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Virus Encyclopedia

Welcome to the Virus Encyclopedia of Panda Security.


Threat LevelModerate threatDamageHighDistributionNot widespread
Common name:Jerusalem.B
Technical name:Jerusalem B Family
Threat level:Low
Alias:Viernes 13
Effects:  It activates on Friday 13th and deletes all the files that are run.

Affected platforms:


Detection updated on:Jan. 1, 1991
Country of origin:ISRAEL

Brief Description 


Jerusalem.B is a resident virus that infects files with an EXESYS and COM extension. This virus is activated when the date on the system clock is Friday 13th and it deletes all files run on the computer.

Jerusalem.B increases the size of infected files. The size of a file increases every time the infected file is run. It can also cause the computer to slow down.

Jerusalem.B does not use any specific means to spread. It can reach computers through the usual means used by viruses: Internet downloads, floppy disks, FTP, etc.

Visible Symptoms 


Jerusalem.B is difficult to identify, as it does not display any messages or warnings that indicate that it has infected a computer.