MS08-054 is not categorized as virus, worm, Trojan or backdoor. It is a critical vulnerability in Windows Media Player version 11 on Windows 2008/Vista/XP computers, which allows arbitrary code to be remotely executed in the vulnerable computer.
If exploited successfully, MS08-054 allows hackers to gain remote control of the affected computer with the same privileges as the logged on user. If this user had administrator rights, the hacker could take complete control of the system: create, modify or delete files, install programs, create new user accounts, etc.
This vulnerability is usually exploited by hosting a Windows Media Server that contains a specially crafted audio file and enticing users to visit a malicious website. The link to that website can be distributed by the usual means, such as email, instant messaging programs, etc.
If you have Windows Media Player version 11 installed on your computer, it is recommended to download and apply the security patch for this vulnerability. Click here to access the web page for downloading the patch.