Yahoo Japan says 22 million user IDs may have been stolen

Japan's biggest Web portal said its ID servers were hacked, but no passwords or private info were leaked

Yahoo Japan, the country's largest Web portal, said up to 22 million user IDs may have been leaked during a hack that was discovered last week.

The company emphasized that the IDs are already public information, and no passwords or other private data were affected. Yahoo Japan IDs are used along with password to log in to the site, and are often displayed when users leave comments or use its shopping or auction services.

Yahoo Japan said it discovered illicit access to its ID servers on Thursday evening, and upon further investigation found a file with 22 million user IDs on it. The company said it wasn't sure if the file had been transferred outside of the company, but couldn't deny the possibility.

The website posted warnings of the possible breach on its login pages, and offered a service for users to check if their IDs were among those that were possibly leaked. Yahoo Japan said last year it had over 24 million active user IDs.

Yahoo Japan does not allow users to change their IDs without creating an entirely new account, which means losing access to existing mail and other data. The company does allow creation of a secondary user ID it calls a "Secret ID," which is used solely for logging in and not meant to be shared publicly.

The company introduced the Secret ID feature as part of a security upgrade after a security breach last month. Yahoo Japan said it had discovered a malicious program on company servers that had extracted user data for 1.27 million users, but the program was stopped before it leaked any of the data outside of the company.

Yahoo Japan is the country's most-visited Web property, according to Web data provider Alexa, and the 15th most visited site globally. It is majority owned by Softbank, which also runs one of the country's largest mobile phone operators and a large broadband service. Yahoo holds a 35 percent stake in the portal.

Join the CSO newsletter!

Error: Please check your email address.

Tags Internet-based applications and servicessecurityYahoo Japandata breachinternetsearch engines

More about SoftbankYahoo

Show Comments

Featured Whitepapers

Editor's Recommendations

Solution Centres

Stories by Jay Alabaster

Latest Videos

  • 150x50

    CSO Webinar: The Human Factor - Your people are your biggest security weakness

    ​Speakers: David Lacey, Researcher and former CISO Royal Mail David Turner - Global Risk Management Expert Mark Guntrip - Group Manager, Email Protection, Proofpoint

    Play Video

  • 150x50

    CSO Webinar: Current ransomware defences are failing – but machine learning can drive a more proactive solution

    Speakers • Ty Miller, Director, Threat Intelligence • Mark Gregory, Leader, Network Engineering Research Group, RMIT • Jeff Lanza, Retired FBI Agent (USA) • Andy Solterbeck, VP Asia Pacific, Cylance • David Braue, CSO MC/Moderator What to expect: ​Hear from industry experts on the local and global ransomware threat landscape. Explore a new approach to dealing with ransomware using machine-learning techniques and by thinking about the problem in a fundamentally different way. Apply techniques for gathering insight into ransomware behaviour and find out what elements must go into a truly effective ransomware defence. Get a first-hand look at how ransomware actually works in practice, and how machine-learning techniques can pick up on its activities long before your employees do.

    Play Video

  • 150x50

    CSO Webinar: Get real about metadata to avoid a false sense of security

    Speakers: • Anthony Caruana – CSO MC and moderator • Ian Farquhar, Worldwide Virtual Security Team Lead, Gigamon • John Lindsay, Former CTO, iiNet • Skeeve Stevens, Futurist, Future Sumo • David Vaile - Vice chair of APF, Co-Convenor of the Cyberspace Law And Policy Community, UNSW Law Faculty This webinar covers: - A 101 on metadata - what it is and how to use it - Insight into a typical attack, what happens and what we would find when looking into the metadata - How to collect metadata, use this to detect attacks and get greater insight into how you can use this to protect your organisation - Learn how much raw data and metadata to retain and how long for - Get a reality check on how you're using your metadata and if this is enough to secure your organisation

    Play Video

  • 150x50

    CSO Webinar: How banking trojans work and how you can stop them

    CSO Webinar: How banking trojans work and how you can stop them Featuring: • John Baird, Director of Global Technology Production, Deutsche Bank • Samantha Macleod, GM Cyber Security, ME Bank • Sherrod DeGrippo, Director of Emerging Threats, Proofpoint (USA)

    Play Video

  • 150x50

    IDG Live Webinar:The right collaboration strategy will help your business take flight

    Speakers - Mike Harris, Engineering Services Manager, Jetstar - Christopher Johnson, IT Director APAC, 20th Century Fox - Brent Maxwell, Director of Information Systems, THE ICONIC - IDG MC/Moderator Anthony Caruana

    Play Video

More videos

Blog Posts