Viruses are malicious software programs that spread from computer to computer by infecting files. There are four main ways viruses spread: through floppy disks, downloading infected files from the internet, opening infected email attachments, and installing infected software. Trojan horses are malicious programs that perform undisclosed and harmful actions without the user's knowledge or consent, such as allowing remote access to the infected computer. Salami attacks involve making small, unnoticeable alterations like deducting small amounts of money from many bank accounts to commit financial crimes without detection. Computer viruses can copy themselves and infect systems without permission, affecting the computer system.

1. From:- Wan Nur Aisyah bt Wan Zahari 4 server virus

2. In computer technology, viruses are malicious software programs, a form of malware. By definition, viruses exist on local disk drives and spread from one computer to another through sharing of "infected" files Definition of virus…..

3. Viruses are spread mainly by these four ways: Using a floppy diskette from a machine that has a virus. Downloading a file from the internet (or bulletin board) that contains a virus. Getting an e-mail attachment that contains a virus. Installing software purchased from a store or mail warehouse. While this is the rarest of the ways, software vendors have been found to ship their software with viruses (unknown to them of course) on the installation diskettes/cd-roms.

4. Example of virus Data diddling Salami attack Internet time theft Logic bomb Virus / worm attack Trojan attack Cyber pornography

5. Trojan Horse is a program that does something undocumented which the programmer intended, but that the user would not approve of if he knew about it According to some people, a virus is a particular case of a Trojan Horse, namely one that is able to spread to other programs A simple example of a trojan horse would be a program named "waterfalls.scr" claiming to be a free waterfall screensaver which, when run, instead would allow access to the user's computer remotely. About trojan horse

6. Types of Trojan horse payloads Trojan horse payloads are almost always designed to do various harmful things, but could be harmless. They are broken down in classification based on how they breach systems and the damage they cause. The nine main types of Trojan horse payloads are: Remote Access Data Destructive Email Sending Downloader Proxy Trojan (disguising others as the infected computer) FTP Trojan (adding or copying data from the infected computer) security software disabler denial-of-service attack (DoS) URL trojan (directing the infected computer to only connect to the internet via an expensive dial-up connection)

7. Definition of salami attack This attack is used for the commission of financial crimes

8. The key here is to make the alteration so insignificant that in a single case it would go completely unnoticed, e.g. a bank employee inserts a program into the bank's servers, that deducts a small amount of money from the account of every customer Why Salami Attacks Persist Computer computations are notoriously subject to small errors involving rounding and truncation, especially when large numbers are to be combined with small ones.

9. Computer virus can affect the computer system. It can copy itself and infect a computer without permission or knowledge of the user. Conclusion

10. http://www.iriscan.com/basic.htm http://biometrics.cse.msu.edu/fingerprint.htnl Reference

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