Bert ransomware group
Bert is one of the extortion operations we watch continuously. This page covers what is known about the group and the current state of its leak site, which we last saw change 1y ago.
Who they are
BERT ransomware (also tracked as Water Pombero) first emerged in April 2025, rapidly targeting both Windows and Linux systems across Asia, Europe, and the U.S., with confirmed victims in healthcare, technology, electronics, and event services sectors. Its Windows variant employs a PowerShell-based loader that escalates privileges, disables Defender, UAC, and the firewall, then downloads the ransomware payload. The Linux version aggressively encrypts with up to 50 concurrent threads, forcibly shuts down VMware ESXi VMs to prevent recovery, and appends extensions like .encryptedbybert or .encrypted_by_bert. BERT uses AES encryption, and later variants feature optimized multithreading via ConcurrentQueue and DiskWorker threads. Analysts note code similarities with REvil and Babuk ESXi lockers, potentially pointing to shared development lineage or code reuse.
Current status
Bert's leak site is not answering. Sites go dark for infrastructure trouble, a deliberate quiet period, or a takedown, and a good number return weeks later under the same name, so the entry stays on the list either way.
The last change we recorded on it was 1y ago (2 Aug 2025 18:14 UTC).
Which organisations this group has named, and when, is part of the SINON platform rather than this page. Create an account to search it, or to be told automatically if a name you care about turns up.
Sectors targeted
This group does not state an industry on its site, so we have nothing reliable to report. Most crews are opportunistic rather than sector-specific in any case — they hit what they can reach.
Watching for your name
If Bert posts your company, a supplier or a subsidiary, you want to hear it from us rather than from a journalist. SINON checks these sites continuously and alerts on the names you give it.
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