This is a large family of related viruses. Many of them were reported to be in the wild in France in December 1995 - February 1996. Most of the WereWolf viruses are resident infectors of COM and EXE files.
Disinfection & Removal
WereWolf is a stealth virus, but it will only stealth the change in file sizes. Virus is not encrypted and contains the following text:
WereWolf avoids infecting the following programs:
CLEAN - McAfee CLEAN AVP - Antiviral Toolkit Pro TB - ThunderByte Antivirus QB - QBasic SCAN - McAfee SCAN COMM - Many communication programs NAV - Norton Antivirus V - Anything starting with a 'V' FINDV - S&S Findvirus GUARD - S&S VirusGuard FV - S&S Findvirus CHKDS - DOS CHKDSK F-PR - F-PROT -D - AVP TSR
This polymorphic variant got widespread distribution in April 1996, as it was attached to a shareware game called 'PackMan', which was available in the upload directory of a major shareware ftp server. This variant has been found in the wild in several countries.
Werewolf.1500.B corrupts data randomly and slowsly while it is being written to the hard drive by any other program. Such changes are very difficult to locate and repair afterwards.
Werewolf.1500.B contains this text:
Description Created: Mikko Hypponen, F-Secure