Was Yaomasa hit by ransomware?

Yaomasa was listed by the AiLock ransomware operation (Japan), and stolen data was published on the group's leak site. Darkfield tracks this disclosure with the original leak post, screenshot and group context.

Who is the AiLock ransomware group?

AiLock is a ransomware operator tracked by Darkfield. See the full operator dossier for its known victims, sectors targeted, IOCs and leak-site infrastructure.

What data was leaked in the Yaomasa breach?

AiLock published data attributed to Yaomasa. Darkfield captured the leak post and a screenshot of the listing.

Ransomware victim disclosure

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Yaomasa

Claimed by AiLock · listed 5 days ago

Age

since listed · data leaked

Status timeline

ListedAug 13, 2026
Data leakeddate unknown

At a glance

Group: AiLock
Status: Data leaked
Country: Japan
Listed on leak site: Aug 13, 2026

About the victim

AI dossier — public-source company profile

Yaomasa is a Japanese supermarket chain founded in 1919 that operates retail stores offering fresh foods, general groceries, and daily necessities. The company also operates TSUTAYA and BOOKOFF franchise stores as part of its cultural division.

Industry: Retail & Supermarket Chains
Founded: 1919

Attack summary

Severity: medium — Data has been published by the threat actor, indicating confirmed exfiltration. However, the absence of specific data inventory details, proof files description, or known sensitive data types (PII at scale, financial records, etc.) prevents classification as 'high' or 'critical'. A retail chain's operational data exposure is of moderate concern.

AiLock claims to have compromised Yaomasa, with data published according to the disclosed status, though specific details of what was exfiltrated or encrypted are not provided in the available leak post excerpt.

medium

What the group claims

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.

Sources

Victim siteyaomasa.com

Source

Indexed 5 days ago

This page surfaces a public ransomware disclosure indexed by Darkfield. Original posts come from the operator's own leak site; we cross-check against ransomware.live, RansomLook and RansomWatch where applicable. Share this URL freely.

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Disclosure context

About AiLock

AiLock is an emerging ransomware group first observed in March 2026 with a primarily financial motivation, having targeted at least 24 known victims across multiple sectors. The group's origin and affiliations remain largely undocumented by major threat intelligence organizations, though their targeting patterns suggest a broad operational scope spanning the United States, Canada, Great Britain, China, and Germany. Based on publicly available information from security researchers, AiLock appears to focus on technology companies, consumer services, manufacturing, and public sector entities, though specific attack methodologies, initial access vectors, and encryption techniques have not been extensively documented by CISA, FBI, or major security firms. The group's relatively recent emergence and limited public documentation suggest they may be a smaller operation or newly formed entity, with no notable major campaigns or high-profile ransoms publicly reported by established threat intelligence sources. Given the March 2026 first observation date and lack of subsequent major public reporting, AiLock's current operational status and capabilities remain largely undetermined by mainstream cybersecurity organizations. The group has been linked to 49 public disclosures across our corpus. First observed on a leak site on March 3, 2026; most recent post August 13, 2026. The operation is currently active.

Timeline of this disclosure

August 13, 2026Yaomasa listed by AiLockon the group's public leak site

Other recent disclosures by AiLock

AiLock has been linked to 49 public victims on Darkfield. A sample of the most recent:

See the full AiLock dossier →

Sector and geography

Geographically, Yaomasa is reported in Japan, a country with 89 ransomware disclosures in our corpus.

If your organisation is affected

A listing by AiLock means Yaomasa appeared on a ransomware extortion site and data attributed to it has been published. If this is your organisation, or a supplier you depend on, the priority is to confirm the intrusion and contain it before the window to act closes.

Engage your incident-response team and preserve forensic evidence before remediating — do not wipe affected systems first.
Force a password reset and revoke active sessions for exposed accounts; rotate any credentials, API keys or certificates that may have been in the stolen data.
Assess regulatory notification duties (GDPR, NIS2, sector regulators) — many carry a 72-hour reporting clock from awareness.
Report the incident to your national CERT, JPCERT/CC (Japan), as required for your jurisdiction.
Monitor for the data appearing on AiLock's leak site and across paste and breach channels, and brief downstream partners who may be exposed through you.

How we know this. Darkfield monitors public ransomware leak sites continuously, archiving every new disclosure and the data later released against the victim. Each entry on this page is sourced from the operator's own publication and cross-checked against complementary OSINT feeds (RansomLook, ransomware.live, RansomWatch). We do not collect or host stolen data — only the metadata, timestamps and screenshots needed to make the public disclosure searchable and accountable. Records here are corrected when the original post is edited, retracted, or merged with another disclosure.