A week after Apple updated its QuickTime software to version 7.5.5 and its iTunes software to version 8.0, a proof-of-concept exploit for a purported zero-day vulnerability in Apple's newly patched software has been posted at Milw0rm.com.

Someone using the name "Securfrog" has published code that supposedly can be used to crash any Web browser with the QuickTime plug-in. Because of the way QuickTime handles long strings of data, a memory heap overflow can be created.

Securfrog states that remote code execution may be possible as a consequence of this bug.

In an e-mail, Securfrog said that Apple was alerted a month ago but didn't respond, "so full disclosure."

A request to a security vendor to confirm the functionality of this code was not immediately answered.

Apple's QuickTime 7.5.5 patch fixed nine vulnerabilities related to problems with maliciously crafted media files. One, CVE-2008-3624, addresses a heap buffer overflow arising from the way QuickTime handles QuickTime Virtual Reality movie files.

On Monday, Apple issued Mac OS X 10.5.5, a patch for its operating system addressing more than 30 vulnerabilities in Apple and third-party software.

In "0-Day Patch Exposing Vendors (In)security Performance," presented in March at the Black Hat conference in Amsterdam, Stefan Frei, Bernhard Tellenbach, and Bernhard Plattner of the Computer Engineering and Networks Laboratory at the Swiss Federal Institute of Technology found that, while Microsoft's handling of patches has been improving, Apple's response to security has been getting worse.

The researchers said that it seemed that "Apple's security processes and resources cannot cope with the side-effects of the increased popularity of their products."

Managing risk is the top security issue facing IT professionals, according to the 2008 InformationWeek Strategic Security Survey. The survey of 2,000 IT professionals also found that many are concerned with government or industry regulations that may not give adequate guidance on how to comply. You can learn more about the survey by downloading an InformationWeek Analytics report here (registration required).