This is one of the oldest and most common forms of malware. A computer virus modifies files on a computer in such a way that when a legitimate file is executed, the virus is also executed. Viruses are hard to clean up because they are executed from legitimate programs. To help prevent viruses attacking your computer it is essential that you have a recognised anti-virus program running on your computer and that it is updated regularly.
|Worms||The main difference between a virus and a worm is that the worm has the ability to self-replicate. Unlike computer viruses a worm can spread to other systems and networks without end-user action. Having an up-to-date anti-virus application will help protect your computer from worms.|
|Ransomware||These are malware programs that encrypt your data and hold it for ransom. Over the last few years this type of malware has become very common and sophisticated. Social engineering techniques are used to trick victims into downloading the ransomware. The best defense against ransomware attacks is to backup your files regularly. Under no circumstances should you pay a ransom if your computer is affected as there is no guarantee you will get your data released.|
|Fileless malware||Traditional malware travels and infects new systems using files on the compromised computer. Fileless malware doesn’t directly use files or the file system. Instead it resides in the computer’s memory and is spread from there. As this malware resides in memory it makes it more difficult for anti-virus applications to detect it.|
|Trojans||Trojans masquerade as legitimate programs, but they contain malicious code. A Trojan is generally executed by some action initiated by the victim. Trojans can be delivered as attachments in email on by users visiting sites that contain malicious software. Having an up-to-date anti-virus application will help protect your computer from Trojans. Caution should also be taken when visiting unfamiliar websites.|
|Adware/Spyware||Adware attempts deliver unwanted and potentially malicious advertising to the victim. A common form of adware is to change the default browser page to one that contains advertising. This type pf malware is seen more as a nuisances than been malicious.
Spyware on the other hand are programs that harvest information from your computer. This can include browsing habits and even key strokes. One emerging threat from spyware is the information harvested from the computer can be used in other types of attacks that require a level of social engineering.