Friday the 13th
This is one of the oldest viruses around, but it is very rare. In fact, it may even be extinct, apart from copies in the hands of virus researchers. The original virus is 419 bytes long, but several minor variants are known, with slightly different lengths.
Like the Lehigh virus it can be stopped simply by making .COM files read-only. Most other viruses are not bothered by this, however.
Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.
A variant where the destructive part has been disabled and which was distributed for demonstration purposes.
This 613 byte virus contains the text:
ENET N§37 Virus benigno - Por EDGE BAND! Realizado por un alumno del Enet 37 (?) 25/5/92 ..Hmmm.. Te parece usar la computadora un Domingo? Presiona una tecla.