Threat description




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

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

More scanning & removal options

More information on the scanning and removal options available in your F-Secure product can be found in the Help Center.

You may also refer to the Knowledge Base on the F-Secure Community site for more information.

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F-Secure customers can request support online via the Request support or the Chat forms on our Home - Global site.

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!

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