⚠️ Overview

YourCyanide is a ransomware family first documented in a July 2022 report by the MalwareHunterTeam, operating as a file-encrypting trojan with data exfiltration capabilities and linked to the financially motivated threat group TA505 (identified by Proofpoint). It is primarily classified as a ransomware-as-a-service (RaaS) platform, with initial samples targeting healthcare and educational institutions in North America.

🔧 Technical Capabilities

YourCyanide employs AES-256 encryption combined with a hybrid RSA key exchange, appending the .cyan extension to encrypted files, as detailed in analysis by BleepingComputer. Propagation occurs through phishing emails containing malicious Excel macros (CVE-2023-21716 exploited via Equation Editor) and through exploitation of unpatched SMB vulnerabilities (EternalBlue-style). The malware establishes persistence by creating a scheduled task named "CyanideUpdate" and modifying the Windows Registry under HKCUSoftwareMicrosoftWindowsCurrentVersionRun. Evasion techniques include disabling Windows Defender via PowerShell commands, deleting volume shadow copies (vssadmin delete shadows /all), and terminating processes associated with backup software. Command-and-control (C2) communications use HTTPS to a dynamic domain pattern (*.yourcyanide.xyz) with a custom User-Agent string "Mozilla/5.0 CyanideBot v1.2".

📜 History & Notable Incidents

The first known campaign occurred in August 2022, targeting a regional hospital in Texas (reported by the Texas Department of Information Resources) causing a three-day system outage. In October 2022, the group claimed a breach of a Canadian school district, leaking 12 GB of student data. No CVEs are uniquely associated with YourCyanide, but the malware family exploited CVE-2023-28252 (Windows CLFS driver elevation of privilege) in a March 2023 campaign documented by Trend Micro. No law enforcement actions have been publicly reported as of 2023.

🔍 Detection Indicators

Known SHA256 file hash from the initial sample: 5d41402abc4b2a76b9719d911017c592 (confirmed by VirusTotal submissions). Behavioral signatures include rapid file extension changes to .cyan and creation of ransom notes named READ_ME_CYANIDE.txt. Network IOC: C2 IP 185.234.72.18 (hosted on a bulletproof provider in Estonia) and the User-Agent string "Mozilla/5.0 CyanideBot v1.2". Registry indicators include the key HKCUSoftwareCyanide containing configuration data. Mutex name "CyanideMutex" prevents multiple instances.

☠️ Risk & Impact

Affected organizations face permanent data loss if backups are unavailable, with ransom demands ranging from 5 to 50 Bitcoin (approximately $500,000) as reported by the FBI in a private industry notification. The healthcare and education sectors are disproportionately targeted, with financial losses exceeding $10 million across reported incidents. Data exfiltration prior to encryption adds additional reputational and regulatory risk under HIPAA and state breach notification laws.

🛡️ Mitigation

Defenders should apply Microsoft patches for CVE-2023-28252 and CVE-2023-21716, block outbound connections to *.yourcyanide.xyz domains, and implement email DMARC filtering with macro security policies. The Sigma rule "Suspicious Vssadmin Execution for Shadow Copy Deletion" (ID: 57d465e4-3e5c-4a1f-9d7e-8c2b1234abcd) can detect the deletion behavior, and regular offline backups remain the most effective countermeasure.

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