Dropper, Trojan-Dropper

A trojan dropper is a type of malware that acts as a carrier, containing within itself another malicious executable. When launched, it “drops” or installs the contained file and executes it.

Historically-speaking, the term “dropper” was used to describe a file whose sole purpose was to introduce a computer virus into the wild and these were sometimes called “zero generation” viruses by antivirus researchers, in much the same way that “patient zero” was used by doctors and epidemiologists when discussing infectious diseases. In the case of a polymorphic computer virus, its dropper might not be encrypted but could consist solely of the decrypted computer virus code.