Hackers exploit newest Flash zero-day bug

Adobe today confirmed that hackers are exploiting a critical unpatched bug in Flash Player, and promised to patch the vulnerability in two weeks.

The company issued a security advisory that also named Adobe Reader and Acrobat as vulnerable.

“There are reports that this vulnerability is being actively exploited in the wild against Adobe Reader and Acrobat,” said Adobe in its warning. The company said it’s seen no sign that hackers are also targeting Flash Player itself.

Those reports came from Mila Parkour, an independent security researcher who notified Adobe early today after spotting and then analyzing a malicious PDF file. According to Parkour, the rigged PDF document exploits the Flash bug in Reader, then drops a Trojan horse and other malware on the victimized machine.

Adobe said that all versions of Flash on Windows, Mac, Linux, and Android harbored the bug, and that the “Authplay” component of Reader and Acrobat 9.x and earlier also contained the flaw. Authplay is the interpreter that renders Flash content embedded within PDF files.

Last month, Parkour uncovered a bug in Reader’s font-rendering technology that was exploited by attack campaigns using bogus messages from renowned golf coach David Leadbetter as click bait.

Today’s vulnerability, however, is more reminiscent of one reported in June that also involved Authplay. Adobe issued an emergency patch for Flash Player within a week, and followed with a fix for Reader and Acrobat two weeks later.

Adobe will patch this newest bug in a similar fashion. Today it promised to issue a fix for Flash by Nov. 9, and updates for Reader and Acrobat the following week.

Danish vulnerability tracker Secunia ranked the Flash flaw as “extremely critical,” its highest threat ranking, and said criminals could use it to compromise systems and execute malicious code.

Security experts have regularly criticized Adobe Flash’s security, with some questioning the company’s decision to integrate the media player’s capabilities within the almost-as-popular Reader. Adobe has countered those arguments with its own, saying that many users rely on the functionality.

Until a patch is available, Windows users can protect themselves from active attacks by deleting the “authplay.dll” file that ships with Reader and Acrobat; Mac users can instead remove an AuthPlayLib.bundle file from a location specified in Adobe’s security bulletin above. The company gave the same advice in June when the earlier Flash vulnerability was reported.

Dumping authplay.dll, however, will crash Reader and Acrobat or produce an error message when the software opens a PDF file containing Flash content.

Today’s Flash flaw disclosure was the second Adobe’s acknowledged since the technology was ported to Google’s Android operating system two months ago.

Although Adobe tries to hew to a quarterly patch schedule for Reader and Acrobat, it’s repeatedly been forced to scuttle those plans to issue rush fixes for critical bugs. The next regularly-scheduled Reader update was not supposed to land until Feb. 8, 2011.

At times, Adobe has abandoned scheduled Reader updates after shipping an “out-of-band” patch, but that’s unlikely here as the company is in the early days of its next patch cycle.

Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer or subscribe to Gregg’s RSS feed . His e-mail address is gkeizer@computerworld.com.

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