{
  "family": "cryptinject",
  "sample_count": 15,
  "category": "ransomware",
  "description": "Trojan:Win32/Cryptinject is a highly critical, generic heuristic classification utilized by Microsoft Defender to identify sophisticated, heavily encrypted executable files designed explicitly to inject malicious payloads directly into the memory space of legitimate system processes (Process Injection). This behavior is the hallmark of advanced threats like Emotet, Trickbot, and commercial adversary simulation tools like Cobalt Strike.<br><br><b>Understanding Cryptinject</b><br>To an end-user, a Cryptinject execution is completely invisible. For a security analyst, a Cryptinject alert is a massive red flag indicating a severe, likely hands-on-keyboard compromise. The malware is attempting a 'Fileless' execution strategy. By encrypting its core payload and injecting it straight into the memory of a trusted process (like `explorer.exe` or `svchost.exe`), it bypasses traditional file-based antivirus scanning and application whitelisting (AppLocker), as the malicious code never touches the disk in an unencrypted state.<br><br><b>Execution and Injection Mechanics</b><br>Cryptinject loaders are typically deployed via targeted spearphishing (weaponized Office macros) or by Initial Access Brokers (`T1566.001`). Upon execution, the loader (which is highly obfuscated, `T1027.002`) allocates a segment of memory within a target process using APIs like `VirtualAllocEx`. It then decrypts its internal payload (often a Cobalt Strike beacon) and writes it into that allocated space using `WriteProcessMemory`. Finally, it executes the payload via `CreateRemoteThread` or Asynchronous Procedure Calls (APC) (`T1055.001`). The now-infected legitimate process handles all subsequent Command and Control (C2) communication (`T1071.001`), making the outbound traffic appear highly benign.<br><br><b>Indicators of Compromise & Impact</b><br>The impact is a stealthy, persistent backdoor granting attackers full access to the endpoint, often serving as a precursor to enterprise ransomware deployment. EDR platforms must alert on anomalous API calls (`VirtualAllocEx` -> `WriteProcessMemory` -> `CreateRemoteThread`) originating from suspicious parent processes (like `winword.exe` spawning `powershell.exe`). Memory analysis (RAM dumping) is the *only* way to extract the unencrypted payload for reverse engineering.",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [],
  "enrichment_level": "expert-seo",
  "faq": [],
  "faq_count": 0,
  "mitre_attack": [
    "T1071.001",
    "T1027.002",
    "T1055.001",
    "T1566.001",
    "T1620"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-06-09",
  "mitre_attack_detail": [
    {
      "id": "T1055.001",
      "name": "Process Injection: Dynamic-link Library Injection",
      "tactic": "Defense Evasion"
    },
    {
      "id": "T1027.002",
      "name": "Obfuscated Files or Information: Software Packing",
      "tactic": "Defense Evasion"
    },
    {
      "id": "T1620",
      "name": "Reflective Code Loading",
      "tactic": "Defense Evasion"
    },
    {
      "id": "T1071.001",
      "name": "Application Layer Protocol: Web Protocols",
      "tactic": "Command and Control"
    },
    {
      "id": "T1566.001",
      "name": "Phishing: Spearphishing Attachment",
      "tactic": "Initial Access"
    }
  ],
  "containment_steps": [
    "Instantly isolate the endpoint; Cryptinject alerts are highly correlated with active Cobalt Strike beacons and imminent ransomware deployment.",
    "Do NOT attempt to manually terminate the injected system process (e.g., `svchost.exe`), as this will likely crash the operating system.",
    "Capture a full forensic memory image (RAM dump) immediately. This is critical for extracting the decrypted payload and identifying the C2 infrastructure.",
    "Initiate a hunt across the network for lateral movement (e.g., unusual SMB traffic, Pass-the-Hash) originating from the infected host."
  ],
  "what_to_avoid": [
    "Do not assume the threat is mitigated if the initial loader file is quarantined; the injected payload is already running in memory.",
    "Avoid relying solely on network blocklists; advanced injected payloads often use Domain Fronting or legitimate cloud services for C2."
  ],
  "target_industries": [
    "Global / Opportunistic"
  ],
  "motivation": "Opportunistic",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ]
}