What Does Dropper Mean?
A dropper is a type of malware developed to launch viruses by "dropping" (installing) them. Dropper viruses may go undetected because they are hidden, difficult to pinpoint and relatively uncommon. Droppers are also a relatively new type of virus that many anti-virus programs are not equipped to detect.
Droppers are programs that contain viruses that impede the functioning of targeted computers. They can install themselves onto a disk or a hard drive. They typically do not duplicate themselves as worms do. Instead, droppers launch their payloads while disguising themselves within computer systems and directories. The code of the virus is contained within the dropper. Usually, dropper viruses are Trojans, and the virus installation takes place in the form of a payload, which is the malicious activity of the virus.
This term is also known as a dropper program or a virus dropper.
Techopedia Explains Dropper
Droppers are not associated with any computer files, making it difficult for anti-virus scanners to capture or detect them. Droppers infest themselves within downloads and suspicious email attachments (common when the email recipient does not recognize the email sender) or are bundled in some other clandestine manner. As such, anti-spyware software is considered to be the most effective tool for dropper detection and deletion.
Droppers may not always be evident right away, but they may cause a PC to slow down, or submit a trigger to steal data once it is gathered. Droppers are not common, but as with most computer viruses, they are becoming more sophisticated and harder for anti-malware programs to detect.
While it is not surprising that viruses are quickly evolving to avoid detection, keep in mind that there are many new and updated anti-spyware programs surfacing as well. To maintain virus protection, it is important to regularly install updates of trusted anti-virus software and to research and consider the newest and most effective anti-virus software.