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13/01/1989 Computers across Britain hit by Jerusalem virus

5:42

In Action... Jerusalem Virus

5:07

Virus.DOS.Jerusalem (Friday the 13th Special)

The virus infected EXE files each time they were loaded and caused them to grow in size until they were too large to load into memory. On Friday the 13th, all years but 1987, the virus deleted every program file that was executed. It also changed the well-known message “Bad command or file name” to “Bad Command or file name” which was an easy way to detect it.