Hackers Claim GMO Customer Data Exposure After $50 Million Ransom Demand

Hackers say they published customer information because GMO Internet Group did not pay a $50 million ransom demand, adding a potential data exposure claim to service disruptions at the Japanese company.

GMO's foreign exchange trading service has been suspended since Oct. 21, and the company has stopped accepting new subscriptions. The attack also breached every server operated by Onamae.com, GMO's domain and cloud services platform, potentially affecting the service's full user base.

Some customers had previously reported trades they did not authorize. Japan's finance minister 片山皋月 said five foreign exchange companies had reported affected customers, with no new reports of unauthorized trades as of Tuesday.

GMO has requested government help to block the attack's source and called for proactive cyberdefense measures. The reported effects span two customer-facing areas: forex trading access and the Onamae.com service environment.

GMO shares recorded their steepest fall since 2011 on Monday amid concern about worsening cyberattacks.