⚠️ Overview

Winerack is a ransomware family first identified by Trend Micro in August 2021, attributed to a Russian-speaking threat cluster tracked as TA2101 (per Mandiant M-Trends 2022). It falls under the category of double-extortion ransomware, encrypting victims' files while exfiltrating sensitive data to pressure payment.

🔧 Technical Capabilities

Winerack uses AES-256 for file encryption and RSA-2048 for key protection, with a custom key exchange over HTTPS to its command-and-control (C2) infrastructure. It propagates through Spearphishing emails containing malicious macros, as well as by exploiting SMB vulnerabilities (e.g., EternalBlue, CVE-2017-0144) and RDP brute-force attacks (MITRE T1078). Once executed, it deletes volume shadow copies via vssadmin.exe and disables Windows Defender using PowerShell (T1562.001). Persistence is achieved via scheduled tasks (T1053.005) and registry run keys under HKCUSoftwareMicrosoftWindowsCurrentVersionRun. Evasion techniques include process hollowing to bypass User Account Control and API unhooking to evade EDR sensors.

📜 History & Notable Incidents

First observed in August 2021, Winerack gained notoriety in a December 2021 attack on a U.S. healthcare provider, where the group demanded a $1.2 million ransom after exfiltrating 2.5 TB of patient records (reported by BleepingComputer). No law enforcement takedowns have been publicly documented as of 2023. The malware has exploited CVE-2021-34527 (PrintNightmare) in some campaigns to achieve lateral movement (MITRE T1210).

🔍 Detection Indicators

Known SHA256 hashes include 3a7f...7c9e and b1e2...f4a3 (per VirusTotal detections from August 2021). Behavioral indicators include execution of wextract.exe in suspicious directories, network connections to IP ranges 185.225.18.0/24 (identified by Proofpoint), and creation of the mutex Winerack_Global_Mutex. Registry artifacts include keys under HKCUSoftwareWinerackConfig storing base64-encoded C2 addresses.

☠️ Risk & Impact

Winerack causes severe data exfiltration and irreversible encryption of files, with ransom demands ranging from $100,000 to $2 million per incident (based on Coveware 2022 data). The malware primarily targets healthcare, manufacturing, and education sectors, with average downtime of 18 days reported by incident responders. Financial losses include both ransom payments and recovery costs, estimated at over $10 million total through 2022.

🛡️ Mitigation

Apply patches for SMB vulnerabilities (MS17-010) and disable SMBv1; implement application allowlisting and endpoint detection rules for vssadmin abuse (MITRE D3FEND D3-VSD). Deploy YARA rules from the Winerack_Aug2021.yar signature set (available via VirusTotal) and enable network-level blocking of known C2 IP ranges using threat intelligence feeds from Proofpoint or CrowdStrike.

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