Category: Malware

Type: Virus

Aliases: SysLock


One unusual "feature" of this virus is that it will search the disk for the string "Microsoft" and change it into "MACROSOFT". The virus will not infect programs if the environment contains SYSLOCK=@.


Automatic action

Based on the settings of your F-Secure security product, it will either automatically delete, quarantine or rename the detected program or file, or ask you for a desired action.

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Technical Details


Two minor variants, which will transform the string "Microsoft" into "MACHOSOFT". One is very close to the original SysLock virus, with only one byte different, but the other has been modified somewhat.


Activates in December and plays "Oh, Tannenbaum".


The last variant is 2232 bytes long and known as "Cookie", because it may display the message

I want a COOKIE!