Guninski finds hole in MS Exchange security

Bulgarian bug hunter Georgi Guninski says a security risk is created in interaction between Microsoft's Internet Explorer, Internet Information Server and Exchange 2000 software

          Bulgarian bug hunter Georgi Guninski said in an advisory Wednesday that a security risk is created in interaction between Microsoft's Internet Explorer (IE), Internet Information Server (IIS) and Exchange 2000 software, potentially baring server directories and e-mail to prying eyes.

          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 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.

          While neither confirming nor denying the security risk on Thursday, a spokeswoman from Microsoft's public relations firm Waggener Edstrom Inc. called Guninski's revelation "irresponsible."

          "Responsible security researchers work with the vendor of a suspected vulnerability issue to ensure that countermeasures are developed before the issue is made public and customers are needlessly put at risk," she said.

          She added that the Microsoft "is thoroughly investigating the report, just as they do with every report they receive of security vulnerabilities affecting Microsoft products." She declined to say when Microsoft would complete its assessment.

          Guninski classifies the hole as high risk. 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."

          Home computer users aren't particularly vulnerable to the potential hole, said Richard Smith, chief technology officer of the non-profit Privacy Foundation in Cambridge, Mass. "Not everybody really runs IIS," he said, noting that IIS is used with Web servers. "The only people that are going to be vulnerable to this are corporations. The concern is that you could send an e-mail with HTML (hyper text markup language) to break into a company's Web server.

          Guninski 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. [See: Windows Media Player 7 opens system for hackers," Jan. 16.]

          Microsoft, in Redmond, Washington, can be reached at +1-425-882-8080 or at Georgi Guninski is at