Ctblocker ransomware group
Ctblocker 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 2y ago.
Who they are
aka Critroni
CTB‑Locker emerged in mid‑2014, introducing a new era of ransomware by leveraging elliptic curve cryptography (ECC), Tor-based C&C communication, and Bitcoin payments—earning its name from “Curve-Tor-Bitcoin Locker.” It was packaged and sold as a ransomware kit for approximately $1,500–$3,000, allowing affiliates to deploy customized campaigns. The malware encrypts user data (including network and removable drives), changes desktop wallpapers, and appends file extensions like .CTBL, .CTB2, or randomized strings. Victims receive instructions for payment, typically within a limited timeframe, or risk permanent data loss. In 2015–2017, law enforcement and cybersecurity firms (including McAfee and Kaspersky) disrupted the network, arrested operators, and facilitated decryption tools.
Current status
Ctblocker'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 2y ago (12 Dec 2024 12:30 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 Ctblocker 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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