A 2012 data breach that was thought to have exposed 6.5 million encrypted passwords for LinkedIn users instead likely impacted more than 117 million accounts, the company now says. In response, the business networking giant said today that it would once again force a password reset for individual users thought to be impacted in the expanded breach.

The 2012 breach was first exposed when a hacker posted a list of some 6.5 million unique passwords to a popular forum where members volunteer or can be hired to hack complex passwords. Forum members managed to crack some the passwords, and eventually noticed that an inordinate number of the passwords they were able to crack contained some variation of "linkedin" in them.

Time to change your LinkedIn password.

LinkedIn responded by forcing a password reset on all 6.5 million of the impacted accounts, but it stopped there. Earlier today, reports surfaced about a sales thread on an online cybercrime bazaar in which the seller offered to sell 117 million records stolen in the 2012 breach. In addition, the paid hacked data search engine LeakedSource claims to have a searchable copy of the 117 million record database (this service said it found my LinkedIn email address in the data cache, but it asked me to pay $US4 for a one-day trial membership in order to view the data; I declined).

Inexplicably, LinkedIn's response to the most recent breach is to repeat the mistake it made with original breach, by once again forcing a password reset for only a subset of its users.