MS05-040 is not categorized as virus, worm, Trojan or backdoor. It is an important vulnerability in the Telephony service in Windows 2003/XP/2000, which allows arbitrary code to be remotely executed in the vulnerable computer or local elevation of privilege.
If exploited successfully, MS05-040 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.
Depending on the operating system under attack, several requirements must be fulfilled to compromise the computer:
- On Windows 2000 Server, any user can remotely exploit the vulnerability by sending an specially crafted packet. Such computers must have been previously configured as telephony servers.
- On Windows 2003 Server, the Telephony service is restricted to authenticated user accounts. Thus, such packets must be sent by an authenticated user. These computers must have been previously configured as telephony servers.
- On Windows XP, Windows 2000 Professional and on the computers that are not configured as telephony servers, it is necessary that the user runs a specially crafted application in order to obtain local elevation of privilege.
Attacks can be launched across the Internet, but a firewall could be used in order to prevent those attacks.
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.