Unmasking The Gentlemen Ransomware: Tactics, Techniques, and Procedures Revealed
Summary:
The Gentlemen ransomware group has surfaced as a sophisticated and well-resourced threat actor, conducting campaigns across at least 17 countries and multiple industries, with a strong focus on manufacturing, construction, healthcare, and insurance. First observed in August 2025, the group employed a broad range of advanced techniques, including legitimate driver exploitation, Group Policy manipulation, privileged account compromise, and the deployment of custom anti-AV utilities designed to disable specific security vendors. Their operations were marked by adaptability, with tools modified mid-campaign to better evade defenses, and detailed reconnaissance carried out to map Active Directory structures and privilege groups. Living-off-the-land techniques such as PsExec, PowerRun.exe, and registry modifications facilitated lateral movement, while persistence was maintained through AnyDesk installations and GPO abuse. Data staging and exfiltration were methodically executed using tools like Nmap, PuTTY, and WinSCP. Ultimately, ransomware payloads were distributed domain-wide via NETLOGON shares, aggressively terminating services, disabling Windows Defender, deleting forensic evidence, and encrypting files with password-protected executables before dropping ransom notes labeled README-GENTLEMEN.txt. The campaign reflects a shift away from broad, opportunistic ransomware toward highly tailored, environment-specific attacks.
Security Officer Comments:
The Gentlemen’s tactics underscore the rapid evolution of ransomware from commodity malware into targeted operations resembling advanced persistent threats. By developing custom tools against individual endpoint security vendors and combining them with the abuse of legitimate drivers and administrative utilities, the group demonstrates both high technical skill and significant financial backing. Their willingness to adapt in real time during campaigns, along with the use of encrypted exfiltration and persistent access channels, indicates operational maturity and a deliberate focus on ensuring success even in hardened environments.
Suggested Corrections:
Adopt Zero Trust principles: Eliminate direct RDP exposure to the internet, enforce MFA for all administrative accounts, and segment IT management tools from production systems to reduce the blast radius of a compromise.
Harden privileged accounts: Implement time-based access controls with automatic de-escalation, monitor for anomalous domain controller activity, and alert on bulk Active Directory queries or group membership changes.
Strengthen endpoint defenses: Enable tamper protection, agent self-protection, and application control on endpoint security solutions to prevent attackers from disabling defenses. Block execution of tools from temporary or download directories, and monitor for suspicious service termination attempts.
Control driver abuse: Enforce driver signature verification and monitor for attempts to load vulnerable or unsigned drivers, as The Gentlemen exploited legitimate drivers for defense evasion.
Enhance detection and response: Deploy behavioral detection for privilege escalation, credential dumping, and lateral movement activities. Use deception technologies on sensitive shares to catch reconnaissance early.
Secure exfiltration paths: Monitor encrypted outbound traffic for anomalies, paying special attention to file transfer tools like WinSCP or PuTTY, and restrict unauthorized remote access utilities such as AnyDesk.
Patch and monitor perimeter devices: Apply virtual patching and updates for VPN appliances, firewalls, and other internet-facing services. Continuously monitor for suspicious activity against these high-value entry points.
Link(s):
https://www.trendmicro.com/en_us/research/25/i/unmasking-the-gentlemen-ransomware.html
The Gentlemen ransomware group has surfaced as a sophisticated and well-resourced threat actor, conducting campaigns across at least 17 countries and multiple industries, with a strong focus on manufacturing, construction, healthcare, and insurance. First observed in August 2025, the group employed a broad range of advanced techniques, including legitimate driver exploitation, Group Policy manipulation, privileged account compromise, and the deployment of custom anti-AV utilities designed to disable specific security vendors. Their operations were marked by adaptability, with tools modified mid-campaign to better evade defenses, and detailed reconnaissance carried out to map Active Directory structures and privilege groups. Living-off-the-land techniques such as PsExec, PowerRun.exe, and registry modifications facilitated lateral movement, while persistence was maintained through AnyDesk installations and GPO abuse. Data staging and exfiltration were methodically executed using tools like Nmap, PuTTY, and WinSCP. Ultimately, ransomware payloads were distributed domain-wide via NETLOGON shares, aggressively terminating services, disabling Windows Defender, deleting forensic evidence, and encrypting files with password-protected executables before dropping ransom notes labeled README-GENTLEMEN.txt. The campaign reflects a shift away from broad, opportunistic ransomware toward highly tailored, environment-specific attacks.
Security Officer Comments:
The Gentlemen’s tactics underscore the rapid evolution of ransomware from commodity malware into targeted operations resembling advanced persistent threats. By developing custom tools against individual endpoint security vendors and combining them with the abuse of legitimate drivers and administrative utilities, the group demonstrates both high technical skill and significant financial backing. Their willingness to adapt in real time during campaigns, along with the use of encrypted exfiltration and persistent access channels, indicates operational maturity and a deliberate focus on ensuring success even in hardened environments.
Suggested Corrections:
Adopt Zero Trust principles: Eliminate direct RDP exposure to the internet, enforce MFA for all administrative accounts, and segment IT management tools from production systems to reduce the blast radius of a compromise.
Harden privileged accounts: Implement time-based access controls with automatic de-escalation, monitor for anomalous domain controller activity, and alert on bulk Active Directory queries or group membership changes.
Strengthen endpoint defenses: Enable tamper protection, agent self-protection, and application control on endpoint security solutions to prevent attackers from disabling defenses. Block execution of tools from temporary or download directories, and monitor for suspicious service termination attempts.
Control driver abuse: Enforce driver signature verification and monitor for attempts to load vulnerable or unsigned drivers, as The Gentlemen exploited legitimate drivers for defense evasion.
Enhance detection and response: Deploy behavioral detection for privilege escalation, credential dumping, and lateral movement activities. Use deception technologies on sensitive shares to catch reconnaissance early.
Secure exfiltration paths: Monitor encrypted outbound traffic for anomalies, paying special attention to file transfer tools like WinSCP or PuTTY, and restrict unauthorized remote access utilities such as AnyDesk.
Patch and monitor perimeter devices: Apply virtual patching and updates for VPN appliances, firewalls, and other internet-facing services. Continuously monitor for suspicious activity against these high-value entry points.
Link(s):
https://www.trendmicro.com/en_us/research/25/i/unmasking-the-gentlemen-ransomware.html