Internet stats clearinghouse Netcraft has released a new tool aimed at letting consumers know when the sites they visit might have been compromised by the Heartbleed encryption bug.
What makes the new version of the Netcraft browser extension different is that it queries historical data to see whether a site might have been vulnerable prior to the Heartbleed disclosure, even if it has since updated its OpenSSL libraries.
In addition to upgrading their SSL code, sites that were previously vulnerable should also replace their SSL certificates. That's because their old certificates could have been compromised during the time they were running the flawed OpenSSL libraries, potentially allowing attackers to impersonate the sites in phishing attacks and other scams.
If the Netcraft extension determines that a site was vulnerable before news of Heartbleed broke, it checks the date on the site's SSL certificate to make sure it has been recently replaced. If it hasn't, the extension displays an alert.
You might be surprised at some of the high-profile sites the tool still counts as suspicious, too. According to Netcraft's blog post announcing the new tool, social site LinkedIn has already replaced its SSL certificate, for example, but international shipper FedEx has not.
"Fedex's website is hosted by Akamai, a popular Content Distribution Network, which was potentially vulnerable to Heartbleed," Netcraft's Paul Mutton wrote. "Akamai is in the process of rotating its customers' SSL certificates and stated that 'some require extra validation with the certificate authorities and may take longer'."
Netcraft's updated browser extension is available as a free download for Firefox 1.0 and later; Chrome 26 and later on Windows, OS X, and Linux; and for Opera 15 and later on OS X and Windows. Versions for other browsers aren't available, unfortunately, which means users of Internet Explorer and Safari are left in the dark. ®