MUHAMMAD GHAZI AIMAN BIN MOHD AIDI

DEFINITION  A computer virus is a malware program that, when executed, replicates by inserting copies of itself (possibly modified) into othercomputer programs, data files, or the boot sector of the hard drive; when this replication succeeds, the affected areas are then said to be "infected". Viruses often perform some type of harmful activity on infected hosts, such as stealing hard disk space or CPU time, accessing private information, corrupting data, displaying political or humorous messages on the user's screen, spamming their contacts, or logging their keystrokes. However, not all viruses carry a destructive payload or attempt to hide themselves—the defining characteristic of viruses is that they are self- replicating computer programs which install themselves without the user's consent.malwareprogramreplicatescomputer programsfilesboot sectorhard drivehard diskCPUlogging their keystrokes

How do Virus spread?  from removable media  from downloads off the Internet  from attachments

Example of Virus  Trojan Horse  Salami Attack  Data diddling  Logic bomb  Worm attack  Internet time theft  Cyber pornography

Trojan Horse  A Trojan horse, or Trojan, in computing is a generally non-self-replicating type of malware program containing malicious code that, when executed, carries out actions determined by the nature of the Trojan, typically causing loss or theft of data, and possible system harm. The term is derived from the story of the wooden horse used to trick defenders of Troy into taking concealed warriors into their city in ancient Anatolia, because computer Trojans often employ a form of social engineering, presenting themselves as routine, useful, or interesting in order to persuade victims to install them on their computers.  A Trojan often acts as a backdoor, contacting a controller which can then have unauthorized access to the affected computer. While Trojans and backdoors are not easily detectable by themselves, computers may appear to run slower due to heavy processor or network usage.

Type of Trojan Horse Payload Trojan horse payloads are almost always designed to cause harm, but can also be harmless. They are classified based on how they breach and damage systems. The six main types of Trojan horse payloads are:  * Remote Accessing  * Data Destruction  * Downloader  * Server Trojan (Proxy, FTP, IRC, , HTTP/HTTPS, etc.)  * Security software disabler  * Denial-of-service attack (DoS)

Salami Attack  The attack is used for the commission of financial crimes.  The key here is to make alteration so insignigficant that in a single case it would go unnoticed. Eg. A bank employees inserts a program into the bank’s serves That deducts a small amount of money from the account of every customer.

Why Salami attack persist?  Computer computations are notoriously subject to small errors involving rounding and truncation, especially when large number are to be combined with small ones.

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

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