Feeds

Man knows when you're signed in to GMail, Twitter, Digg

Porn and warez logins ahoy!

Top 5 reasons to deploy VMware with Tegile

A UK-based web developer has figured out a simple way to tell if visitors to his site are logged in to Gmail, Facebook, Twitter, Digg and thousands of other websites.

One method developed by Mike Cardwell of Nottingham makes use of status codes returned by many sites, which differ depending on whether a user is logged in or not. By embedding a small piece of JavaScript that contains a link to one of the sites he's curious about, he can immediately tell if a visitor is logged in. The method works reliably for Twitter, Facebook and Digg when visitors are browsing with Firefox, Safari or Chrome.

It doesn't work when visitors are using Internet Explorer or Opera.

The exploit works by identifying the HTTP status code that's returned when the visitor's browser encounters the link in Cardwell's script. A 200 code, indicating the request was successfully fulfilled, indicates the person isn't logged in, while 404, 500 and other error codes indicate the opposite.

“This can be an awkward problem to avoid if you're developing a website,” Cardwell writes here. “Some of these requests could be stopped by doing referrer checks; reject all external referrers for content only accessible when logged in.

Detecting whether a visitor is logged in to Gmail requires a different script that generates a hidden image stored in Cardwell's mail folder that's configured to be viewable to everyone. Cardwell said he reported his finding to Google and was told it was “expected behaviour.”

“You may not care that I can tell you're logged into GMail, but would you care if I could tell you're logged into one or more porn or warez sites?” Cardwell asks rhetorically. “Perhaps http://oppressive-regime.example.org/ would like to collect a list of their users who are logged into http://controversial-website.example.com/?” ®

Top 5 reasons to deploy VMware with Tegile

More from The Register

next story
Webcam hacker pervs in MASS HOME INVASION
You thought you were all alone? Nope – change your password, says ICO
You really need to do some tech support for Aunty Agnes
Free anti-virus software, expires, stops updating and p0wns the world
USB coding anarchy: Consider all sticks licked
Thumb drive design ruled by almighty buck
Attack reveals 81 percent of Tor users but admins call for calm
Cisco Netflow a handy tool for cheapskate attackers
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
prev story

Whitepapers

Choosing cloud Backup services
Demystify how you can address your data protection needs in your small- to medium-sized business and select the best online backup service to meet your needs.
Getting started with customer-focused identity management
Learn why identity is a fundamental requirement to digital growth, and how without it there is no way to identify and engage customers in a meaningful way.
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.
Choosing a cloud hosting partner with confidence
Download Choosing a Cloud Hosting Provider with Confidence to learn more about cloud computing - the new opportunities and new security challenges.
Intelligent flash storage arrays
Tegile Intelligent Storage Arrays with IntelliFlash helps IT boost storage utilization and effciency while delivering unmatched storage savings and performance.