Feeds

Facebook takes the Captcha rap

Stop the word verification madness

Seven Steps to Software Security

From time to time we capture word verification silliness for posterity. It's been a while, but we've got another for you, this time from Facebook - and this time it ain't so silly.

The text reads: "rape now". It was displayed next to the picture of a female work colleague our tipster (a Reg reader, of course) was adding to his list of Facebook friends?

Screenshot from Facebook captcha that reads: "rape now"

While Facebook calls such scripts "security checks," the rest of the world knows them as captchas, short for completely automated public Turing Test to tell computers and humans apart. The point is to display an image that's not easily recognizable to a computer to ensure a real person is on the other end of a transaction.

The offending captcha was generated by ReCaptcha, a project sponsored by Carnegie Mellon University researchers working on a novel way of digitizing old books. Optical character recognition can stumble on as much as 30 per cent of the words it encounters. ReCaptcha displays them to users of Facebook and other sites. When they type in the corresponding text, the mystery is solved.

"Although there is very heavy filtering against offensive CAPTCHAs (we have over 1000 words in our list of offensive terms), in very rare cases, inappropriate words can be shown," Luis von Ahn, a professor working on the project explained in an email. "We work very hard to keep such words out of the system, but in general it is impossible to guarantee that nothing offensive will ever be displayed."

He said ReCaptcha displays about 30 million images every day and generally gets fewer than one complaint each month.

We knew there was something strange about the words being displayed on Facebook's security check. While cycling through we got combinations that included "mutton synagogue," Toledo playmates" and "wiped president."

Von Ahn says this isn't the first cockup to affect a captcha, and pointed us to several examples, two of which we include below.

Screenshot of Google Adwords captcha that reads: "pness"

Screenshot of Google captcha that reads: "nodick"

We see his point. ®

Mobile application security vulnerability report

More from The Register

next story
Yorkshire cops fail to grasp principle behind BT Fon Wi-Fi network
'Prevent people that are passing by to hook up to your network', pleads plod
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
Attackers raid SWISS BANKS with DNS and malware bombs
'Retefe' trojan uses clever spin on old attacks to grant total control of bank accounts
Manic malware Mayhem spreads through Linux, FreeBSD web servers
And how Google could cripple infection rate in a second
Mozilla fixes CRITICAL security holes in Firefox, urges v31 upgrade
Misc memory hazards 'could be exploited' - and guess what, one's a Javascript vuln
Don't look, Snowden: Security biz chases Tails with zero-day flaws alert
Exodus vows not to sell secrets of whistleblower's favorite OS
prev story

Whitepapers

Designing a Defense for Mobile Applications
Learn about the various considerations for defending mobile applications - from the application architecture itself to the myriad testing technologies.
How modern custom applications can spur business growth
Learn how to create, deploy and manage custom applications without consuming or expanding the need for scarce, expensive IT resources.
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.
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.