"The compromised information was provided by writers who had joined Associated Content prior to May 2010, when it was acquired by Yahoo!," the company said in a statement, and added that the file in question was a standalone file that was not used to grant access to Yahoo! systems and services.
Users who have joined Associated Content prior to May 2010 using their Yahoo! email address are urged to log in to their Yahoo! account where they will be asked to answer a series of authentication questions to change and validate their credentials.
Yahoo! says that they have also deployed additional security measures for affected Yahoo! users, enhanced their underlying security controls and are in the process of notifying affected users.
In the meantime, the group responsible for the hack of the official forum site of technology company NVIDIA has also dumped some user 800 records exfiltrated during the breach.
The hacker group, which calls itself "The Apollo Project", claims that they also managed to compromise shop.nvidia.com, but offered no proof of it. They also announced that the rest of the record will be duped at a later stage.
Reading our newsletter every Monday will keep you up-to-date with security news.
Receive a daily digest of the latest security news.