Adobe confirms PDF zero-day, plans rush patch

Will go 'out-of-band' with fix, probably on Aug. 17

Adobe today said it would issue an emergency patch the week of Aug. 16 to fix a critical flaw in its Reader and Acrobat software.

The bug was disclosed by researcher Charlie Miller at last month's Black Hat security conference when he demonstrated how the open-source BitBlaze toolkit could be used to boost bug-hunting productivity 10-fold.

Miller, an analyst with Baltimore-based Independent Security Evaluators, is well-known for finding vulnerabilities in Adobe's popular Reader PDF viewer. Last March, Miller showed how a simple fuzzing tool could root out scores of potential bugs in Reader, Microsoft Office, Apple's Preview and other software.

According to a paper Miller published after the Black Hat conference (download PDF), and others, the bug is in Reader's and Acrobat's font parsing.

"This can be exploited to corrupt memory via a PDF file containing a specially-crafted TrueType font," stated Danish vulnerability tracker Secunia in an advisory published Wednesday. "Successful exploitation may allow execution of arbitrary code."

Today, Adobe announced it would release a rush, or "out-of-band" security update during the week of Aug. 16-20. Adobe issues its quarterly security updates for Reader and Acrobat on Tuesdays, and has shipped emergency fixes on that same day of the week. If the company continues the practice, it would most likely deliver the out-of-band patch on Aug. 17.

Adobe hinted that the out-of-band update will include fixes for vulnerabilities other than the one Miller uncovered. The company also said it would still ship its next regularly-scheduled quarterly update on Oct. 12.

Although the Adobe vulnerability shares traits with the one currently being used to "jailbreak" Apple's iOS mobile operating system -- both involve font parsing errors -- they're not linked, Miller said.

"Its just a coincidence that they are both bugs in the way programs parse fonts in PDFs," Miller said in an e-mail reply to questions.

The vulnerability exploited by the JailbreakMe software is in Apple's PDF viewer, dubbed Preview, not in Adobe's Reader, a fact that Adobe tried to make clear yesterday. "Not all PDF-related vulnerabilities are automatically Adobe vulnerabilities," argued Brad Arkin, Adobe's head of security and privacy, pointing out that the formerly proprietary PDF was issued as an open standard in 2008.

Adobe has issued several out-of-band updates this year for Reader. Adobe last released an emergency Reader update in late June when it moved up the already-scheduled July 13 fixes by two weeks to deal with a bug hackers were already exploiting. It also rushed a Reader fix to customers in February.

The push to come up with a fix for the latest Reader zero-day will not affect work on the next major upgrade to the program, Adobe said today. Reader 10, which should ship for Windows before the end of the year, is to include "sandboxing" technology to isolate malicious PDF documents -- such as the kind that might leverage Miller's vulnerability -- so that they can't infect the PC.

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@ix.netcom.com.

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