Feeds

Facebook summarily denies undeniable user-menacing security hole

'It doesn't exist...bitch'

Top 5 reasons to deploy VMware with Tegile

Exclusive Facebook's hip new application platform contains a gaping hole that allows attackers to run malicious javascript on unsuspecting users' machines, a developer has demonstrated.

Proof of concept code examined by El Reg shows how the platform can be used to steal Facebook user's session identification cookies, deliver pop-up messages or change the layout of Facebook pages. With a little extra work, an attacker could probably do much more, including send and read messages from a user's account, change privacy settings and add or delete Facebook friends.

"This is quite a big security hole," said Artur Wachelka, a Munich-based developer of online games who stumbled upon the bug while writing a chess game for Facebook. He said he decided to take the vulnerability public after reporting it to Facebook privately and receiving a single sentence reply that the security issue didn't exist.

Evidently the Facebook drone didn't bother to run the Wachelka's proof-of-concept code. It clearly shows that javascript can be executed on on a browser to display session cookies, display a pop-up windows that says "Oooops" and even change the color of the Facebook banner.

A Facebook spokeswoman said members of the company's security team were investigating the report. As of Monday afternoon, the bug had yet to be squashed.

The bug exists in a component of what's known as FBML, short for Facebook markup language, which developers can use to write games and other applications that run on Facebook. For reasons that aren't clear, a tag that translates text from one language to another fails to parse input for javascript before sending it to users' browsers. The bug appears to work only on Facebook's recently updated pages, and only after users have logged in to their accounts.

Screenshot showing Facebook app that grabs session cookie

All your Facebook session cookies are belong to us

Wachelka said he filed a bug report with Facebook on Friday and promptly received a message saying the matter had been closed. "Our FBML tags are written not to run Javascript," Facebook asserted.

The failure to sanitize the content of third-party applications is one of several privacy and security gaffes that have threatened Facebook users over the past few years. In May they were poked by a cross-site scripting (XSS) flaw, and a separate security hole exposed the private pictures of Paris Hilton and who knows how many other users. Recently, security researchers have reported a worm that attacks users of Facebook and other social networking sites.

Tom Parker, manager of security consulting at Mu Dynamics, a security vendor, examined the proof of concept and validated Wachelka's claim that the vulnerability allowed the execution of arbitrary javascript.

Says Parker: "It's certainly a flaw that needs to be fixed." ®

Top 5 reasons to deploy VMware with Tegile

More from The Register

next story
'Regin': The 'New Stuxnet' spook-grade SOFTWARE WEAPON described
'A degree of technical competence rarely seen'
You really need to do some tech support for Aunty Agnes
Free anti-virus software, expires, stops updating and p0wns the world
You stupid BRICK! PCs running Avast AV can't handle Windows fixes
Fix issued, fingers pointed, forums in flames
Regin: The super-spyware the security industry has been silent about
NSA fingered as likely source of complex malware family
Privacy bods offer GOV SPY VICTIMS a FREE SPYWARE SNIFFER
Looks for gov malware that evades most antivirus
Patch NOW! Microsoft slings emergency bug fix at Windows admins
Vulnerability promotes lusers to domain overlords ... oops
HACKERS can DELETE SURVEILLANCE DVRS remotely – report
Hikvision devices wide open to hacking, claim securobods
prev story

Whitepapers

Why cloud backup?
Combining the latest advancements in disk-based backup with secure, integrated, cloud technologies offer organizations fast and assured recovery of their critical enterprise data.
Forging a new future with identity relationship management
Learn about ForgeRock's next generation IRM platform and how it is designed to empower CEOS's and enterprises to engage with consumers.
How to determine if cloud backup is right for your servers
Two key factors, technical feasibility and TCO economics, that backup and IT operations managers should consider when assessing cloud backup.
Reg Reader Research: SaaS based Email and Office Productivity Tools
Read this Reg reader report which provides advice and guidance for SMBs towards the use of SaaS based email and Office productivity tools.
Getting ahead of the compliance curve
Learn about new services that make it easy to discover and manage certificates across the enterprise and how to get ahead of the compliance curve.