This general description, first used in the wake of the Nimda outbreak in September 2001, is used to describe those threats that come as a composite ‘bundle’ of malicious programs, using several mechanisms to spread and/or attack their victims. This includes the following.

• Spread via e-mail, the Internet, IRC channels, file-sharing networks, download from compromised web sites, etc.
• The use of application vulnerabiities.
• Making use of Trojans to steal confidential data, download other malicious code, launch a DDoS attack, etc.

In the days when MS-DOS was the primary PC operating system, the term ‘multipartite’ was used to describe viruses that used more than one technique to spread (infecting programs and system sectors).