MountLocker is a ransomware operation that emerged in mid-2020 and was more prominently observed through early 2021, operating primarily with financial motivation through a Ransomware-as-a-Service model that recruited affiliates to conduct intrusions while the core developers maintained the malware and payment infrastructure. The group is believed to have Eastern European origins, and researchers at CrowdStrike and other firms noted operational and technical overlaps suggesting loose connections to other ransomware ecosystems active during the same period, though definitive attribution to a specific threat actor collective remains limited in public reporting. MountLocker affiliates were observed leveraging exposed Remote Desktop Protocol services and stolen credentials as primary initial access vectors, deploying the MountLocker encryptor alongside the AdFind Active Directory reconnaissance tool and legitimate remote administration utilities to facilitate lateral movement; the group practiced double extortion, exfiltrating sensitive data prior to encryption and threatening publication on a dedicated leak site to compel payment. Based on publicly available telemetry and reporting, the group accumulated at least 18 confirmed victims across manufacturing, construction, transportation and logistics, business services, and healthcare sectors, though no single campaign achieved the notoriety of contemporaneous groups such as REvil or Conti, and no record ransom figures were publicly disclosed. MountLocker's activity declined significantly through mid-2021, with the operation believed to have rebranded or dissolved, potentially transitioning into or merging with the AstroLocker and XingLocker variants that researchers observed using closely related code and infrastructure during the same timeframe. The group has been linked to 18 public disclosures across our corpus. First observed on a leak site on February 7, 2021; most recent post February 8, 2022. The operation is currently inactive.
Also tracked as: Mount Locker, Mount-Locker.
If your organisation is affected
A listing by mountlocker means ECU Worldwide 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.
- Monitor for the data appearing on mountlocker'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.
