Tokyo, Oct. 31 (Jiji Press)--Users of the foreign exchange margin trading service affected by a cyberattack on GMO Internet Inc. have called on the company to explain how millions of yen in assets were lost virtually overnight.

In the cyberattack, perpetrators gained unauthorized access to GMO Internet servers used to provide the Onamae.com Desktop Cloud margin trading service.

A company worker in her 20s in Aichi Prefecture, central Japan, discovered that she had fallen victim to the cyberattack on the morning of Oct. 22. In unauthorized transactions conducted around 5 a.m., some 50 trades were executed in roughly 3 minutes, causing her to lose 4.3 million yen, or almost all the assets in her account.

"I trusted the service because it was operated by a major company," she said.

"I now feel uneasy about all kinds of services connected to the internet," she continued. "I want (the company) to clarify what happened."

[Copyright The Jiji Press, Ltd.]