MDEF was a computer virus affecting Macintosh machines. There are four known strains. The first, MDEF A (aka Garfield), was discovered in May 1990. Strains B (aka Top Cat), C, and D were discovered in August 1990, October 1990, and January 1991, respectively.

MDEF
Technical nameMDEF
AliasGarfield
Top Cat
TypeMacintosh
SubtypeNuisance
ClassificationVirus
FamilyUnknown
OriginIthaca, New York
AuthorsSame author as CDEF

MDEF A, B, and C can infect application files and system files, and sometimes document files as well. The D strain will infect only applications. None of the viruses were designed to do damage, but they often do. MDEF D can sometimes damage applications beyond repair.

Quick action by computer security personnel and the New York State Police resulted in identification of the author, a juvenile. This was the same person responsible for writing the CDEF virus.

References

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  • Norstad, John. The Viruses. Disinfectant 3.7.1 ©1988-1997 Northwestern University.