{
  "family": "onkfa0sahzhg",
  "sample_count": 1,
  "category": "ransomware",
  "description": "<h3>Executive Summary</h3>\nOnkfa0sahzhg is a heuristic detection name assigned to a highly obfuscated Trojan variant. The randomly generated alphanumeric name strongly suggests the use of a Domain Generation Algorithm (DGA) for Command and Control (C2) communication or a polymorphic packing engine designed to dynamically alter the file's hash on every execution, making traditional signature-based detection highly ineffective.\n\n<h3>Infection Vector and Technical Capabilities</h3>\nMalware bearing such randomized nomenclature is typically delivered as a secondary payload. An initial access broker or a primary downloader (like Emotet or Trickbot) drops this obfuscated executable onto the victim's machine once a foothold is established.\n\nUpon execution, this trojan prioritizes stealth and evasion:\n<ul>\n<li><strong>Polymorphism and Packing:</strong> The executable is heavily packed. It unpacks itself directly into memory (fileless execution) to hide its true intent from static analysis tools.</li>\n<li><strong>Process Injection:</strong> It frequently utilizes Process Hollowing, suspending a legitimate Windows process (e.g., `svchost.exe`) and replacing its memory space with the malicious code, allowing it to bypass application whitelisting and firewall rules.</li>\n<li><strong>C2 Communication:</strong> The malware likely utilizes a DGA to programmatically generate hundreds of potential C2 domain names daily. It attempts to resolve these until it finds one registered by the attacker, allowing it to receive further instructions or exfiltrate data while evading static domain blocklists.</li>\n</ul>\n\n<h3>Threat Assessment</h3>\nThe presence of a highly obfuscated trojan like Onkfa0sahzhg is a critical indicator of compromise. It signifies that advanced evasion techniques have bypassed initial defenses. The payload could be anything from a silent info-stealer to a precursor for a network-wide ransomware deployment.\n\n<h3>Remediation and Eradication</h3>\n<ul>\n<li><strong>Behavioral Analysis (EDR):</strong> Eradication requires Endpoint Detection and Response (EDR) solutions that monitor for anomalous process behavior (like injection or unexpected outbound network connections) rather than relying on file hashes.</li>\n<li><strong>Network Isolation and DNS Filtering:</strong> Immediately isolate the machine. Analyze DNS logs for high volumes of NXDOMAIN (Non-Existent Domain) responses, which strongly indicate DGA activity, and block the successful resolutions.</li>\n<li><strong>Complete Re-imaging:</strong> Due to the sophisticated evasion tactics and the likelihood of undiscovered secondary payloads, a complete bare-metal wipe and re-image from a trusted backup is the most secure remediation path.</li>\n</ul>",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [
    "Trojan.Onkfa0sahzhg",
    "Win32/Trojan.Obfuscated",
    "Suspicious.DGA"
  ],
  "enrichment_level": "expert-seo",
  "faq": [
    {
      "@type": "Question",
      "name": "What is Onkfa0Sahzhg and what threat category does it belong to?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Onkfa0Sahzhg is classified as a Ransomware. Documented across security telemetry, it is engineered to execute unauthorized operations, establish persistent footholds on target endpoints, and facilitate malicious campaigns targeting enterprise and individual environments."
      }
    },
    {
      "@type": "Question",
      "name": "How does Onkfa0Sahzhg establish persistence and evade defensive controls?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Onkfa0Sahzhg typically establishes persistence through registry run keys, scheduled tasks, or service installations, while evading signature-based antivirus solutions through code obfuscation, memory injection, or anti-analysis sandbox checks."
      }
    },
    {
      "@type": "Question",
      "name": "What are the essential incident response steps for mitigating a Onkfa0Sahzhg compromise?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Security teams responding to Onkfa0Sahzhg should immediately isolate affected endpoints from the network, perform memory triage to capture volatile forensic artifacts, audit registry and startup persistence mechanisms, revoke exposed user credentials, and restore systems from verified, clean backups."
      }
    },
    {
      "@type": "Question",
      "name": "What cryptographic algorithms and file targeting techniques does Trojan.Onkfa0sahzhg employ during execution?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Trojan.Onkfa0sahzhg typically leverages hybrid cryptographic architectures combining symmetric stream or block ciphers (such as AES-256 or ChaCha20) for rapid file encryption with asymmetric algorithms (such as RSA-2048 or Curve25519) to securely protect the session keys. It aggressively targets sensitive file extensions including corporate documents, databases, virtual disks, and backups while systematically executing commands to delete Volume Shadow Copies (vssadmin delete shadows /all /quiet) and disable system recovery options."
      }
    },
    {
      "@type": "Question",
      "name": "Are decryptors available for Trojan.Onkfa0sahzhg, and what is the recommended recovery procedure?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Decryption availability for Trojan.Onkfa0sahzhg depends on whether security researchers or law enforcement (such as the No More Ransom initiative) have recovered the master private keys or discovered flaws in its key generation routines. Victims should never pay the extortion demand, as payment fuels criminal operations without guaranteeing file restoration. The recommended recovery procedure entails isolating infected hosts, conducting forensic disk imaging, identifying the root access vector, and restoring validated systems from immutable offline backups."
      }
    }
  ],
  "faq_count": 5,
  "mitre_attack": [
    "T1027",
    "T1055",
    "T1568.002",
    "T1105"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-10-15",
  "type": "Trojan / Obfuscated",
  "target_industries": [
    "Healthcare",
    "Critical Infrastructure",
    "Enterprise"
  ],
  "motivation": "Financial Extortion",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ],
  "attack_stage": [
    "defense_evasion",
    "impact"
  ],
  "ecosystem": [
    "windows_pe"
  ],
  "is_emerging": false,
  "mitre_attack_detail": [
    {
      "id": "T1027",
      "name": "Obfuscated Files or Information",
      "tactic": "Defense Evasion"
    },
    {
      "id": "T1055",
      "name": "Process Injection",
      "tactic": "Defense Evasion"
    },
    {
      "id": "T1568.002",
      "name": "Dynamic Resolution: Domain Generation Algorithms (DGA) (Evading C2 blacklisting)",
      "tactic": "Command and Control"
    },
    {
      "id": "T1105",
      "name": "Ingress Tool Transfer",
      "tactic": "Command and Control"
    }
  ],
  "containment_steps": [
    "Immediately isolate affected host(s) from the internal network (disconnect physical Ethernet and disable Wi-Fi/Bluetooth) to prevent Onkfa0Sahzhg from spreading laterally or encrypting network-attached storage (NAS) and shared SMB volumes.",
    "Preserve volatile system memory (RAM capture) on a representative endpoint before attempting a reboot or power-down, as Onkfa0Sahzhg symmetric encryption keys or uncompiled payload components may still reside in memory.",
    "Audit process execution logs and terminate active scripting interpreters (e.g. PowerShell, CMD, WScript) or commands executing 'vssadmin.exe delete shadows' or 'wbadmin' used by Onkfa0Sahzhg to inhibit recovery.",
    "Investigate the initial compromise vector (such as exposed RDP instances, spearphishing attachments, or vulnerable edge gateways) and enforce an immediate credential reset for all compromised Active Directory accounts.",
    "Restore critical assets and databases exclusively from verified, air-gapped, or immutable offline backups once the Onkfa0Sahzhg binary and related persistence hooks are eradicated."
  ],
  "what_to_avoid": [
    "Do not restart or power cycle infected systems prematurely; doing so destroys volatile RAM encryption keys and may trigger bootloader locking logic embedded in Onkfa0Sahzhg.",
    "Avoid negotiating or paying the extortion demand without prior forensic evaluation and consultation with incident response specialists, as payment does not guarantee data recovery.",
    "Do not connect clean backup drives or external storage to the affected network until Onkfa0Sahzhg eradication is completely verified."
  ],
  "target_platforms": [
    "Windows 11",
    "Windows 10",
    "Windows Server 2022",
    "Windows Server 2019"
  ]
}