Boot Sector Viruses / Boot block Virus / Boot Virus: It is a type of computer virus that infects the first or first few sectors of the hard disk or floppy disk, which allows the activation of virus as the diskette or drive boots. What boot sector virus does ? Boot sector virus infects computer systems by infecting it own code either to the partition table on a hard disk or the boot sector on a floppy disk. When the system boots from the hard disk or diskettes, virus is executed and installs its own code in the system’s memory. The Boot virus can spread to every disk that the system reads through the memory. These viruses are the most common of all other viruses. The examples of boot viruses are Stoned virus, Michelangelo, Disk Killer, Form, Junkie Virus, and Ohio Virus.

Symptoms ? A boot sector virus may cause several problems relating to boot or data retrieval. There are cases when the data disappears from entire partitions or the computer suddenly becomes unstable. The failure to startup or to find the hard drive are the common problems that can be noticed when the virus attacks a system. You may receive an error message on startup saying, “Bad or missing command interpreter. Enter name of command interpreter.” How it spreads ? When the system boots or is attempting to boot, boot sector viruses are spread to computer systems, from an infected floppy disk. Any disk, even if it is non bootable can cause transmit the virus into memory, if it is in the drive while the system is booting up. The virus can also be spread across networks, if you are downloading files or trying to open up an email attachment.