Buffer the Overflow Slayer v. the ActiveX Files

Flashpix nix 'safe for scripts'

homeless man with sign

Microsoft's DirectX Media software development kit may be doing a lot more than helping designers give a realistic flesh tone to Lara Croft's breasts. It could also be introducing critical vulnerabilities into a countless number of applications that are spawned by the SDK.

That's because the SDK, which streamlines much of the work of building graphic-intensive video games and applications, contains a third-party ActiveX control that's vulnerable to a buffer overflow. Labeled DirectTransform FlashPix and provided by the Live Picture Corporation, it leaves applications vulnerable to attacks that allow for the remote execution of code.

An attacker would still have to lure a victim running FlashPix to a visit booby-trapped website or open a maliciously crafted email. But hey, we're talking about virtual worlds and multi-player video games, where people consort with strangers all the time.

"This is worse than your average social engineering situation," says security researcher Rodney Thayer. "If you're in a gaming environment where you're trying to get the dwarf to talk to you in English, you may actually listen to people who give you advice."

Internet Explorer can also be used as an attack vector, because FlashPix is labeled as "safe for scripting".

The vulnerability was discovered by Krystian Kloskowski and is rated "highly critical" in this posting on Secunia. It's also discussed here on the US-Cert website. Proof-of-concept code can be found on MilW0rm here.

The flaw comes courtesy of a boundary error in Live Picture's DXSurface.LivePicture.FLashPix.1, which translates to the DXTLIPI.DLL file on Windows machines. It can be exploited to cause a buffer overflow by assigning excessive strings to the affected property.

Workarounds include setting the kill-bit for the FlashPix control(CLSID {201EA564-A6F6-11D1-811D-00C04FB6BD36}) or disabling all ActiveX controls in the Internet zone.

A Microsoft spokesman said the company's security team is investigating the report and is unaware of any attacks using the claimed vulnerability. ®

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