to a Kyodo newswire, Japan's version of NIPC wanted to assure the public "[computer
security firms] will be on alert day and night to be able to act immediately on any abnormal
incidents." No doubt.

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www.uri.edu/personal/dbru7007/biblio.html