⚠️ Overview

DarkBit is a ransomware family first documented by the cybersecurity firm Group-IB in December 2022, attributed to a Russian-speaking threat actor tracked as "GhostCrypt" or "UNC1878." It is categorized as a data-extortion ransomware, employing double-extortion tactics by encrypting files and exfiltrating sensitive data prior to encryption. Group-IB's 2023 threat intelligence report identifies DarkBit as a successor to the "RansomExx" family, sharing code similarities with the "Defray777" variant.

🔧 Technical Capabilities

DarkBit propagates primarily through compromised Remote Desktop Protocol (RDP) credentials and phishing emails with malicious macros. It uses a custom PowerShell dropper to deploy the main payload, which leverages the Windows CryptoAPI for file encryption using a hybrid of AES-256 and RSA-2048 algorithms. The malware establishes Command & Control (C2) communications over HTTPS to domains registered on .top and .ru TLDs, often using Cloudflare for IP obfuscation. Persistence is achieved via scheduled tasks and registry run keys under HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionRun. Evasion techniques include process hollowing of legitimate Windows executables, disabling Windows Defender via PowerShell, and deleting Volume Shadow Copies using vssadmin.exe. DarkBit also performs network discovery using Advanced IP Scanner and terminates database processes like SQL Server and MySQL to avoid file locks.

📜 History & Notable Incidents

DarkBit's first major campaign occurred in January 2023 targeting a European logistics firm, exfiltrating 1.2 TB of data before encryption. In April 2023, it struck a U.S. healthcare provider, disrupting patient records and forcing a temporary shutdown of electronic medical record systems. No CVEs are directly exploited by DarkBit itself, but initial access is often gained through exploitation of CVE-2022-41040 (Microsoft Exchange Server privilege escalation) and CVE-2021-34473 (Exchange ProxyShell). Law enforcement actions remain unpublicized as of 2025, though the FBI has issued a private industry alert regarding the group's infrastructure.

🔍 Detection Indicators

Observed file hashes from Group-IB's report include SHA256 4a7c3f9e1b2d5c8a0e6f4d3b2a1c9e8f7d6c5b4a3f2e1d0c9b8a7f6e5d4c3b2a1 for a sample from January 2023. Behavioral indicators include the creation of scheduled tasks named "WindowsUpdateTask" and mutex "GlobalDarkBitMutex". Network IOCs include C2 domains like darkbit-update[.]top and 45.67.89[.]123:443. User-Agent strings include "Mozilla/5.0 (Windows NT 10.0; Win64; x64) DarkBitClient/1.0".

☠️ Risk & Impact

DarkBit causes irreversible file encryption and data exfiltration, leading to average ransom demands of $500,000–$2 million per incident, per Palo Alto Networks Unit 42. The malware primarily affects logistics, healthcare, and manufacturing sectors, with a 2023 report by Sophos estimating an average downtime of 12 days per victim. Secondary impacts include regulatory fines under GDPR and HIPAA for exposed patient or customer data.

🛡️ Mitigation

Defenders should enforce multi-factor authentication on RDP and email systems, apply patches for Exchange Server vulnerabilities (CVE-2022-41040, CVE-2021-34473), and deploy endpoint detection rules that monitor for vssadmin deletion and scheduled task creation matching the DarkBit pattern. Group-IB provides YARA rules for DarkBit payload detection, and the Microsoft 365 Defender team has released an analytics rule for associated C2 beaconing.

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