Multipartite Viruses infect both programs and boot sectors. Worms are virus-like programs that are primarily designed to replicate themselves, but often without infecting other files on the computer. Macro Viruses are transmitted in Microsoft applications that support Macros, such as Word and Excel. Recently, malicious hackers have turned to using this Macro functionality to attack your computer. How Viruses Contaminate and Spread A virus is typically inactive until an infected program is run or the boot record is read.
Disks used in an infected system can then carry the virus to another machine.
Programs downloaded from bulletin boards and web sites can also spread viruses. Data files can even spread viruses, thanks to the invention of the Macro Virus. Boot Infecting Viruses should be of a special concern to users who share computers or floppy disks. Every disk contains a boot sector whether it is a bootable disk or not. Once the boot code on the drive is infected, the virus will be loaded into memory every time the computer starts up.