This category is for viruses that add their code to the end of the file.
“ Cysta also known as Comsysexe is a Polish virus from 1993. Behavior When Cysta is executed, it...Cysta
“ Invol, also known as Involuntary was the first virus to infect .sys files on DOS. Files with a...Invol
“ Natas is a polymorphic, stealth, multipartite virus. It was created by Little Loc also known as...Natas
“ Chill also known as Chill Touch is a DOS virus from 1994. It was found "pre-installed" on a...Chill
“ Kaos4 is a direct-action file infecting virus that gained some prominence in the mid 1990's. It...Kaos4
“ Ply is a rare example of a non-encrypted polymorphic virus. It is the first of its kind, and...Ply