MS05-022 is not categorized as virus, worm, Trojan or backdoor. It is a critical vulnerability in MSN Messenger v6.2, which allows arbitrary code to be remotely executed in the vulnerable computer.
This program is vulnerable because it does not handle properly certain specially crafted GIF (Graphic Interchange Format) image files.
If exploited successfully, MS05-022 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.
MS05-022 is exploited by sending a specially crafted emoticon or picture through Messenger.
If you have MSN Messenger v6.2 installed on your computer, it is recommendable to download and apply the security patch for this vulnerability. Click here to access the web page for downloading the patch.