Original URL: https://www.theregister.com/2013/05/20/yahoo_japan_user_id_breach/

Yahoo! Japan says 22 MEELLION User IDs may have been nabbed

Suspected breach didn't nab passwords but resets nonetheless recommended

By Phil Muncaster

Posted in Security, 20th May 2013 04:07 GMT

Yahoo! Japan has told its 200 million customers to change their passwords after revealing that 22 million user IDs may have been exposed in a suspected intrusion last week.

The attack was detected at around 9:00 PM local time on Thursday night, with the internet giant apparently cutting access while it checked what had happened.

Reports suggest it discovered an attempt to steal User IDs, with a file containing 22 million potentially exposed.

“We don’t know if the file was leaked or not, but we can’t deny the possibility, given the volume of traffic between our server and external terminals”, Yahoo! Japan said in a statement sent to AFP.

Although the data which may have been compromised apparently doesn’t include passwords and the kind of user data needed to reset passwords, the firm is taking no chances.

Hackers also tried to breach Yahoo! Japan last month in a similar raid on user data, although their motives remain unclear.

Yahoo! Japan is a joint venture between the internet pioneer and Japanese mobile and broadband operator SoftBank, which remains one of the US giant’s few remaining success stories.

In the first quarter of 2013, it was Yahoo!’s Japan JV – in which it has a 33 per cent stake – as well as its 20 per cent investment in China’s Alibaba, which helped the firm to record a 36 per cent year-on-year increase in net income to $390 million (£253.9m). ®