⚠️ Overview

Egregor is a ransomware family first detected in September 2020, believed to be operated by a financially motivated threat group with ties to the defunct Maze ransomware operation. It belongs to the ransomware category and is classified under MITRE ATT&CK software ID S0554. Security vendors such as Trend Micro and CrowdStrike have linked Egregor to the same developers behind Maze and Sekhmet, noting shared code and infrastructure.

🔧 Technical Capabilities

Egregor performs double extortion by exfiltrating sensitive data before encrypting systems with AES-256 and RSA-4096 algorithms, then threatening to leak the data if the ransom is not paid. It propagates through RDP brute-force attacks, phishing emails with malicious attachments, and lateral movement using PsExec and WMI. The ransomware establishes persistence by modifying registry run keys and deleting volume shadow copies via vssadmin.exe. Its C2 infrastructure relies on encrypted HTTPS communication to exfiltrate data and receive encryption keys, while evasion techniques include disabling security services and process hollowing. Egregor also employs a custom binary that encrypts files and appends the .egregor extension, dropping a ransom note named RECOVER-FILES.txt.

📜 History & Notable Incidents

Egregor first emerged in September 2020, quickly gaining notoriety by targeting major corporations such as Ubisoft, Cephasonics, and Barnes & Noble. In November 2020, the group claimed responsibility for the breach of the Canadian video game company Ubisoft, leaking internal data. Law enforcement actions in February 2021, coordinated by Europol and the Ukrainian Cyber Police, led to the arrest of multiple individuals and the seizure of Egregor’s servers, effectively dismantling the operation. No specific CVEs were exclusively linked to Egregor; it relied on known vulnerabilities such as CVE-2019-19781 (Citrix ADC) and CVE-2020-1472 (Zerologon) for initial access in some campaigns.

🔍 Detection Indicators

Known file hashes include SHA256 values such as a3c8e2f1b0d4... (example from VirusTotal samples), though specific hashes vary per variant. Behavioral indicators include the creation of the mutex GlobalEgregor and the presence of files with the .egregor extension. Network indicators involve outbound connections to IP addresses associated with bulletproof hosting providers, often over HTTPS on port 443, and User-Agent strings mimicking legitimate browser traffic. Registry keys modified include HKCUSoftwareMicrosoftWindowsCurrentVersionRun to achieve persistence.

☠️ Risk & Impact

Egregor caused significant financial losses through ransom demands ranging from hundreds of thousands to millions of dollars, with victims across manufacturing, retail, healthcare, and software sectors. Data exfiltration exposed confidential customer information, financial records, and intellectual property, leading to additional regulatory fines and reputational damage. The double-extortion model increased pressure on victims to pay, as leaked data could be published on the group’s dedicated leak site.

🛡️ Mitigation

Defenders should implement multi-factor authentication on RDP, enforce least-privilege access, and maintain offline backups with regular testing. Detection can be enhanced using SIEM rules for lateral movement via PsExec and WMI, alongside endpoint detection and response (EDR) tools that flag the Egregor mutex and file extension. Patching known vulnerabilities (e.g., CVE-2020-1472) and disabling unused remote access services reduces the attack surface.

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