FRAMINGHAM (01/11/2012) – Adobe on Tuesday patched six vulnerabilities in the newest version of its popular Reader PDF viewer, making good on a late-2011 promise when it shipped an emergency update for an older edition.
That update addressed bugs that attackers had exploited with rigged PDF documents emailed to a large number of companies, including major U.S. defense contractors last December, probably as part of an effort to steal confidential information. Researchers found clues in the attack tactics and exploit code that pointed to Chinese hacker involvement.
While Adobe patched Reader 9 on Windows almost a month ago, it deferred updates for Reader 10 on all platforms, and for Reader 9 on Mac and Linux. The exploits would fail if aimed at Reader 10 because of that version’s protective “sandbox” technology, Adobe said, and Mac and Linux users were in little danger because attackers were focused on Windows PCs.
Tuesday’s update patched not only the two known bugs but also four others. Adobe rated all six as critical, saying in an accompanying advisory that they could give hackers the openings necessary to hijack a computer or infect it with malware.
The four previously-undisclosed bugs were reported by researchers from Google’s security team, the Danish vulnerability tracking firm Secunia and HP TippingPoint’s bug bounty program.
The most up-to-date edition for Linux, version 9.4.7, includes patches for just the two vulnerabilities disclosed last month.
Those already-being-exploited vulnerabilities had been reported to Adobe by Lockheed Martin, one of the U.S’s largest aerospace and defense contractors, and the Defense Security Information Exchange (DSIE), a group of defense contractors that share cyber-attack intelligence.
Adobe also added a new security feature to Reader 9.5 and 10.1.2 — the designations for the patched versions released Tuesday — that lets company IT administrators disable JavaScript in some PDFs while allowing it to function in others.
According to Steve Gottwals, Reader’s group product manager, the new “whitelisting” feature allows administrators to switch off JavaScript in all PDFs except those that are designated as “trusted.”
“If a document is trusted, JavaScript execution will be allowed; but if it is untrusted, Adobe Reader and Acrobat will prevent all JavaScript execution,” said Gottwals in a blog post yesterday. “The trust decision is based on Privileged Locations.”
Previously, administrators could only switch JavaScript on or off.
Security experts applauded the additional flexibility Tuesday.
“The better manageability lets you turn [JavaScript] off, but allows it to work on documents from certain sites, like those within the organization,” said Wolfgang Kandek, chief technology officer at Qualys. “I think it’s a very useful feature for enterprises.”
JavaScript has been the source of numerous Reader vulnerabilities over the years, and has remained a common way for hackers to compromise PCs, plant malware and steal information via malicious PDFs.
Several of the emergency patches Adobe issued for Reader in 2010, for instance, were due to JavaScript vulnerabilities, while as long ago as 2008, one researcher said Adobe suffered from an “epidemic” of JavaScript bugs.
Both Reader 9.5 and Reader 10.1.2 on Windows and Mac OS X include the new JavaScript whitelisting feature; however, version 9.4.7 for Linux does not.
The updated editions of Reader for Windows and Mac OS X can be downloaded from Adobe’s support website. Current users can run the programs’ integrated update tool or wait for the software to prompt them that a new version is available.
