Microsoft is investigating reports of a vulnerability in its popular web server Internet Information Services (IIS), which could allow an attacker to access password-protected files.
In its advisory, Microsoft said that "an elevation of privilege vulnerability exists in the way that the WebDAV extension for IIS handles HTTP requests".
Microsoft said it was investigating public reports of the problem, but so far wasn't aware of attacks that tried to use the vulnerability or of any customer impact.
The United States Computer Emergency Readiness Team (US-CERT) said it was already aware of publicly available exploit code and active exploitation of the flaw.
Security researcher Nikolaos Rangos said exploitation of the flaw could allow an attacker to get into password-protected folders, as well as allow the listing, downloading and uploading of files into a password-protected WebDav folder.
Security engineer Thierry Zoller has more details on the vulnerability, and warned that until the impact was 100 per cent clear, administrators should disable WebDav.
Last year, Microsoft denied there was any vulnerability in IIS after a a massive SQL injection attack had affected hundreds of thousands of web pages.
