A mutant macro virus is essentially a new virus with a different fingerprint, making it difficult to detect with existing fingerprints. In addition, macro viruses can also mate when they meet in the same document, creating a third macro virus that has elements of both parent viruses. File Infectors . This type of virus generally infects uninfected programs when they are executed with the virus in memory. Boot Sector Infectors .
All logical drives contain a boot sector.
The boot sector contains specific information relating to the formatting of the disk and the data stored there. It also contains a small program called the boot program that loads operating system files. Boot sector viruses infect the boot program of the hard drive when an infected diskette is left in a floppy drive and the system is rebooted. When the computer reads and executes the boot sector program, the boot sector virus goes into memory and infects the hard drive. Later, when the user boots from the hard drive, the virus again gains control and can then infect each and every diskette used on the computer.