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BERT, also tracked by Trend Micro as Water Pombero, is a financially motivated ransomware group first observed in April 2025. It targets organizations in Asia, Europe, and the United States, including healthcare, technology, and event-services organizations. The group deploys ransomware for Windows and Linux, including VMware ESXi environments. BERT's Windows deployment uses a PowerShell loader that attempts to obtain elevated execution and disables Microsoft Defender, Windows Firewall, and User Account Control before downloading and executing the ransomware. The Windows payload terminates processes associated with web servers, databases, and other critical services and encrypts files using AES. Its encryption implementation evolved from collecting target file paths before encryption to processing discovered files concurrently with per-drive workers. The Linux variant, identified in May 2025, supports configurable encryption paths, thread counts, and silent execution, with 50 encryption threads by default. In non-silent mode, it enumerates and forcibly terminates running ESXi virtual machines before encrypting files. Both platform variants leave ransom notes. BERT's initial-access methods and geographic origin remain unestablished.
Mallory correlates actor tradecraft and target patterns against your stack, your sector, and your geography. See overlap before they land.
Who, where, and (when attributed) which flag flies behind the operation. Pulled from open-source reporting and Mallory's analyst review.
Sectors the actor has been observed targeting.
Geographies tied to known operations.
12 distinct techniques observed across reporting, grouped by tactic. Hover any cell for the evidence excerpt; click through for MITRE's full description.
1 malware family attributed to this actor across reporting.
1 indicator attributed to this actor: domains, IPs, hashes, and other artifacts pulled from reporting. View more in app.
4 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
Named as a new ransomware variant/gang emerging in 2024 and associated with victim claims posted in April 2024.
A newly emerged cross-platform ransomware operation conducting attacks against organizations in Asia, Europe, and the United States. It uses Windows PowerShell loaders to disable defenses and elevate privileges, and Windows and Linux encryptors optimized for concurrent encryption. Its Linux variant targets ESXi environments and forcibly terminates virtual machines before encryption.
The bert ransomware leak site lists S5 Agency World as a victim, identifying it as a UK-based global port agency operating in over 360 ports. The post provides basic victim attribution and domain information but does not state any ransom demand, deadline, data volume, or proof of stolen data.
Newly emerged ransomware group (no specific victimology or TTPs detailed in the content).
Match sector + geo + tech-stack targeting against your real footprint.
Every observed MITRE ATT&CK technique, grouped by tactic.
Families this actor is known to deploy, with IOCs and behavior.
CVEs this actor has used in known campaigns.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Domains, IPs, and hashes tied to this actor, refreshed continuously.