Nov 29, 2005 (10:11 AM EST)
Hackers Circulate Exploit Code For Two Windows Flaws

Read the Original Article at InformationWeek

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Exploits and proof-of-concept samples for two recently disclosed critical Microsoft vulnerabilities are circulating among hackers, security experts warned Tuesday. Users who have not yet patched their systems should do so immediately, several security organizations recommended.

Microsoft is aware of both exploits, but doesn't see a threat. "[We are] not currently aware of active attacks utilizing the exploit code," Microsoft spokesperson Kjersti Gunderson said. According to Microsoft's security research center, neither exploit can be used to install or execute code remotely.

Over the weekend, proof-of-concept code for an October vulnerability in Windows was posted by a researcher known only as "Darkeagle" of the "unl0ck" security group, said Cupertino, Calif.-based Symantec in a warning to users of its DeepSight Threat Management System. The French security vendor FrSIRT posted a "critical" warning on the exploit code, which it published in full.

According to Darkeagle, the sample exploit can bring down Windows 2000 systems (including those fully patched to Service Pack 4) with a denial-of-service attack. Microsoft confirmed that Tuesday. "Initial investigation of the exploit code targeting MS05-051 has also verified that successful exploitation could lead to a denial of service attack and not remote code execution," Microsoft's Gunderson said.

This exploit code works against systems vulnerable to the Microsoft Distributed Transaction Coordinator (MSDTC) vulnerability. MSDTC is code used to coordinate any sort of transaction on multiple servers, such as database queries.

When Microsoft disclosed the vulnerability in its Oct. 11 round of security bulletins and patches, many security analysts predicted that an attack would come in short order. The next day, in fact, an exploit was released, but only to customers of a vulnerability research tool. The researcher credited with the discovery of the flaw said that the bug might lead to a repeat of August's Zotob attack, which brought down thousands of PCs worldwide. However, no such attacks occurred.

Now, however, Symantec is warning users to patch their systems as soon as possible. "[Although] the exploit released will only cause a denial of service…the public release of this tool may increase the likelihood of a more sophisticated exploit being released," the company said in its DeepSight alert.