Computer Viruses by David Fraser Macro Virus • Macro viruses spread from applications using macros. Worm Virus • A worm is a program that usually spreads over network connections. The worm virus always needs a host program to spread. Polymorphism • These viruses were first introduced in the early 90s and the first one was known as the Chameleon. They are Stealth Viruses. Trojan Horse Virus • The Trojan Horse virus is usually masked to look like something interesting. • Trojan Horse virus steals passwords and sends an E-mail to the hacker’s fake name. Types of Computer Viruses • Stealth Viruses: These viruses actively hide themselves from anti virus programs. • Fast and Slow Infectors: Fast and Slow infect a computer in a particular way. • Armored Viruses: These are programmed to make eradication more difficult. • Multipartite Viruses: Viruses that fall into more then one category. Types of Computer Viruses 2 • Tunneling Viruses: These Viruses tunnel through anti virus programs. • Camouflage Virus: These viruses attempt to appear as a benign program. • Virus Droppers: These place viruses on a computer but are not by themselves an actual virus. Symptoms of a Computer Virus • Computer Programs can no longer load • The Computer’s Hard Drive constantly running out of free space • The floppy disk or hard drives when get active not being used • New files appear on the system with knowing where they came from • Strange sounds from computer or keyboard Symptoms of Computer Virus 2 • Stranger graphics on monitor • Programs keep changing size • Computer is less productive then should be • Programs act erratically • Anything odd happening on a computer can be blamed on a computer virus Ways to Catch a Computer Virus • From Floppy Disks: It can happen if your floppy disk has been in another computer • From the Internet: Viruses can be attached to many files graphics and program files downloaded from the Internet. Ways to Catch Computer Virus 2 • From E-mail: Viruses can be attached to E-mail. • From a Computer Network: They attached to a large computer network called a server. If one is infected by a virus then it won’t be long before everything else is infected. Virus Sources • Computer Viruses do not just appear. • It is known that most virus creators are young men in university, computer store managers. How Viruses Activate • Usually viruses do something harmful to computers when they activate. • When viruses activate they do many different things. • Viruses can harm the programs. How Viruses Spread Out • Usually Computer Viruses join the host program in some way and even write part of it. • Viruses usually spread from files while a multipart virus infects both files and boot sectors. How to provide against Computer Viruses • The best way to protect yourself is to use updated anti virus programs. • When you get an E-mail attachment you should first check the file by checking the attachment with an anti virus program. Viruses in platforms • You cannot just make a computer virus. • Some are designed for different platforms like PC, Macintosh, HP calculators and old computers like Unix. Quiz • 1.Which two Viruses are used as Stealth Viruses? • 2.Name two types of computer viruses. • 3. Give one reason why people created computer viruses. • 4. The _______ virus can steal your account and deliver to the hacker. • 5. Name three ways to counter computer viruses.