TweetDeck XSS flap: Miscreants flash their naughty bits at users

Updated Twitter aficionados are being warned to log out of Twitter client TweetDeck and revoke its access to their accounts after an apparent cross-site scripting vulnerability was discovered.

Multiple users – including El Reg's HQ in London, England – reported on Wednesday that they had seen a suspicious pop-up within Tweetdeck that said “XSS in Tweetdeck”.

This exploit was able to execute arbitrary JavaScript in the user's browser – this is very bad as it means a hacker could potentially exploit the flaw to hijack an account, redirect the browser page to somewhere nasty, unleash eldritch digital horrors (and, yes, open pop-ups).

Users should log out of Tweetdeck and revoke the app's access to their accounts from within Twitter (found under Settings > Apps) until the flaw has been fully dealt with.

<script>alert("XSS in tweetdeck");</script>♥

— freakyclown (@__Freakyclown__) June 11, 2014

There's evidence that the flaw was invoked by simply enclosing text in a Tweet in tags – a flaw that last cropped up in 2011 before being papered over.

Twitter's press office had not responded to a request by El Reg for more information at the time of writing.

A security issue that affected TweetDeck this morning has been fixed. Please log out of TweetDeck and log back in to fully apply the fix.

— TweetDeck (@TweetDeck) June 11, 2014

At the time of writing, the Twitter account for TweetDeck stated that the vulnerability had been fixed, but reports are still flooding into Vulture HQ of the flaw running in the wild. ®

Updated to add

Some enterprising security research has figured out how to craft the XSS vuln into a self-propagating one by forcing Twitter clients to retweet it.

Oh dear. That Tweetdeck XSS vulnerability is RT-ing stuff... its just hit @BBCBreaking! pic.twitter.com/8siffmsFxi

— Matt Navarra (@MattNavarraUK) June 11, 2014

That particular tweet has now been retweeted almost 40,000 times and, just a few minutes ago, propagated onto the BBC's Breaking News account, which has over 10 million followers. Gulp!

Updated (again) to add

We've verified our security fix and have turned TweetDeck services back on for all users. Sorry for any inconvenience.

— TweetDeck (@TweetDeck) June 11, 2014

After pulling TweetDeck services down, Twitter has verified its security fix and brought the tech back online, promising that the vulnerability has been fixed. ®

Vulnnote

This is one of the various messages that appeared on Vulture Central's screens earlier:

For everyone asking why it's important to get off Tweetdeck right now, this is why. pic.twitter.com/lK3J7K0vwT (via @addelindh)

— The Register (@TheRegister) June 11, 2014