MS07-006 is not categorized as virus, worm, Trojan or backdoor. It is an important 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, MS07-006 allows to gain unauthorized privileges on a computer or network. An example of privilege elevation would be an unprivileged user who could manage to be added to the Administrator's group. In such case, 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 executing a specially crafted application in the vulnerable system. However, in order to do so, the user must be authenticated.
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 the previous bulletin, called MS06-045.