Types of Malware

Non-virus malware is often categorized based on its primary intention. If it causes pop-up ads it was called adware. If it sends information from your computer to someplace else without your knowledge it was called spyware. A specialized type of spyware that captures your keystrokes is known as a keylogger. If the malware's only purpose is to download other malware to your computer it was called a "downloader". If it redirects your web searches, or changed your web home page or other settings, it is called a hijacker.

Malware is also categorized based on its method of spreading and infecting. If it crept secretly onto your computer, masquerading as something useful, or bundled with other software, it may be called a trojan horse. If it propogated itself over the network via email or other means, it may be called a worm. These types of malware often try to convince you to purchase "rogue" anti-malware solutions or other products that you don't need and are sometimes referred to as "hoistware".

A single malware infection might have several components and intentions. For instance it might be an adware+spyware trojan horse, or a hijacker worm, or some other combination of the possible classifications. When a new malware entity is discovered, all of its possible classifications might not even be apparent.

Sometimes it is simplest to just refer to the way in which the malware is implemented. For instance a malware file might be implemented as an Activex Control, or a BHO (browser helper object), or as a web browser toolbar. This does not mean that all BHO's or Activex controls or toolbars are bad. It simply means that some malware author chose to implement their nasty program in that manner.