LinkedIn and eHarmony have contacted law enforcement authorities to help investigate the posting of a treasure trove of user passwords online. LinkedIn even brought in the FBI to help with the investigation of how millions of user passwords were leaked.
Earlier this week, the news circulated that a file with some 6.45 million SHA-1 hashed but unsalted passwords of LinkedIn users had been posted on a Russian Web forum. Other postings on the forum included hashes for 1.5 million passwords believed to belong to eHarmony users, though the dating site has not confirmed the number. In both cases, although the passwords were hashed, some have been decoded.
"We want to reiterate that we sincerely apologize for the inconvenience this has caused our members," blogged Vicente Silveira, director at LinkedIn. "From the moment we became aware of this issue, we have been working non-stop to investigate it¦(Wednesday) we learned that approximately 6.5 million hashed LinkedIn passwords were posted on a hacker site. Most of the passwords on the list appear to remain hashed and hard to decode, but unfortunately a small subset of the hashed passwords was decoded and published."
"To the best of our knowledge, no email logins associated with the passwords have been published, nor have we received any verified reports of unauthorized access to any members account as a result of this event," he added.
LinkedIn has invalidated the passwords believed to be at risk. As for eHarmony, the dating site said it has contacted affected users as well.
"We quickly secured the small percentage of accounts affected by this incident by disabling their passwords," blogged Becky Teraoka, of eHarmony corporate communications. "We sent an email to all affected members and provided them with specific instructions on how to change their password and tips on how to create a robust password. The email also included a direct phone number and live online chat access to our Customer Care team so we could personally address concerns and questions."
"While our investigation is ongoing, we have not found any indication that other information was accessed, nor have we received any reports of unauthorized logins to member accounts," she added.
Jim Walter, manager of the McAfee's Threat Intelligence Service, noted the exposure of the passwords is a good reminder to all Internet users of the importance of maintaining an "ever-changing and complex password."
"A secure passphrase may be the only thing standing between your personal data and those that wish to steal it," he said. "Password maintenance is simply an unavoidable best practice in today's digital world."
According to a June 6 analysis by Sophos, many of the hashed LinkedIn passwords have already been cracked.
"After removing duplicate hashes, SophosLabs has determined there are 5.8 million unique password hashes in the dump, of which 3.5 million have already been brute-forced," blogged Chester Wisniewski, a senior security advisor at Sophos. "That means over 60 percent of the stolen hashes are now publicly known. Of course, attackers already had a head start on the brute-force decryption, which means that all of the passwords may have now been recovered."
Silveira added that LinkedIn's current production database for account passwords is salted as well as hashed, but advised users to update their passwords on LinkedIn at least once every few months and not to use the same password for multiple sites or accounts.