Summary of Malicious Code Types

For the purposes of clarity, we will classify malicious code into three areas [23]:

• A Virus is a self-replicating code segment which must be attached to a host executable. When the host is executed, the virus code may also execute. If possible, the virus will replicate by attaching a copy of itself to another executable. The virus may include an additional ``payload'' that triggers when specific conditions are met.



• A Trojan horse is malicious code masquerading as a legitimate application. The goal of the code is to have the user believe they are conducting standard operations or running an innocuous application when in fact initiating its ulterior activities. There are many ways this attack manifests with the most frequent being reliance upon user naivety. A Trojan horse is similar to a virus, except a Trojan horse does not replicate.



• A Worm is a self-replicating program. It is self-contained and does not require a host program. The program creates the copy and causes it to execute; no user intervention is required. Worms commonly utilize network services to propagate to other computer systems [19].