Password management site LastPass has plugged a security hole in its website that created a means to extract the email addresses - though not the passwords - of enrolled users.
The cross-site scripting bug meant that logged-in users induced to visit a malicious site would disclose their email addresses and sites associated with a LastPass account, along with password reminders and a list of IP addresses used to access the site.
The bug was discovered by independent security researcher Mike Cardwell, who was unable to exploit the flaw to extract passwords.
LastPass - which boasts close to a million members - stores website login details in an encrypted container, safeguarded by a master password. Users log in to extract this information either directly via the website or by using a browser extension.
Cardwell reported the information disclosure bug to LastPass, which acted promptly in less than three hours to close the hole. In an advisory LastPass explains how it has improved security to prevent any repetition of the unfortunate incident, including ensuring browsers that support it (Chrome and Firefox 4) will be locked into secure SSL web requests when on the lastpass.com domain.
It's one of the more detailed explanations we've seen in many months and actually serves to give confidence that LastPass is prepared to grapple with security problems as they arise, rather than sweeping them under the carpet.
LastPass said a review of its logs indicated that no one beyond Cardwell had exploited the now fixed bug.
Nonetheless Cardwell remains concerned. "I believe this is ultimately a problem with their architecture and something which could easily happen again in future," he said. ®