Clop (also stylized as "Cl0p") is a financially motivated ransomware group and cybercriminal enterprise that emerged in early 2020 as an evolution of the earlier CryptoMix ransomware family, operating primarily for monetary extortion against large enterprise targets. The group is widely assessed by Mandiant, CISA, and other reputable researchers to have ties to Russian-speaking cybercriminal actors, with some researchers linking their operations to the broader FIN11 threat cluster; they operate a Ransomware-as-a-Service (RaaS) model while also conducting direct intrusion operations. Clop is particularly distinguished for its aggressive exploitation of zero-day and n-day vulnerabilities in managed file transfer (MFT) and enterprise software platforms as primary initial access vectors, most notably the exploitation of Accellion FTA (2020-2021), Fortra GoAnywhere MFT (CVE-2023-0669), and the MOVEit Transfer vulnerability (CVE-2023-34362) in 2023, and consistently employs double extortion tactics — exfiltrating sensitive data prior to or in lieu of encryption and threatening public disclosure on their dedicated leak site to coerce payment. Clop has been responsible for some of the most impactful ransomware campaigns on record, with their 2023 MOVEit exploitation campaign alone affecting over 1,000 organizations globally and impacting entities including Shell, the U.S. Department of Energy, British Airways, and numerous U.S. federal agencies, with the broader campaign representing one of the largest mass-exploitation events in ransomware history; Ukrainian law enforcement arrested six individuals linked to Clop operations in June 2021, though the group's core leadership is assessed to remain outside of effective law enforcement jurisdiction. As of the most recent publicly available intelligence, Clop remains active, continuing to leverage vulnerability exploitation campaigns against enterprise file transfer solutions and maintaining a victim count exceeding 1,250 known organizations, with consistent targeting concentrated in the United States, Canada, United Kingdom, Australia, and Germany across technology, business services, manufacturing, and consumer services sectors. The group has been linked to 1,254 public disclosures across our corpus. First observed on a leak site on March 13, 2020; most recent post May 1, 2026. The operation is currently active.
Also tracked as: Cl0p.
Sector and geography
This disclosure adds to ransomware activity in the Construction sector, which has 988 disclosures indexed across all operators we track. Geographically, COBU-ARCH.COM is reported in Japan, a country with 88 ransomware disclosures in our corpus.
If your organisation is affected
A listing by clop means COBU-ARCH.COM appeared on a ransomware extortion site and data attributed to it has been published. If this is your organisation, or a supplier you depend on, the priority is to confirm the intrusion and contain it before the window to act closes.
- Engage your incident-response team and preserve forensic evidence before remediating — do not wipe affected systems first.
- Force a password reset and revoke active sessions for exposed accounts; rotate any credentials, API keys or certificates that may have been in the stolen data.
- Assess regulatory notification duties (GDPR, NIS2, sector regulators) — many carry a 72-hour reporting clock from awareness.
- Report the incident to your national CERT, JPCERT/CC (Japan), as required for your jurisdiction.
- Monitor for the data appearing on clop's leak site and across paste and breach channels, and brief downstream partners who may be exposed through you.
How we know this. Darkfield monitors public ransomware leak sites continuously, archiving every new disclosure and the data later released against the victim. Each entry on this page is sourced from the operator's own publication and cross-checked against complementary OSINT feeds (RansomLook, ransomware.live, RansomWatch). We do not collect or host stolen data — only the metadata, timestamps and screenshots needed to make the public disclosure searchable and accountable. Records here are corrected when the original post is edited, retracted, or merged with another disclosure.
