Overwriting Virus An overwriting virus copies its code over its host file's data, thus destroying the original program. Disinfection is possible, although files cannot be recovered. It is usually necessary to delete the original file and replace it with a clean copy. Payload Refers to the effects produced by a virus attack. Sometimes refers to a virus associated with a dropper or Trojan horse.
Some polymorphic virus use different encryption schemes and requires different decryption routines.
Thus, the same virus may look completely different on different systems or even within different files. Other polymorphic viruses vary instruction sequences and use false commands in the attempt to thwart anti-virus software. The process by which a virus makes copies of itself in order to carry out subsequent infections. Replication is one of major criteria separating viruses from other computer programs. A resident virus loads into memory and remains inactive until a trigger event.