MS10-055 is not categorized as virus, worm, Trojan or backdoor. It is a critical vulnerability in the Cinepak codec on Windows 7/Vista/XP computers, which allows arbitrary code to be remotely executed in the vulnerable computer.
If exploited successfully, MS10-055 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 creating a media file with a specially crafted AVI file embedded in it and sending it via email to the users. It could also be exploited by hosting a website that contains specially crafted content and enticing users to access it. The link to the malicous website can be distributed via email or instant messaging programs.
If you have a Windows 7/Vista/XP 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.