Adobe has 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.
Security experts applauded the additional flexibility Tuesday.
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.