Workarounds Released for XP SP2 Flaw
Redmond posts an advisory with workarounds for an unpatched denial-of-service flaw in Windows XP Service Pack 2.The Microsoft Security Response Center late Saturday released a security advisory to offer pre-patch workarounds for a denial-of-service flaw in Windows XP Service Pack 2. The companys advisory follows the public disclosure of the vulnerability in Remote Desktop Services, a feature that allows XP users to remotely control computers from another office, from home or while traveling. However, Microsoft is adamant that the flaw is not as serious as some researchers are making it out to be.
"Our investigation has determined that this is limited to a denial of service, and therefore an attacker could not use this vulnerability to take complete control of a system," the advisory read.
Stephen Toulouse, a program manager in the MSRC, used his personal Weblog to clarify public reports that the RDP flaw could pose a code execution threat. To read more about the Microsoft Security Response Center, click here. "Theres been a lot of talk about code execution and that there might be a widespread attack with this. Our analysis has determined this is a denial-of-service situation, which causes the computer to fault and restart," Toulouse said, insisting it would be "exceedingly difficult" to spread some type of automated attack because the feature is not turned on by default. Toulouse added that there has also "been a lot of talk that this could be used against fully updated firewalled SP2 systems. While thats true if you have enabled Remote Desktop, theres nothing wrong with the firewall in Windows XP SP2. If you enable Remote Desktop, it opens the port on the firewall so that you can remotely contact the computer," Toulouse said. "In this case there is no flaw in the firewall itself, unlike what some people are saying, its just that the port is open when you enable Remote Desktop so that you can communicate with the machine remotely," he added. Check out eWEEK.coms for the latest security news, reviews and analysis. And for insights on security coverage around the Web, take a look at eWEEK.com Security Center Editor Larry Seltzers Weblog.
Block TCP port 3389 at the firewall. This port is used to initiate a connection with the affected component. Blocking it at the network perimeter firewall will help protect systems that are behind that firewall from attempts to exploit this vulnerability. On Windows XP and Windows Server 2003, the Windows Firewall can help protect individual machines. By default, the Windows Firewall does not allow connections to this port. Information on how to disable the Windows Firewall exception for Remote Desktop on these platforms can be found here. Disable Terminal Services or the Remote Desktop feature if they are not required. As a security best practice, if these services are no longer required on a system, users should consider disabling them. Disabling unused and unneeded services helps to reduce your exposure to security vulnerabilities. Information on disabling Remote Desktop via Group Policy can be found in this Knowledge Base article. Secure Remote Desktop Connections by using an IP Security policy. Specific configurations would be dependent upon the individual environment. For more information on IPSec, visit this Web site. Secure Remote Desktop Connections by employing a VPN. Again, configurations would be dependent upon the individual environment. See this Web site for more information about VPN connections.