Executive Summary
IDC Frontier, a SoftBank subsidiary, says a ransomware attack that began at about 3:40 a.m. local time on 7 October stopped virtual servers across four zones of its IDCF Cloud platform in East Japan Region 1. Data held in those zones cannot be extracted or restored. It counts 495 affected corporate and municipal customers. A day later the service was still down, with no recovery date.
Cloud ransomware recovery here rests on what customers hold themselves. IDC Frontier says the only reasonable path is a copy kept outside its infrastructure. MLex reported that at least one prefecture could not reach its own backup once the platform went dark. A snapshot inside the provider’s account is not a copy when the provider is the thing that failed.
The provider has published three bulletins in two days. A third party used ransomware, the affected zones went dark, and the data in them is not coming back through anything IDC Frontier controls.
IDCF Cloud runs public websites for Ibaraki Prefecture and its police force, the hardware behind Six Apart’s Movable Type cloud service, and the logistics system Nissui runs across 17 sites. When IDC Frontier cut the network, all of it stopped at once.

A console stopped in regions nobody touched
The company shut the customer management console in every region, not only the affected one, because that console is a single administrative surface for the whole estate. NHK World reported the outage reached customers outside the incident. A compromise in one region became a nationwide loss of control over systems no attacker had reached. It was the right call, and it still hurt.
One prefecture could not reach its own backup
The Asahi Shimbun reported the prefectural outages and the halted shipments at Nissui Logistics. The Mainichi reported that images claiming to come from the attacker were circulating and that IDC Frontier was still checking whether they were genuine. The attacker’s claims about data volume remain unverified.
Three questions worth answering this week. Where does your backup live, and under whose credentials? Can you restore it while your provider’s console is offline? And when did you last prove that answer instead of assuming it?
Related reading. When a hyperscaler told customers two regions were not coming back.
Sources. IDC Frontier incident bulletins, NHK World, The Asahi Shimbun, The Mainichi and MLex.
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[…] pattern is not new. When a single provider’s region failed wholesale in Japan, IDCF Cloud told 495 customers to restore from their own backups, because the backups were inside the same region. The same lesson arrived from a different […]