Dear Niconico Users,
Thank you for using Niconico.
Since Thursday, December 28, 2017, we have detected multiple instances of unauthorized Niconico account logins.
Reports indicate that a set of user email addresses and passwords used in services outside of Niconico were obtained without authorization by an outside party. Furthermore, it appears that this party attempted to login to Niconico using the same email addresses and passwords.
*These attacks can be attributed to "list type account hacking."
Based on Niconico account registration data, it appears to that users living outside of Japan are primarily being targeted.
▼Possible activities as a result of unauthorized logins
Services within Niconico
・Use of Niconico Points
・Change in registered email address or password
・Posting of videos or comments
・Access to non-disclosed registered information (ex: gender, date of birth, etc.)
Services outside of Niconico
・Once an attacker successfully logins to Niconico, it may be possible for them to perform similar unauthorized logins for services outside of Niconico.
▼Steps to consider for protection
Please consider changing your Niconico account password if you use the same password for other services.
You can confirm your login history to Niconico from the link below.
https://account.nicovideo.jp/my/history/login
Please change your password immediately if you find any unfamiliar login entries from your login history.
As stated above, there is a possibility that the same method of attack may be used on services outside of Niconico.
Therefore, we ask that you please also consider changing your passwords for each service used outside of Niconico.
*For accounts where unauthorized logins have been determined, logins with original passwords have been disabled.
Affected users will be notified via their registered email address.
▼Change your password
Change your password from the following link.
https://account.nicovideo.jp/my/password
2 step authentication is an effective protective measure against list type account hacking.
See link below to set up 2 step authentication.
https://account.nicovideo.jp/my/security
▼Suspicious activity on your account
Please contact Niconico Customer Support if you experience suspicious activity on your account such as unfamiliar Niconico Point usage or change in your registered account information.