What is a virus? • A virus is a programme that is loaded onto your computer without your knowledge. • Most viruses ‘infect’ other programmes by modifying them to contain copies of themselves.
Problems caused by viruses • Some viruses are harmless to your system and produce annoying messages or sounds at random time. • Others are quite dangerous by modifying the content or structure of the file system on your hard drive.
Boot sector viruses Programme viruses Macro viruses Three main types of virus
Boot sector viruses • Attach themselves to floppy disks and them copy themselves to the boot sector of your hard drive whenever you turn on or reboot your computer. • source – only floppy disk
Programme viruses • Held within executable files that are associated with programs. They infect your computer when the file is executed. • Common file types – EXE, COM, (DLL, SYS, BIN) • Source – they are actually executed on your computer
Macro viruses • These viruses are developed to run in the macros that some programmes use. • Common programmes used – Microsoft’s Word, Excel
Misconceptions • Safe • reading email message • reading web pages • downloading a file • Dangerous • open the attached file in a email • executed a ‘infected’ programme
How to protect your computer • Antivirus software • call signatures or virus definitions • update regularly the data of viruses • scans the files, sectors and memory, then fixes viruses