03-10-2012, 03:28 PM
SEMINAR ON COMPUTER VIRUS
COMPUTER VIRUS.ppt (Size: 586 KB / Downloads: 62)
INTRODUCTION
A computer virus is one of thousands of programs that can invade computer systems and perform a variety of functions ranging from annoying to dangerous (e.g., deleting files or destroying your hard disk). Trojan horses or worms are specific types of clandestine programs and can be just as dangerous.
Computer viruses are programs that must be triggered or somehow executed before they can infect your computer system and spread to others.
Examples include opening a document infected with a “macro virus,” booting with a diskette infected with a “boot sector” virus, or double-clicking on an infected program file.
Viruses can then be spread by sharing infected files on a diskette, network drive, or other media, by exchanging infected files over the Internet via e-mail attachments, or by downloading questionable files from the Internet.
Definition of Virus
In 1983, Fred Cohen was the first person formally defines a computer virus as 'a computer program that can affect other computer programs by modifying them in such a way as to include a copy of itself
BIGGEST VIRUS EVER?
"Conficker" or "Downadup," this new computer worm has infected more than 9 million computers and is spreading at the rate of 1 million a day, according to the software protection firm, F-Secure. "This is enormous; possibly the biggest virus we have ever seen”.
Symptoms of Virus Attack
Computer runs slower then usual
Computer no longer boots up
Screen sometimes flicker
PC speaker beeps periodically
System crashes for no reason
Files/directories sometimes disappear
Denial of Service (DoS)
How viruses get into computers
File – A virus type that infects existing files on the computer (~40%)
Macro – A virus that runs as a macro in a host application such as the MS Office applications (~35%)
VBScript – A virus that uses Windows Visual Basic Script functionality (~10%)
Internet Worm – A virus that is primarily characterized by it’s replication across the Internet (~5%)
How does anti-virus software work?
Examining files to look for known viruses by means of a virus dictionary
Identifying suspicious behavior from any computer program which might indicate infection
Basic virus defense
Don’t open files that you are not expecting
Many viruses automatically send files without the e-mail account owner’s knowledge.
Ask the sender to confirm unexpected files.
Suspect messages that appear more than once in your Inbox
You may receive the same e-mail from a virus repeatedly.