Researchers have released a Firefox extension that demonstrates the risks of using Google search services on Wi-Fi hotspots and other unsecured networks: With just a few clicks, attackers can view large chunks of your intimate browsing history, including websites you've already visited.
The proof-of-concept addon is an extension of Firesheep, a Firefox extension released in October that streamlined the process of hijacking private accounts on Facebook, Twitter, and other websites. Neither plug-in exploits newly discovered vulnerabilities. Rather, their significance lies in raising new awareness about an architectural weakness that has plagued the web since its beginning.
The newly released addon automatically intercepts SID, or session ID, cookies that Google uses to personalize search results based on an individual's previous searches. The file is transmitted each time a Google.com website is accessed while a user is logged into her account and can be used to retrieve on average 40 percent of her click history. The cookie is sent in plaintext – in some cases even when a user has deployed services such as HTTPS-Everywhere to force encrypted connections – making it easy to intercept on unsecured networks.
“We extended Firesheep to implement our information leakage attack,” researchers Vincent Toubiana and Vincent Verdot of the Alcatel-Lucent Bell Labs wrote in a recently released paper (PDF). “As a result, when a Google SID cookie is captured, the account name appears in the Firesheep sidebar. Double clicking on it starts the attack; double clicking again displays the retrieved list of visited links.”
A Google spokesman sent a statement that read in part:
We consider the concerns raised by these researchers to be fairly academic in nature and not a significant risk to users. Google Web History and our Web Search suggestion service are served over HTTPS, and we have encrypted the back-end server requests associated with the suggestion service as well. We look forward to providing more support for SSL technologies across our product offerings in the future, including changes that will specifically protect hijacked cookies from being used to access search data.
The researchers said users can protect themselves by logging out of their Google accounts while connecting over networks they don't trust. Another countermeasure is to disable Google's “visited” and “social” search filters. ®