MS07-028 is not categorized as virus, worm, Trojan or backdoor. It is a critical vulnerability in CAPICOM.Certificates, which allows arbitrary code to be remotely executed in the vulnerable computer.
CAPICOM.Certificates is an ActiveX control that provides scripters with a method for encrypting data based on secure underlying Windows CryptoAPI functionality.
If exploited successfully, MS07-028 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 malicious web page and enticing users into accessing it.
If you have CAPICOM installed in your 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.