A virus is a file written with the sole intention of doing harm, or for criminal activity. There are many types of virus. Viruses and spyware are also known as ‘malware’
A worm, for example, can exploit security vulnerabilities to spread itself automatically to other computers through networks. A Trojanhorse (or simply ‘Trojan’) is a program that appears harmless but hides malicious functions. Zeus (and its derivatives such as Gameover Zeus) is an example of a Trojan, capable of being used to carrry out many malicious and criminal tasks. Viruses may harm a computer system’s performance or data. Some are noticeable to the computer user, but many run in the background, unnoticed by the user. A virus may be designed to replicate itself.
Potentially, a virus could arrive on your computer in the form of a Trojan, it could replicate itself before moving on to another computer (a worm) and also be designed as a piece of spyware. Viruses and spyware are types of malware, which also includes rootkits, dishonest adware and scareware.
Viruses and spyware can attack your computer via the following means:
- Opening infected email attachments such as .exe files.
- Opening infected files from web-based digital file delivery companies (for example Hightail – formerly called YouSendIt, and Dropbox).
- Visiting corrupt websites.
- Via the internet, undetected by the user (worms are an example of this).
- Macros in application documents (word processing, spreadsheets etc).
- USB connected devices (eg memory sticks, external hard drives, MP3 players).
Viruses and spyware can cause very serious consequences including:
- Identity theft.
- Deletion, theft and corruption of data.
- A slow or unusable computer.
Internet security (antivirus/antispyware) software
It is vital to keep your internet security software up to date in order to provide the most complete protection. Thousands of new viruses are detected every day, to say nothing of the variants of new and existing ones. Each has a set of characteristics or ‘signatures’ that enable internet security software manufacturers to detect them and produce suitable updates.
Most internet security software automatically downloads these updates (sometimes referred to as ‘definitions’) on a regular basis, as long as you are online and have paid your annual subscription (for a paid-for product). This should ensure protection against even the latest virus threats.