The BlackCat/ALPHV ransomware gang has added Seiko to its extortion site, claiming responsibility for a cyberattack disclosed by the Japanese firm earlier this month.

Seiko is one of the world’s largest and most historic watchmakers, with roughly 12,000 employees and an annual revenue that surpasses $1.6 billion.

On August 10th, 2023, the company published a notice of a data breach informing that an unauthorized third-party gained access to at least a part of its IT infrastructure and accessed or exfiltrated data.

“It appears that [on July 28, 2023] some as-yet-unidentified party or parties gained unauthorized access to at least one of our servers,” reads Seiko’s announcement.

“Subsequently, on August 2nd, we commissioned a team of external cybersecurity experts to investigate and assess the situation.”

“As a result, we are now reasonably certain that there was a breach and that some information stored by our Company and/or our Group companies may have been compromised.”

Seiko apologized to the potentially impacted customers and business partners and urged them to be vigilant against email or other communication attempts potentially impersonating Seiko.

BlackCat assuming responsibility

Today, the BlackCat ransomware group claimed to be behind the attack on Seiko, posting samples of data that they claim to have stolen during the attack.

In the listing, the threat actors mock Seiko’s IT security and leak what appear to be production plans, employee passport scans, new model release plans, and specialized lab test results.

Most worryingly, the threat actors have leaked samples of what they claim are confidential technical schematics and Seiko watch designs.

This indicates that BlackCat very likely possesses drawings that showcase Seiko internals, including patented technology, which would be damaging to publish and expose to competitors and imitators.

BlackCat is one of the most advanced and notorious ransomware gangs actively targeting the enterprise, constantly evolving its extortion tactics.

For example, the group was the first to use a clearweb website dedicated to leaking data for a particular victim and, more recently, created a data leak API, allowing for easier distribution of stolen data.

BleepingComputer has contacted Seiko for additional comments on the threat actor’s claims, but we have not received a response by publication time.