Topic: Adobe warns about "extremely critical" exploit

[Samker]

Adobe today warned users that attacks have begun exploiting an unpatched bug in its popular Reader and Acrobat PDF viewing and creation software.

The company issued an advisory on short notice today, saying that it had learned of in-the-wild attacks only on Tuesday: http://www.adobe.com/support/security/advisories/apsa10-02.html

"A critical vulnerability exists in Adobe Reader 9.3.4 and earlier versions for Windows, Macintosh and UNIX, and Adobe Acrobat 9.3.4 and earlier versions for Windows and Macintosh," Adobe's warning read. This vulnerability could cause a crash and potentially allow an attacker to take control of the affected system.

"Adobe is in the process of evaluating the schedule for an update to resolve this vulnerability," the advisory added.

Other than to say that "at this point, [attacks] appear to be limited," Adobe offered little information on the bug today.

But Mila Parkour, the independent security researcher who reported the bug to Adobe on Tuesday, had plenty in a post to her Contagio Malware Dump blog: http://contagiodump.blogspot.com/2010/09/cve-david-leadbetters-one-point-lesson.html

Parkour uncovered a malicious e-mail message with a rogue PDF attachment that urged recipients to open the document. "Want to improve your score? In these golf tips, David Leadbetter shows you some important principles," the message read.

Leadbetter , a well-known golf coach and author on the game, operates more than two dozen golf academies in 13 countries, and claims the title of "master of the art of teaching the golf swing": http://www.davidleadbetter.com/index_about.html

Symantec pegged the threat with a score of 8.5 out of possible 10, while Danish vulnerability tracker Secunia rated the vulnerability as "Extremely critical," its highest-possible threat level: http://secunia.com/advisories/41340

According to a Symantec, the bug is in Reader's and Acrobat's parsing of PDF files that contain malformed TIFF image files. Specifically, said the company in an alert to customers, "the issue occurs due to a heap-memory corruption issue in 'cooltype.dll.'"

CoolType is an Adobe font-rendering technology, similar to Microsoft 's ClearType.

Adobe did not spell out a timetable for patching the Reader/Acrobat zero-day vulnerability, nor did it offer users any ad hoc defensive measures they could employ until a fix is ready.

The next regularly-scheduled patch date for Reader and Acrobat is Oct. 13, but Adobe has been known to issue so-called "out-of-band" emergency updates when active attacks spike.

An Adobe spokeswoman hinted that the latter could easily occur. "With exploit code publicly available, [the current limited-only attack] could change," she said, talking about the exploit that Parkour has posted online.

Parkour has not released the exploit publicly, however, but has password-protected the malicious PDF she discovered, and will release it only to people who e-mail her.

Symantec urged Reader and Acrobat users not to open PDFs from untrusted or unknown senders.

(PCW)

[Samker]

Adobe Blocks PDF Exploit with Microsoft's Help

Microsoft last Friday urged Windows users to block ongoing attacks against Adobe's popular PDF viewer by deploying one of Microsoft's enterprise tools.

Adobe echoed Microsoft's advice , saying the Enhanced Migration Experience Toolkit (EMET) would stymie attacks targeting Reader and Acrobat: http://www.adobe.com/support/security/advisories/apsa10-02.html

Called "scary" and "clever," the in-the-wild exploit went public last week when security researcher Mila Parkour reported it to Adobe after analyzing a rogue PDF document attached to spam. Adobe first warned users Wednesday of the threat, but at the time gave users no advice on how to protect themselves until a patch was ready.

Microsoft stepped in on Friday.

"The good news is that if you have EMET enabled ... it blocks this exploit," said Fermin Serna and Andrew Roths, two engineers with the Microsoft Security Response Center (MSRC) in an entry on the group's blog.

EMET, which Microsoft upgraded to version 2.0 earlier this month, is a stop-gap designed to keep older applications secure until companies upgrade to up-to-date, and theoretically safer, versions of those programs.

The tool lets IT administrators, and consumers willing to take the plunge, switch on several Windows defenses -- including ASLR (address-space layout randomization) and DEP (data execution prevention) -- for applications whose developers didn't turn them on by default.

The newest PDF exploit defeated Windows' DEP by leveraging a dynamic link library, or DLL, used by Adobe in both programs. Usually, ASLR prevents DEP bypassing, but according to researchers and Microsoft, the "icucnv36.dll" library doesn't have ASLR enabled. That gave attackers a way to sidestep both defenses.

Microsoft's Serna and Roths showed how to use EMET: http://blogs.technet.com/b/srd/archive/2010/09/10/use-emet-2-0-to-block-the-adobe-0-day-exploit.aspx to switch on ASLR for Reader and Acrobat in Windows Vista, Windows 7, Server 2008 and Server 2008 R2, blocking the current exploit. A different tactic is needed to protect Windows XP and Server 2003 systems, which don't support what Microsoft called "mandatory ASLR."

Both Microsoft and Adobe admitted that they had had little time to test the impact of the EMET-based workaround. "Due to the time-sensitive nature of this issue, we have only been able to perform a cursory look at the functional compatibility of this mitigation," said Serna and Roths. "We recommend that you also test the mitigation in your environment to minimize any impact on your workflows."

Some researchers have blasted Adobe for poor programming practices, saying that its mistakes left Reader and Acrobat users at risk.

"This time Adobe gives a hand to the attacker," said Prevx researcher Marco Giuliani , talking about the failure to enable ASLR in icucnv36.dll. "Adobe could have easily prevented this type of exploit": http://www.prevx.com/blog/156/New-Adobe-day-exploit-in-the-wild.html

For others, the moment when Adobe launches its next version of Reader, which will include "sandboxing" technology to isolate application processes from one another and from the rest of the machine, won't come too soon.

"New stack overflow in Adobe Reader," said vulnerability researcher Charlie Miller on Twitter last week. "Dear Adobe, when you patch out of band every month, you don't have a patch cycle. Hurry with the sandbox."

Sandboxing is designed to stop malicious code from escaping an application to wreak havoc or infect the computer, or at least make it much more difficult for hackers to do so.

Adobe has not set a patch date for the Reader/Acrobat bug. The programs' next regularly-scheduled security update is slated for Oct. 12, but Adobe has pushed out emergency, or out-of-band, updates several times this year to fix flaws being actively exploited by attackers.

The last time Adobe released a rush patch was Aug. 19, three weeks after Miller talked about a Reader bug at the Black Hat security conference. Google security engineer Tavis Ormandy had privately reported the vulnerability to Adobe before Black Hat.

Microsoft's EMET 2.0 can be downloaded from the company's site: http://www.microsoft.com/downloads/en/details.aspx?FamilyID=c6f0a6ee-05ac-4eb6-acd0-362559fd2f04&displayLang=en

(PCW)