Adobe patches 8 bugs in popular PDF apps

Fifth update to Reader this year fixes JavaScript flaw, other bugs

Adobe Systems Inc. today patched its Reader application for the fifth time this year, plugging eight security holes, including one that was reported to the company more than five months ago.

In late May, researchers at Core Security Technologies told Adobe of a critical vulnerability in Adobe Reader and Adobe Acrobat, the free-of-charge and for-a-fee programs, respectively, that handle PDF files. The bug, which could be used by hackers to launch attack code against Windows, Mac or Linux computers, was found in older versions of the software.

Versions 8.1.2 of Acrobat and Reader harbor the vulnerability, Core Security said in an advisory issued early today. Newer versions of the programs, Acrobat 9 and Reader 9, which were released in June, are immune.

Attackers could exploit the buffer overflow vulnerability with specially crafted PDF files, Core Security said.

Reader 8.1.2 was itself plagued by several bugs, some of which were actively exploited in the wild before Adobe could issue the update last February. In June, Adobe released a security update to 8.1.2 to plug yet another hole. That vulnerability had also been exploited by attackers before Adobe reacted.

At the time, a security expert blasted Adobe for what he called an "epidemic" of JavaScript bugs in Reader and Acrobat.

The flaw disclosed today by Core Security also involved JavaScript. "The vulnerability is caused due to a boundary error when parsing format strings containing a floating point specifier in the 'util.printf()' JavaScript function," said Core Security's advisory.

Core Security uncovered the bug when it dug into an earlier-reported vulnerability in Foxit Reader, a free Reader clone available for Windows and Linux. Although that bug was found to be harmless to Adobe's applications, on further review, Core Security found a second flaw that could, in fact, be used to attack systems.

Core Security reported its findings to Adobe on May 20, but numerous back-and-forths between Core Security and Adobe and two patch postponements delayed the coordinated release of security advisories until today.

Ironically, while Foxit Software Co. was able to patch the bug in its software in less than a month, Adobe took more than five times longer to issue fixes for its Acrobat and Reader. Ivan Arce, Core Security's chief technology officer, declined to speculate about why Adobe took so long to patch its programs, other than to point out that today's update fixed eight flaws altogether.

As to the frequent patching Adobe has had to do on the programs, particularly to quash JavaScript-related bugs, Arce had an opinion, however. "Reader is huge, and it has a lot of functionality," he said today. "Big and complex software tends to have more implementation bugs than simple and easy-to-maintain software."

Shortly after Core Security published its advisory, Adobe followed with its own. The advisory offered links to updates to Reader 8.1.3 and Acrobat 8.1.3, and it included terse descriptions of the other seven vulnerabilities patched today, which included additional input validation bugs, a pair of flaws in Reader's download manager and a vulnerability that had been published publicly last May.

Adobe said it had no reports of active attacks using any of the eight vulnerabilities, something Core Security echoed for the flaw it had reported. "We told them, 'Look, this is fine, we'll wait for your patch,'" said Arce, referring to conversations with Adobe when the vendor postponed its patch. "But we said, 'If we detect it in the wild, we'll release [our advisory] so people will know what to do.' So far we haven't seen any attacks."

Users running Adobe Reader or Acrobat 9 don't need to take any action to protect their machines.

Copyright © 2008 IDG Communications, Inc.

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