Virus Vs Antivirus

BUSINESS COMMUNICATION AND SOFT SKILL PRESENTATION ON

VIRUS & ANTIVIRUS Presented By, NITIN PATIL. Roll No.- 37

Virus

Virus vs. Anti-Virus: The Arms Race

by---------------------Nitin patil

Outline   

Viruses Anti-Viruses Discussion

Viruses 



A virus is “a program that can ‘infect other programs by modifying them to include a possibly evolved copy of itself.” - Fred Cohen Fred Cohen seems to have been the first to define the term virus, but the concept had been discussed earlier and there were some viruses out in the wild before he began his research.

How does a computer virus identical with a biological virus? ------------Just as a biological virus injects its own genetic information into a cell and interferes with the body’s normal operations, a computer virus is a program written to interfere with the proper functioning of a computer. It may damage programs, delete files, reformat hard disks and perform other forms of destructive acts.

Viruses example 

The WM.Nuclear Microsoft Word macro virus infects Word documents during opening, saving, and printing by adding a set of macros to them. On April 5th it attempts to overwrite critical system files, and it occasionally adds the text "STOP ALL FRENCH NUCLEAR TESTING IN THE PACIFIC!" to the current document. (Information from Symantec’s security bulletin.)

Worms are not viruses The VBS.SST@mm “Anna Kournikova” malware is a worm, not a virus, because it e-mails copies of itself but does not infect any other documents. (Information about VBS.SST@mm from Symantec’s security bulletin.)  ---------------------------------------------------------------------------------------------------------------



Over 85% of all the known viruses are for Microsoft platforms (nearly all the self-propagating worms are as well)

Malware terminology 



a web site listing 56 different terms related to viruses and malware, including:  backdoor  boot sector viruses  Encrypted virus  Hoax  Micro virus More statistics from the web-site  A few hundred are for Javascript, Hypercard, Perl, and other scripting languages. Few of these can spread beyond a few machines without active support of the users  150 are for the Atari  31 are native to the Macintosh, and only two of them are known to exist anymore  2 or 3 are viruses native to OS/2



More statistics from the web-site  About 5 are for Linux/Unix/etc, but none have been found in quantity "in the wild", nor would they be likely to spread very far if they were "loose"  None are for BeOS, ErOS, or other small-population systems.



Question: can we reduce the risk of getting a virus infection by not using Microsoft products?

Example virus 

Fred Cohen’s example virus: program virus := { 1234567; subroutine infect-executable := { loop:file = get-random-executable-file; if first-line-of-file = 1234567 then goto loop; prepend virus to file; } subroutine do-damage := { whatever damage is to be done } subroutine trigger-pulled := { return true if some condition holds } main-program := { infect-executable; if trigger-pulled then do-damage; goto next;} next: }

More about viruses 



Viruses aren’t necessarily hard to write  Cohen reports that his first virus took only 8 hours for an experienced programmer to write. Viruses aren’t necessarily big  Cohen reports on a UNIX shell script virus that was only 7 lines long 

Viruses aren’t necessarily malware- Cohen describes a hypothetical virus that compresses executables to conserve disk space.



Viruses can be malicious in many ways-



Virus action or infection:  Carry bad service attack  Crash the machine  Randomly destroy data  Install a Trojan horse program  Perform password cracking  … and basically any other nasty thing you can not think of.

Isolation 



 





One way to protect against infection is to isolate systems, users, and/or information to make it difficult or impossible for a virus to spread widely. Total isolation is a sure cure.  Total isolation probably isn't practical for most users… Partitioning (controlling or preventing) If we can’t isolate systems and users from each other completely, maybe we can erect partitions to limit the spread of malware. It was thought that the Bell-LaPadula model might help limit the spread of viruses, but Cohen reports that “viruses demonstrated the ability to cross users boundaries and move from a given security level to a higher security level.” Detection-If we can’t limit the spread of a virus, maybe we can find it and quarantine infected files…  Unfortunately, no general algorithm for detecting virus behavior is possible.  Cohen argues this by proposing a virus that infects only when the detection algorithm thinks it isn’t a virus.  Anti-virus programs must make do with more limited solutions, such as scanning for a virus signature.

Virus detection problems 

According to Cohen, the following are undecidable:         

Detection of a virus by its appearance Detection of a virus by its behavior Detection of an evolution of a known virus Detection of a triggering mechanism by its appearance Detection of a triggering mechanism by its behavior Detection of an evolution of a known triggering mechanism Detection of a virus detector by its appearance Detection of a virus detector by its behavior Detection of an evolution of a known viral detector

Known clean system 

Some virus detection techniques require you to start from a clean system.  DOS users used clean boot disks to defeat stealth viruses…  But is it always possible to get to a known clean state?  What if every UNIX vendor had been infected with Ken Thompson’s C compiler virus? Even their “clean” distribution media would be infected… 

‘Now for some good news

“This arms race is usually in favor of the de-obfuscator. The obfuscator has to devise techniques that transform the program without seriously impacting the run-time performance or increasing the binary's size or memory footprint while there are no such constraints for the de-obfuscator.” - Kruegel et al

Que???????????stion 

is it possible that there are viruses in the wild today that have infected large numbers of systems but have gone unnoticed because they have few if any side effects and have not yet triggered their destructive payloads?



Discussion-

Anti-virus can win in the



future?

Thanks You……………………………………