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Tentac Ransomware Attack

tentac.co.jpRansomed

thegentlemenGroup

JapanCountry

Sep 15, 2026Discovered

Overview

View group profile

Domain

tentac.co.jp

Country

Japan

Discovered

4 days ago

Attack date

Sep 15, 2026

Confidence

90%

Severity

Medium

Status

Claimed

Threat group

thegentlemen

Total victims

866

First seen

Sep 2025

Last seen

Sep 2026

Group status

active

Sophistication

Impact score

Threat level

4.3/10

Aggressiveness10/10

Lethality0/10

Criticality2.7/10

Status breakdown

Data Leaked0.5%4

Negotiating0.2%2

Claimed

this victim

99.3%860

Targeted sectors

Education Energy & Utilities Financial Services Government & Defense Healthcare Hospitality Manufacturing Other Professional Services Retail & E-Commerce Technology Transportation

Victim's position within group

Country

Japan

Frequently targeted country

Other victims

View all (866)

Same group · thegentlemen

Tentac
Japan
Claimed
TENTAC Co., Ltd
Japan
Claimed
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Germany
Claimed
Vittoria Assicurazioni
Italy
Claimed
TMI Tecnicas Mecanicas Ilerdenses
Spain
Claimed
Sarku Japan
Japan
Claimed

Group activity

Monthly attacks · thegentlemen

866

total · avg 66.6/mo