MS06-057 is not categorized as virus, worm, Trojan or backdoor. It is a critical vulnerability in the Windows Shell on Windows 2003/XP/2000 computers, which allows arbitrary code to be remotely executed in the vulnerable computer.
If exploited successfully, MS06-057 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 exploited by creating a specially crafted web page and enticing users into accessing it with Internet Explorer. In general, any way to deliver web content to vulnerable computers could be used, such as banner advertisements, for example.
If you have a Windows 2003/XP/2000 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.
Additionally, bear in mind that this security bulletin replaces a previous bulletin, called MS06-045, but only for Windows XP Service Pack 1.