This category is for viruses that add their code to the end of the file.
“Ply is a rare example of a non-encrypted polymorphic virus. It is the first of its kind, and...Ply
“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
“Cysta also known as Comsysexe is a Polish virus from 1993. When Cysta is executed, it installs...Cysta
“Chill also known as Chill Touch is a DOS virus from 1994. It was found "pre-installed" on a...Chill