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The Yomiuri Shimbun Confiscated smartphones and PCs are seen at the Otsuka Police Station of the Metropolitan Police Department on Thursday.
The Yomiuri Shimbun
2:00 JST, February 28, 2025
Three junior and senior high school students have been arrested on suspicion of illegally logging into Rakuten Mobile’s system with a self-made computer program and obtaining mobile phone accounts, the Metropolitan Police Department said Thursday.
Aged 14 to 16, the students are suspected of attempting to use 3.3 billion IDs and passwords they purchased via social media to log in and obtain mobile service accounts that they could resell. They allegedly managed to log in with about 220,000 IDs and passwords, investigative sources said.
In creating the program, the students used Chat GPT interactive generative AI to improve their efficiency and processing speed. This is an extremely rare case of large-scale illegal access by minors who used generative AI in an illicit fashion.
Police have arrested a 15-year-old junior high school student from Maibara, Shiga Prefecture, a 16-year-old high school student from Ogaki, Gifu Prefecture, and a 14-year-old junior high school student from Tachikawa, Tokyo.
One was quoted as telling investigators, “We’ve obtained more than 1,000 mobile phone accounts since December 2023.”
According to investigative sources, the three became acquainted via online games and allegedly purchased a set of 3.3 billion IDs and passwords from a person they met through Telegram, a communication app offering a high degree of confidentiality.
The police searched the three students’ houses from June to September last year and analyzed their PCs and smartphones. They found about 3.3 billion IDs and passwords, as well as traces of their log-in histories for the Rakuten Mobile system with about 220,000 IDs and passwords.
Their self-made program is sophisticated, automatically entering IDs and passwords. Once those were authenticated, the program allowed them to log into Rakuten Mobile’s system and obtain mobile service accounts.
It was created mainly by the high school student in Gifu, who taught himself how to do it. All three used the program.
The students are accused of illegally reselling the mobile service accounts to several people via Telegram. Police believe that they obtained about ¥7.5 million worth of cryptocurrency.
They were arrested from Feb. 3 through Tuesday on suspicion of illegally logging in with IDs and passwords belonging to 11 people between May and August last year and obtaining 105 eSIM (embedded SIM) accounts.
“I saw a post on SNS that bragged about crime techniques, and wanted to get attention by posting even more sophisticated techniques,” the junior high school student in Shiga was quoted as saying to investigators.
Rakuten Mobile allows a maximum of 15 mobile service accounts to be created with a single Rakuten ID. The three students are believed to have obtained multiple accounts with each single illicit login.
If proven, the charges would constitute violations of the Law on Prohibition of Unauthorized Computer Access and computer fraud.
