Summary

This Spanish multi-partite virus infects COM and EXE files and the master boot sectors on hard drives.

Rasek stays resident in memory and infects all executed COM and EXE files. It doesn't infect very small files. The virus decreases the amount of free memory by 2 kilobytes.

Additional Details

There are three known variants:

Rasek.1489: - Length: 1489 bytes - Checks if already resident by calling INT 21/CAFE. If result is

  CACA, the virus has been installed.

- Contains text "RaseK v2.1,from LA CORUNA(SPAIN).Mar93"

Rasek.1490: - Lenght: 1490 bytes - Checks if already resident by calling INT 13/DFDF. If result is

  FDFD, the virus has been installed.

- Contains text "RaseK v2.0,from LA CORUNA(SPAIN).Mar93"

Rasek.1492: - Lenght: 1492 bytes - Checks if already resident by calling INT 21/CAFE. If result is

  CACA, the virus has been installed.

- Contains text "¯RaseK(r) v3.1,from La Coruna(SPAIN).Ap93"

[Analysis: Mikko Hypponen, F-Secure]