Cyber Threat Intelligence
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Ransomware Victim

Yaomasa

Ransomware attack by Ailock · Disclosed August 13, 2026 · 🇯🇵 Japan

yaomasa.com

Date Disclosed
Aug 13, 2026
2026
Threat Group
Ailock
51 total victims
Country
🇯🇵 Japan
Industry
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ThreatAI Analysis

Compiled from this incident record and the threat intelligence profile for Ailock. Figures and technique mappings are quoted from the source data, not inferred.

Ailock listed Yaomasa on its dark web leak site on 13 August 2026; the Japanese supermarket chain offers fresh foods and daily necessities along with cultural franchise stores.

About Yaomasa

Yaomasa is a Japanese supermarket chain founded in 1919 that offers fresh foods, general groceries, and daily necessities, while also operating TSUTAYA and BOOKOFF franchise stores as part of its cultural division.

Source record: ransomware.live

About the Ailock group

AiLock is a ransomware operation that emerged in early 2025, marketing itself as AI-assisted ransomware using a hybrid ChaCha20/NTRUEncrypt encryption scheme and double-extortion tactics, actively recruiting affiliates and threatening regulatory reporting if ransoms are unpaid. Ailock has listed 47 victims since April 2015.

Incident Analysis

Yaomasa was targeted by Ailock ransomware, one of the most active ransomware groups in our database with 51 confirmed victims globally. The attack was disclosed on August 13, 2026, when Yaomasa appeared on the group's dark web leak site.

Yaomasa is based in Japan . Japan ranks #11 globally for ransomware attacks, with 266 victims in our database.

Ailock typically employs a double extortion model: first exfiltrating sensitive data from the victim's systems, then deploying ransomware to encrypt files. Victims face two simultaneous threats — paying to restore access and paying to prevent publication of stolen data. The group's leak site publishes victim names and exfiltrated data as leverage.

Data source: This incident record is sourced from public ransomware group leak site disclosures aggregated via the ransomware.live API. Disclosure date reflects when the victim was published on the leak site, which may differ from the initial date of compromise. This platform does not publish or link to stolen data. Last data update: Sep 5, 2026 18:00 UTC.

Frequently Asked Questions

Was Yaomasa attacked by ransomware?

Yes. Yaomasa was listed as a victim of the Ailock ransomware group on August 13, 2026. The organisation is based in Japan. The disclosure appeared on the group's dark web leak site.

Which ransomware group attacked Yaomasa?

Yaomasa was attacked by Ailock ransomware. Ailock is one of the most active ransomware groups, having claimed 51 victims globally. The group typically employs a double-extortion model: encrypting the victim's files and threatening to publish stolen data.

When did the Yaomasa ransomware attack occur?

The ransomware attack on Yaomasa was disclosed on August 13, 2026. This date reflects when the victim was published on the threat group's leak site, which may differ from the actual date of initial compromise.

What data was stolen in the Yaomasa ransomware attack?

The specific data stolen from Yaomasa has not been independently verified by this platform. Ransomware groups typically exfiltrate data before encrypting systems and use the threat of publication to pressure victims. Sensitive business data was likely targeted.

How can organisations protect against Ailock attacks?

To defend against Ailock and similar threat actors, organisations should: maintain regular offline backups tested for restoration; implement network segmentation to limit lateral movement; deploy multi-factor authentication on all remote access; use endpoint detection and response (EDR) tools; conduct regular phishing and security awareness training; and monitor threat intelligence feeds for indicators of compromise (IOCs) associated with active groups.