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An independent security researcher has pinpointed a denial-of-service flaw in Microsofts brand new Internet Explorer 7 Beta 2 Preview just moments after installing the security-centric browser makeover.
Tom Ferris said could hardly believe his eyes when the new browser crashed less than 15 minutes after he started using a homemade fuzz testing tool to poke around for potential security issues.
Ferris, known online as “badpack3t,” found that specially crafted HTML could cause IE7 to crash because “urlmon.dll” does not properly parse the “file://” protocol.
“Ive confirmed a denial-of-service at this point, but Im sure someone malicious could research this some more to control memory at some point to cause code execution,” Ferris said in an interview with eWEEK.
A proof-of-concept demonstration has been published on the Security-Protocols site, along with a screenshot with proof of the browser crash.
On the Internet Explorer blog, Microsoft program manager Tony Chor confirmed the bug causes a browser crash but said initial investigations did not find that it was exploitable by default to elevate privilege and run arbitrary code.
“This bug had already been found during our code review and analysis that is a mandatory part of our development process. It was scheduled to be fixed before our next public release. We do not believe this bug is easily exploitable,” Chor said.
The Redmond, Wash. software maker typically downplays a denial-of-service browser bug that fixes itself when the browser is restarted, but Ferris said its dangerous to assume the risk cannot be escalated with additional research.
“Weve seen in the past where [malicious hackers] took a denial-of-service issue and created a zero day,” he said, citing a case in November 2005 when a U.K.-based group called “Computer Terrorism released a nasty exploit for a bug that was reported simply as a browser crash issue.
Even though the IE7 browser is still in beta, which allows time to fix bugs before the final release, Ferris said something as serious as a potential code execution hole should have been found by Microsofts software engineers.
“This is Beta 2. The next step is full release,” he added. A final release of Internet Explorer 7 for Windows XP is expected sometime during the second half of 2006.
The latest iteration of the beta is meant specifically as a final preview for third-party developers building Web sites or applications that run on Windows XP, and that a second beta version of IE 7 for Windows Vista, the firms next-generation operating system, will also arrive sometime during the first half of this year.
Vista is scheduled to debut sometime before the end of 2006.
Among the features touted by Microsoft in the preview are the added security and privacy controls it has long promised in the software, along with a tabbed browsing interface and expanded tools for application developers.
Editors Note: This story was updated to include information and comments from Microsoft.