The advisory said Microsoft's OLE DB for Internet publishing program, a tool used to help Web-publish information stored in databases, gives a scripting interface for accessing and manipulating objects on IIS 5.0 or in Web storage. "The problem is it allows connecting to arbitrary servers, not only to the server from which the HTML (Hypertext Markup Language) page is loaded," Guninski said in the advisory.
Additionally, if the IIS 5.0 is in the local intranet zone of IE versions 5.0 and higher, the browser, by default, automatically authenticates it, without prompting the user, Guninski wrote.
Guninski classifies the hole as high risk. A Microsoft representative was not immediately available to confirm the report. Guninski said in the report that he had alerted Microsoft to the problem, and that the company replied that, "visiting malicious Web sites is not a real exploit scenario".
A hacker hoping to exploit the hole would have to create a malicious Web page in order to peek at server directories, Guninski wrote. It is possible to list the directories of arbitrary IIS 5.0 servers to which the browsing user has access. "Under certain circumstances it is also possible to read the user's e-mail or folders if it is stored on an Exchange 2000 server with Web storage," he wrote. "It is also possible to create (or probably modify) files on the Exchange 2000 server with Web storage."
He recommended users disable Active Scripting to solve this particular issue.
Guninski discovered several vulnerabilities in Microsoft software last year. His most recent discovery was of a security vulnerability in Microsoft's Windows Media Player 7 reported in January, a problem with the player's "skins" -- custom decorations for the Graphical User Interface -- potentially allowing a hacker to get full control over a user's computer.