Apple is quietly adding several key anti-hacker security features into its flagship QuickTime media player as part of a deliberate plan to reduce the effectiveness of malicious exploits.

The XPMs (exploit prevention mechanisms) have been fitted into the WIndows and Mac OS X versions of QuickTime 7.4.5, a new update that also patches 11 high-risk security vulnerabilities.

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According to a source familiar with Apple's moves, QuickTime for Windows Vista now features ASLR (address space layout randomization), a security technology that randomly arranges the positions of key data areas to prevent malware authors from predicting target addresses.

ASLR, which has been used by Apple to add code scrambling diversity to Mac OS X Leopard, is used in tandem with additional security features to reduce the effectiveness of exploit attempts.

Several open-source security systems – OpenBSD, PaX and Exec Shield – already implement ASLR in some form. Microsoft has also fitted ASLR into default configurations of Windows Vista.

In addition to ASLR, QuickTime for Windows will also do stack buffer safety checking (Visual Studio 2005's /GS option) and support for hardware NX on Windows Vista.

The security hardening has also extended to QuickTime for Mac OS X, which gets:

1.         Stack buffer safety checking (-fstack-protector to gcc)

2.         Function call hardening, which should prevent some buffer overflows

Security researchers reacted to Apple's move with applause. "That's a pretty big change for a point release," said Dino Dai Zovi, a hacker who has written multiple exploits for QuickTime. "They [Apple] have way more guts than many other software companies to do something like that. Either that, or they are afraid of the backlash if malware starts targeting QuickTime and iTunes in a more serious way.”

Dai Zovi, who used a QuickTime exploit to hack into a MacBook Pro machine at the 2007 CanSecWest security conference, said the decision to enable the use of ASLR and NX on Vista will hamper exploits.

"QuickTime looks like it may have just gotten more difficult. That is definitely a good thing," Zovi said.