Malware – The generic term used for all forms of software designed with malicious intent. Viruses, worms, spyware etc. are all forms of malware. The term virus is often used when malware should really be used as it describes all forms of malicious software.
Virus – A computer virus acts very much like a human virus. Human viruses are spread, via thumb drives, floppy discs, network connections etc., to other PCs. Viruses need a host (like a free screensaver program) to spread. By pure definition: a virus has the ability to spread itself, via a host, to other computers.
Worm – A worm is much like a virus. The key difference is worms can spread between PCs without a host (free screensaver program, downloaded game etc.) These programsrely on computer networks and usually damage files and slow down networks in their path.
Trojan horse (Trojan) – A Trojan horse is a seemingly harmless program that looks to provide value. However, just as in Greek mythology, a Trojan horse has a secret agenda and acts as a backdoor to your computer. This backdoor can be accessed by a hacker to compromise your PC. Trojan horses are not self-replicating and spread due to users installing them manually on their PC.
Privacy-invasive software – A formal term used to describe software that invades your privacy. This software comes in different forms including spyware and adware.
Spyware – Spyware tracks a user’s activity by monitoring browsing habits and keyboard activity and can even take screenshots while you use your PC. This information is sent back to the creator or beneficiary of the spyware. Signs of spyware include: modified browser homepages, slow internet, and suspicious looking sites in place of legitimate sites (for example: banking sites.)
Adware – Like spyware, adware is software that may track visited websites and act as a key logger. Adware tracks this information to automatically display downloaded or installed adverts to a user. You may wonder why you are being offered “PC Super Anti Spyware 2011” when using your PC; this is adware at work. AIM, FlashGet, Deamon Tools, and RealPlayer are all examples of adware.
Backdoor – A backdoor is a point of access to a computer that does not require authentication. An unlocked house back door gives access to an otherwise secure home; a computer backdoor allows access to your PC without your knowledge or permission.
Key logger – Key loggers are used to monitor keyboard activity on a PC. These can be software-based (bundled with Trojan horses, adware, and spyware) or hardware-based (between the keyboard cable and the PC, acoustic etc.) Usually this information is retrieved across a local network, the internet, or from the physical device connected to the keyboard.
Firewall – A firewall both permits and blocks access to a network or PC. Firewalls are included with popular security software (e.g. AVG Internet Security and ESET Smart Security) and limit communication between your PC and devices that are not authorized to communicate with you.
Windows Firewall – Comes bundled with Windows XP, Vista, and 7. This is a great solution; however, due to a lack of comprehensive definition updates, Windows Firewall is not completely effective in blocking threats and allowing safe connections.
Antimalware / Antivirus / Antispyware – Software designed to remove or block malware (e.g. AVG Internet Security and ESET Smart Security.)