Updated Engineers on Thursday patched a hole in Adobe's ubiquitous Flash Player that allowed website operators to silently eavesdrop on visitors' webcam and microphone feeds without permission.
To be attacked, visitors needed to do no more than visit a malicious website and click on a handful of buttons like the ones in this live demonstration. Without warning, the visitor's camera and microphone were activated and the video and audio intercepted. The attack closely resembled a separate Flash-based attack on webcams from 2008 using a class of exploit known as clickjacking.
Adobe said on Thursday it was planning to fix the vulnerability, which stems from flaws in the Flash Player Settings Manager. The panel, which is used to designate which sites may access feeds from an enduser's camera and mic, is delivered in the SWF format used by Flash. Feross Aboukhadijeh, a computer science student at Stanford University, discovered he could embed the SWF file as an invisible iframe and superimpose misleading graphics on top that tricked visitors into making changes to the underlying privacy settings.
“I've seen a bunch of clickjacking attacks in the wild, but I've never seen any attacks where the attacker iframes a SWF file from a remote domain to clickjack it – let alone a SWF file as important as one that controls access to your webcam and mic!” Aboukhadijeh wrote in a blog post.
Because the settings manager is hosted on Adobe servers, engineers were able to close the hole without updating enduser software, company spokeswoman Wiebke Lips said. The change was pushed out early in the afternoon on Thursday, two days after Aboukhadijeh published his findings.
Shortly after security researchers Jeremiah Grossman and Robert “RSnake” Hansen documented clickjacking in 2008, Adobe patched Flash to blunt attacks that exploited the program to surreptitiously spy on the millions of people who use it. Engineers closed the hole by changing the behavior of Flash security dialog box when it's set to be transparent.
Aboukhadijeh was able to revive the attack by exploiting the settings manager, which until Thursday's fix, still allowed important settings to be made while it was in transparent mode.
He said his demonstration worked only against Macs when using Firefox or Safari, and that a CSS opacity bug prevented it from working on other operating systems and browsers. It wouldn't have been surprising if additional research uncovered ways to make the attack more universal.
Aboukhadijeh went on to say he went public after reporting the vulnerability to Adobe and getting no reply.
“It's been a few weeks and I haven't heard anything from Adobe yet,” he said. “I think it's worth sharing it with the world now, so that Adobe pays attention and fixes it more quickly.” ®
This article was updated throughout to reflect that Adobe has issued a patch.