Internet security is an often talked about issue on news sites and blogs all over the Internet. Downloaded files can often be a cause of security compromises when bundled with viruses and malware designed to cause damage. Sometimes, it is not always obvious when a file contains a malicious component.
A Trojan (often called a Trojan horse) is a malicious program designed to deceive the user into believing it is legitimate software. Trojans do not replicate themselves like other viruses and worms do but once executed are able to carry out their malicious intentions. Trojans install what is known as a "payload", which could be as innocent as a text window or serious enough to cause harm to personal and system files.
Trojans in WMV Files
Since Windows Media Player became more advanced, features have been added that some have been able to exploit. It is possible to bundle a Trojan within a Windows Media Video (WMV) file, which will claim to download a license from the Internet but instead installs unwanted software such as adware (nuisance advertising on screen) and dialers (programs that dial premium-rate dial-up numbers). Two such strains of Trojan which made use of this exploit were the "Trj/WmvDownloader.A" and "Trj/WmvDownloader.B" infections in 2005.
Types of Trojan
There are three main categories of Trojan: remote access (or back-door access), IRC Trojans and key-loggers. Remote access Trojans often install code that allows a computer to be remotely controlled by a user. Many remote access Trojans are used to conduct distributed denial of service (DDoS) attacks without users ever being aware. IRC Trojans were originally spread over Internet relay chat and key-loggers have been used to log key presses and gain sensitive information for years. Many of these Trojans will often be bundled together in the same package.
To prevent your PC becoming infected with a Trojan either from a WMV or any other file, ensure you download only from trusted sources. Be aware of malicious files within email attachments and never open a file if you can't be sure who sent it or what it is. Using an anti-virus or similar software package will help scan and remove infections found on your PC.
Anti-Virus and Other Software
Installing an anti-virus program can greatly reduce the risk of infection on your PC. The software scans files periodically while your computer is running to make sure there are no infected files present. Some free solutions include AVG Anti-Virus Free Edition, Avira AntiVir Personal and Avast! Free. Other software that can also detect Trojans and its associated malware include scanners for adware and spyware. Lavasoft's Ad-Aware Personal, Spybot Search & Destroy and Microsoft's AntiSpyware tool are all free solutions to help remove Trojans and their payload.
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