Microsoft on Monday said it is looking into a report of a flaw in some versions of its Internet Information Services product that could allow an attacker to gain control of a system.
In a statement, a Microsoft representative said the company "is investigating new public claims of a possible vulnerability in IIS 5 and IIS 6 File Transfer Protocol (FTP)."
Microsoft said it is not aware of any attacks using the vulnerability. "We will take steps to determine how customers can protect themselves, should we confirm the vulnerability."
According to IDG News Service, code for exploiting the unpatched flaw was posted to the Milw0rm Web site. IDG said the exploit appears to affect primarily older versions of IIS--and only when the FTP function is enabled.
Once it is done with its investigation, Microsoft said, it will decide how to address the matter, which could include a security update as part of its monthly Patch Tuesday or an out-of-cycle update.
In a posting on Monday, the U.S. Computer Emergency Readiness Team (US-CERT) suggested IT administrators "disable anonymous write access to the FTP server to help mitigate the vulnerability" but added that "a proper impact analysis should be performed prior to taking defensive measures."