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Virus.DOS.Leprosy is a family of dangerous, encrypted, and overwriting DOS viruses. It was the first discovered in the United States on August 1st, 1990.

There are 141 variants in this family, the smallest infection size is only 81 bytes while that of the largest is 47,857 bytes.

Behavior

The virus overwrites executable files in the user's current directory by overwriting the beginning of their binaries when Leprosy is run, making the executables no longer function properly.

The virus does not check the size of a file to be infected. If the file is smaller than the virus itself, the new size of infected file will become the size of the virus.

If COMMAND.COM has been infected, the system may not be able to recognize it after reset.

Payload

Not every variant may contain a payload. For most of the variants, when an infected program is run on Friday 25th of any month, the virus may activate.

Variants

The complete list of variants in this family:

  • Virus.DOS.Leprosy.81
  • Virus.DOS.Leprosy.146
  • Virus.DOS.Leprosy.321
  • Virus.DOS.Leprosy.350
  • Virus.DOS.Leprosy.370
  • Virus.DOS.Leprosy.377
  • Virus.DOS.Leprosy.554
  • Virus.DOS.Leprosy.555
  • Virus.DOS.Leprosy.562
  • Virus.DOS.Leprosy.585
  • Virus.DOS.Leprosy.595
  • Virus.DOS.Leprosy.600
  • Virus.DOS.Leprosy.615
  • Virus.DOS.Leprosy.625 (plus B)
  • Virus.DOS.Leprosy.647
  • Virus.DOS.Leprosy.666 (26 variants; A to X, Night and Tapeworm)
  • Virus.DOS.Leprosy.736
  • Virus.DOS.Leprosy.797
  • Virus.DOS.Leprosy.800
  • Virus.DOS.Leprosy.808 (A, B, M and N)
  • Virus.DOS.Leprosy.814
  • Virus.DOS.Leprosy.907
  • Virus.DOS.Leprosy.946
  • Virus.DOS.Leprosy.1207
  • Virus.DOS.Leprosy.1580 (The Hell Raiser variant)
  • Virus.DOS.Leprosy.1818
  • Virus.DOS.Leprosy.1992 (A and B)
  • Virus.DOS.Leprosy.5120
  • Virus.DOS.Leprosy.5370 (A and B)
  • Virus.DOS.Leprosy.5600
  • Virus.DOS.Leprosy.47857 (A and B)
  • Virus.DOS.Leprosy.Acid.792
  • Virus.DOS.Leprosy.BadBrains (2 variants)
  • Virus.DOS.Leprosy.BadCommand.281
  • Virus.DOS.Leprosy.Beavis.201
  • Virus.DOS.Leprosy.Busted (3 variants)
  • Virus.DOS.Leprosy.Echo.425 (plus B)
  • Virus.DOS.Leprosy.Error.625 (plus B)
  • Virus.DOS.Leprosy.Flood.999
  • Virus.DOS.Leprosy.H-Greed.666 (A, B, C and J)
  • Virus.DOS.Leprosy.HTTM.651
  • Virus.DOS.Leprosy.Jas.792
  • Virus.DOS.Leprosy.Jobo (2 variants)
  • Virus.DOS.Leprosy.Kansas.648
  • Virus.DOS.Leprosy.Lubec.731
  • Virus.DOS.Leprosy.Merci.308
  • Virus.DOS.Leprosy.Misery.664
  • Virus.DOS.Leprosy.Morrison.870
  • Virus.DOS.Leprosy.Oss.591
  • Virus.DOS.Leprosy.Peace.777 (plus B and C)
  • Virus.DOS.Leprosy.Peppy.2209
  • Virus.DOS.Leprosy.Popov.777
  • Virus.DOS.Leprosy.Riot (7 variants)
  • Virus.DOS.Leprosy.Sandra (6 variants)
  • Virus.DOS.Leprosy.Sandra_II (2 variants)
  • Virus.DOS.Leprosy.Sector (2 variants)
  • Virus.DOS.Leprosy.Seneca (8 variants)
  • Virus.DOS.Leprosy.Skism (3 variants)
  • Virus.DOS.Leprosy.Spam.1396
  • Virus.DOS.Leprosy.Taz (8 variants)
  • Virus.DOS.Leprosy.TheThing (2 variants)
  • Virus.DOS.Leprosy.Ultra.1306
  • Virus.DOS.Leprosy.Vic.1000
  • Virus.DOS.Leprosy.Violator (A and B)
  • Virus.DOS.Leprosy.YH.880

References

  1. Description of the Leprosy virus on Online VSUM
  2. List of variants of the Leprosy virus on VX heaven