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

There are 141 variants in this family, the smallest infection size is 81 bytes while that of the largest is 47,857 bytes (46.7KB).


The virus overwrites all the executable files in current directory by overwriting the beginning of their binaries, making them 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 it will become the size of the virus.

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


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


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


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

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