Data leak shows rapprochement between lIokyo and Seoul remains fragile

Breach involves Japan’s messaging app Line and South Korea’s search engine Naver

- Walter Sim

TOKYO A data breach involving the parent companies of Japan's most popular messaging app Line and South Korea's most used search engine Naver threatens to reverse a thaw in relations between the two East Asian neighbours.

A spate of leaks of over 500,000 user records at LY Corp, which runs Line and Yahoo Japan, from November 2023 to February 2024, had prompted Japan's Ministry of Internal Affairs and Communications (MIC) to issue "administrative guidance".

This is as per protocol, and the ministry has issued similar or stronger advisories over breaches involving other companies.

But the data breach involving mainly user records of Line which is also popular in Taiwan, Thailand and Indonesia - has an added diplomatic dimension, having been traced to security lapses in South Korea.

LY's majority stakeholder is A Holdings, a 50-50 joint venture between Japan's SoftBank Group and South Korea's Naver Corp.

LY has a stake in PayPay, one of Japan's top mobile payment services. LY's services are used by 320 million people at home and abroad, according to company data.

Line is used not just for private chats in Japan, but also by companies and public entities.

Line shares its system authentication infrastructure with Naver, which meant Line user data could be accessed from South Korea.

Among other things, Tokyo blamed the cyberleaks on Line's "strong dependence on Naver in terms of systems and network configuration", as it urged a review of how data is managed to prevent unauthorised access.

"This relationship has also made it difficult for (LY) to demand appropriate safety measures from Naver and to implement proper management of outsourced parties," the MIC added, suggesting steps such as a "review of capital relationship".