Multipartite virus

A multipartite virus is a computer virus that infects and spreads in multiple ways. The term was coined to describe the first viruses that included DOS executable files and PC BIOS boot sector virus code, where both parts are viral themselves. Prior to the discovery of the first of these, viruses were categorized as either file infectors or boot infectors. Because of the multiple vectors for the spread of infection, these viruses could spread faster than a boot or file infector alone.

Ghostball was the first multipartite virus, discovered by Fridrik Skulason in October 1989.

Multipartite viruses tend to work fast and some of the infections are subtle and are unnoticed. The following symptoms, may indicate an infection from a multipartite virus:

File infectors viruses are made to infect files of on the computer. File infectors spread once the user runs the infected file. The virus copies itself to locations on the computer where it can be executed; usually in RAM. The file infector will continue to infect files while granting the virus access to the infect files.

Similarly, Boot infectors spread during the boot up of a computer. Boot infectors target the critical section on the hard drive or on floppy disks in order to gain access to the computer. This enables the virus to be able to obtain complete control and/or extract any important information from your computer.

Multipartite viruses increase their chances of spreading within the computer by combining features from both the file infector and the boot infector. These viruses have the ability to infect both files and boot sectors. Because of this, the chance of the virus spreading is increased, but the virus also becomes more vulnerable to detection due to the increased number of locations the virus can be found by an antivirus software.

The multipartite viruses are often tricky and hard to eliminate. When all infected files have been cleaned, but the virus remains in the boot sector, files on the system will be infected again. Similarly, if the boot sectors were disinfected, but the files were still infected, then the boot sector will be re-infected. The process will continually be repeated if the virus is not removed completely from the host system.

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