MS06-026 is not categorized as virus, worm, Trojan or backdoor. It is a critical vulnerability in the Graphics Rendering Engine on Windows Me/98 computers, which allows arbitrary code to be remotely executed in the vulnerable computer.
If exploited successfully, MS06-026 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 specially crafted WMF (Windows MetaFile) image in a web page and enticing users into accessing it, or by sending via email a specially crafted message that contains a WMF image.
However, it is possible to create a malicious WMF image and change its extension to other graphic extension (JPG, BMP, ICO, etc.), and the vulnerability could also be exploited in the same way.
If you have a Windows Me/98 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.