Tools
Terminology
Intended
A program that contains bugs, or other problems, which prevent it from functioning as the author intended. It would have been malware, and future versions still might be, but the current version is defective.
Joke
A program with an annoying or funny functionality. It is not destructive.
Keylogger
A program or hardware component that surreptitiously monitors and stores all the strokes typed into a keyboard. Some keylogger programs will also forward the stored information to an external server for easier retrieval by the attacker.
Keylogger programs may be dropped on a system by other malware, or may be manually installed by the attacker; keylogger hardware must be manually installed. Similarly, keylogger programs will allow an attacker to remotely retrieve the stored information, whereas keylogger hardware must be physically retrieved in order to access the information saved on the device.
Macro
A mini-program found in some applications, macros allow users to automate certain functions or instructions.
Most commonly associated with Microsoft Office applications, macros are commonly used to deliver, execute and hide malware, which are thus often referred to as "macro viruses".
Monitor
A program that can monitor and record all computer activities, including each keystroke typed on the keyboard.
Multipartite Virus
A multi-segmented virus that is able to infect multiple target types – for example, both the boot sector and the system files – in such a way that every section of the virus must be removed before the system can be considered clean and free from the possibility of reinfection.
On-Access Scanner
A virus scanner that runs as a real-time, background process while the user performs other tasks, in order to provide constant protection against malware.
On-Demand Scanner
A virus scanner, usually part of of an antivirus program, which the user must start manually in order to scan the system for infection.
Other
A program that contains or introduces a potential security risk, and does not easily fit into any other category.
Packer
A program that compresses, or reduces, the size of a program's code, often by re-coding it to a smaller size. Packers are used to minimize a program's download times and save storage space. Malicious packers are those commonly used to pack malware.
A program which has been compressed by a packer must be decompressed to its original state before it can be executed. This may be a security risk if the packed program happens to be malware. To mitigate this risk, most virus scanners will identify the packer used to compress a file and if the packer is malicious, the file is flagged.
Virus writers commonly use a variety of packing techniques to prevent virus scanners from identifying a malicious file, including using multiple packers to compress the file.