completely different and should not be confused with each other.

The MDEF, WDEF and CDEF viruses have similar names, but they are



tool.

should not become alarmed if you see them with ResEdit or some other

files. MDEF resources are a normal part of the Macintosh system, so you

The MDEF viruses are named after the type of resource they use to infect



known good copy from an original release disk.

used. You should immediately delete the damaged file and replace it with a

message, telling you that the resulting file is damaged and should not be

removes the virus from the application and issues a special error

Disinfectant cannot repair them properly. In this situation, Disinfectant

The MDEF D virus can damage some applications in such a way that



other problems.

The MDEF C strain contains a serious error which can cause crashes and



protection INITs.

The MDEF B and C strains attempt to bypass some of the popular



can be harmful. They do not display any messages or pictures.

The MDEF viruses do not intentionally attempt to do any damage, yet they



released.

Disinfectant recognizes it anyway, just in case it was inadvertently

not believe that the D strain of MDEF was ever released to the public.

run. An application infected by MDEF D beeps every time it is run. We do

document files. Applications can become infected even if they are never

The D strain of MDEF only infects applications, not system files or



system.

applications become infected as soon as they are run on an infected

System file is infected as soon as an infected application is run. Other

Desktop files. The Finder and DA Handler also usually become infected. The

file. They can also infect document files, other system files, and Finder

The A, B, and C strains of MDEF infect both applications and the System



the CDEF virus.

with the district attorney. The same person was responsible for writing

a juvenile, was released into the custody of his parents after consultation

New York State Police resulted in identification of the author. The author,

Prompt action by computer security personnel and investigators of the



and January, 1991, respectively.

“Top Cat” virus. The C and D strains were discovered in October, 1990

strain was discovered in August, 1990 and is also sometimes called the

May, 1990 and is also sometimes called the “Garfield” virus. The MDEF B

discovered in Ithaca, New York. The MDEF A strain was discovered in

There are four known strains of the MDEF virus. All of them were




xThe MDEF Virus