{
  "family": "dllhijack",
  "sample_count": 1,
  "category": "ransomware",
  "description": "Exploit:Win32/Dllhijack refers not to a specific malware family, but to a critical execution and defense evasion technique (`T1574.001` - DLL Search Order Hijacking). Antivirus engines use this detection when they observe a known good, legitimate application (like a signed Microsoft binary or a popular third-party tool) being manipulated to load a malicious Dynamic Link Library (DLL) instead of its intended, legitimate DLL.<br><br><b>Understanding DLL Hijacking (Defense Evasion)</b><br>To an end-user, the infection is entirely invisible. For a security team, a Dllhijack detection is a severe warning that an attacker is utilizing advanced 'Living off the Land' (LotL) techniques. Because the malicious code runs inside the memory space of a trusted, digitally signed process, it easily bypasses basic AV signatures, application whitelisting (AppLocker), and often blends in with normal EDR logs.<br><br><b>Execution and Evasion Mechanics</b><br>When a Windows application needs to load a DLL, it searches directories in a specific order (the directory the app was launched from, then System32, then the Windows folder, etc.). Attackers exploit this by dropping a malicious DLL (named identically to a required system DLL, e.g., `version.dll` or `cryptbase.dll`) into the same directory as the vulnerable application. When the legitimate application runs, it unknowingly loads the attacker's DLL first, executing the malicious payload (like Cobalt Strike or a ransomware encryptor).<br><br><b>Indicators of Compromise & Impact</b><br>The impact is total system compromise, achieved stealthily. Host-based IoCs include the presence of unsigned DLLs residing in directories where they do not belong (e.g., a system DLL sitting in `%AppData%` next to a copied legitimate executable). EDR solutions must analyze image load events to detect unsigned modules loading into signed processes. Process Explorer can be used to verify the digital signatures of all loaded modules for a suspected process.",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [],
  "enrichment_level": "expert-seo",
  "faq": [],
  "faq_count": 0,
  "mitre_attack": [
    "T1055.001",
    "T1574.001",
    "T1574.002"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-06-09",
  "mitre_attack_detail": [
    {
      "id": "T1574.001",
      "name": "Hijack Execution Flow: DLL Search Order Hijacking (The core technique being detected)",
      "tactic": "Defense Evasion"
    },
    {
      "id": "T1574.002",
      "name": "Hijack Execution Flow: DLL Side-Loading (A closely related technique)",
      "tactic": "Defense Evasion"
    },
    {
      "id": "T1055.001",
      "name": "Process Injection: Dynamic-link Library Injection (The ultimate result of the hijack)",
      "tactic": "Defense Evasion"
    }
  ],
  "containment_steps": [
    "Isolate the endpoint immediately; if DLL hijacking is detected, the attacker has likely already achieved persistence or is moving laterally.",
    "Identify the legitimate application that was abused and the malicious DLL that was loaded.",
    "Analyze the malicious DLL in a sandbox to determine what payload it actually executed (e.g., C2 beaconing, encryption).",
    "Implement strong folder permissions to prevent standard users from writing DLLs into application installation directories."
  ],
  "what_to_avoid": [
    "Do not assume the legitimate, signed application is the virus; deleting `explorer.exe` because it loaded a bad DLL will break the system.",
    "Avoid relying solely on static file hashes for detection, as attackers frequently recompile the malicious DLLs."
  ],
  "target_industries": [
    "Global / Opportunistic"
  ],
  "motivation": "Opportunistic",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ]
}