Feeds

Adobe mulls changes to close hole in PDF apps

'Powerful functionality' v 'potential risks'

Securing Web Applications Made Simple and Scalable

Adobe Systems may make changes to its widely used PDF programs to prevent attackers from using them to mount attacks that hijack users' computers.

The attack was first demonstrated last week by researcher Didier Stevens. By misusing a feature contained in the PDF specification, his proof-of-concept attack showed how hackers could embed a malicious payload in a document and trick Adobe's Reader and Acrobat applications - as well as the competing FoxIT Reader - into executing it.

While Adobe applications warn users they are about to execute a potentially dangerous program, Stevens showed it was possible to modify the wording, increasing the attacker's chances of successfully socially engineering his victim.

Fellow security researcher Jeremy Conway soon adapted the technique to devise an attack that would allow a malicious payload stashed in one PDF file to spread to another document. A few days later a blogger who goes by the handle YunSoul, modified the attack further, showing how a single malicious PDF could infect an unlimited number of documents.

Steve Gottwals, a member of Adobe's security team, said it is in the process of reviewing the automatic launch feature in light of the new information.

"This is a good example of powerful functionality relied upon by some users that also carries potential risks when used incorrectly by others," he wrote. He went on to say: "We are currently researching the best approach for this functionality in Adobe Reader and Acrobat," and it may introduce changes in a future update.

In the meantime, users who have no need for the automatic launch feature (and we're guessing this is 90 percent or more of them) can mitigate the threat by modifying their Reader or Acrobat preferences. To do this, go to Edit > Preferences and click on Trust Manager in the left pane. Then, uncheck the box for "Allow opening of non-PDF file attachments with external applications."

System administrators managing large numbers of PCs can make the change en masse by modifying registry settings as further described here.

Conway told The Register that the mitigation neutralizes the recent attacks demonstrated by him and the other researchers. But it won't close the hole completely, he said. A separate PDF specification that allows applications to keep track of revisions could still be used to inject harmful code into PDFs using other types of programs.

"Anything that has write access can perform an incremental update," said Conway, who is a program manager for New Hampshire-based Nitrosecurity. "It stops the attack vector of using the launch command, but it doesn't fix the incremental update issue." ®

Mobile application security vulnerability report

More from The Register

next story
HIDDEN packet sniffer spy tech in MILLIONS of iPhones, iPads – expert
Don't panic though – Apple's backdoor is not wide open to all, guru tells us
NEW, SINISTER web tracking tech fingerprints your computer by making it draw
Have you been on YouPorn lately, perhaps? White House website?
LibreSSL RNG bug fix: What's all the forking fuss about, ask devs
Blow to bit-spitter 'tis but a flesh wound, claim team
Black Hat anti-Tor talk smashed by lawyers' wrecking ball
Unmasking hidden users is too hot for Carnegie-Mellon
Manic malware Mayhem spreads through Linux, FreeBSD web servers
And how Google could cripple infection rate in a second
NUDE SNAPS AGENCY: NSA bods love 'showing off your saucy selfies'
Swapping other people's sexts is a fringe benefit, says Snowden
Own a Cisco modem or wireless gateway? It might be owned by someone else, too
Remote code exec in HTTP server hands kit to bad guys
prev story

Whitepapers

Reducing security risks from open source software
Follow a few strategies and your organization can gain the full benefits of open source and the cloud without compromising the security of your applications.
Consolidation: The Foundation for IT Business Transformation
In this whitepaper learn how effective consolidation of IT and business resources can enable multiple, meaningful business benefits.
Application security programs and practises
Follow a few strategies and your organization can gain the full benefits of open source and the cloud without compromising the security of your applications.
Boost IT visibility and business value
How building a great service catalog relieves pressure points and demonstrates the value of IT service management.
Consolidation: the foundation for IT and business transformation
In this whitepaper learn how effective consolidation of IT and business resources can enable multiple, meaningful business benefits.