Adobe on Thursday patched two vulnerabilities in its popular Reader PDF viewing software, including one that went public last month at the annual Black Hat security conference.
Two weeks ago, Adobe promised to fix the Black Hat vulnerability with an emergency, or "out-of-band" security update; earlier this week it set today as the release date.
That vulnerability was disclosed by researcher Charlie Miller at July's Black Hat event in Las Vegas, where he demonstrated how the open-source BitBlaze toolkit could boost bug-hunting productivity. Miller, an analyst with Baltimore-based Independent Security Evaluators and a well-known vulnerability researcher, said the bug was in Reader's and Acrobat's font parsing.
Adobe knew of the bug before Miller took it public, however, as another researcher -- Google security engineer Tavis Ormandy -- had previously reported the vulnerability. Today Adobe credited Ormandy, not Miller, with finding the flaw.
In Thursday's advisory , Adobe classified both Ormandy's bug and another vulnerability patched today as critical, noting that each "could lead to code execution," phrasing that means attackers could exploit them to compromise a machine.
As is Adobe's practice, it revealed only the scantiest of details about the bugs. The second vulnerability was only described as one that "further mitigate[s] a social engineering attack."
What Adobe failed to mention was that it had patched that bug before.
First fixed in late June when Adobe last updated Reader and Acrobat, the bug tagged as CVE-2010-1240 popped into public view last March when Belgium researcher Didier Stevens showed how a multi-stage attack using the PDF specification's "/Launch" function could successfully exploit Reader. Stevens also showed how a Reader warning could be changed to further fool users.
Hackers used Stevens' technique in mass attacks for several months before Adobe issued the update on June 29. Like today's, that update was "out-of-band," having been pushed up from an already-scheduled July 13 release date.
Today's updates to versions 9.3.4 and 8.3.4 of Reader and Acrobat also included patches released last week for Flash, Adobe's media player. Both Reader and Acrobat include code to run Flash embedded in PDF documents.
Adobe Reader and Acrobat for Windows, Mac and Linux can be downloaded using the links included in Thursday's advisory . Alternately, users can use the programs' built-in update mechanism to grab the new versions.
Last April, Adobe activated an automatic update mechanism included with recent versions of Reader and Acrobat; users must manually switch on the automatic updating, however.