Worm targeting Windows vulnerability spreads rapidly

A worm exploiting a recently announced vulnerability in many Microsoft Windows operating systems is quickly infecting thousands of unprotected computers.

The vulnerability could let attackers execute code on exploited machines. The MSBLAST worm apparently carries a payload that will launch a distributed denial-of-service attack against Microsoft's update site beginning Aug. 16.

Microsoft announced the vulnerability and on July 16 released a patch to correct it. The Remote Procedure Call Distributed Component Object Model buffer overflow affects Windows NT, 2000 and XP. Because the vulnerability is so widespread, Microsoft has identified it as a critical problem.

Although the patch has been available for more than three weeks, security vendors reported today that the MSBLAST worm was spreading rapidly.

'Symantec Corp. has identified that over 57,000 systems have been infected and are currently launching probes against port 135,' the Cupertino, Calif., company said in a statement. 'This number has grown exponentially in the last 24 hours.'

According to an analysis by Internet Security Systems Inc. of Atlanta, the worm randomly scans IP addresses from infected machines to find other vulnerable computers. When a target is found, the exploit is launched and the newly infected machine connects back to the scanning machine to obtain the worm binary.

The binary is an executable file apparently set to launch the attack against Microsoft beginning Aug. 16.

Systems can be protected by patching as described in Microsoft Security Bulletin MS03-026. The bulletin and the patch are available from the Microsoft Web site.

Security vendors also recommend monitoring and blocking traffic on TCP port 135, which is used to propagate the worm, and UDP port 69, which is used to download the worm binary to infected machines.

About the Author

William Jackson is a Maryland-based freelance writer.


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