{
  "family": "clhf",
  "sample_count": 1,
  "category": "ransomware",
  "description": "TrojanDownloader:Win32/Clhf is a specialized trojan designed to breach endpoint defenses and securely deliver secondary, high-severity payloads. Unlike a backdoor that provides interactive control, Clhf acts purely as an automated 'Initial Access Broker' tool. Its primary objective is to silently connect to a Command-and-Control (C2) server and pull down the final, destructive payload (such as ransomware, infostealers, or botnet clients) (`T1105`).<br><br><b>Understanding Clhf (Downloaders)</b><br>To an end-user, a Clhf infection is entirely invisible. The danger lies in what it brings with it. For an incident response team, the presence of Clhf indicates an active breach where the primary damage has likely not yet occurred, but is imminent. Detecting the downloader before it fetches the payload is critical.<br><br><b>Execution and Evasion Strategies</b><br>Clhf is commonly distributed via malspam campaigns containing weaponized attachments (like ZIP files or Office macros). Upon execution, it utilizes packing and obfuscation to evade static antivirus signatures (`T1027`). It drops a randomized executable into the `%Temp%` directory. To mask its outbound network traffic, Clhf frequently injects its downloading routine into legitimate system processes (like `svchost.exe` or `explorer.exe`) (`T1055`). It then makes HTTP/HTTPS GET requests to hardcoded or DGA-generated domains to fetch the payload.<br><br><b>Indicators of Compromise (IoCs)</b><br>Host-based IoCs include EDR alerts for 'Suspicious Process Injection' or legitimate processes making unexpected outbound network connections. The rapid creation of `.exe` or `.dll` files in the `%Temp%` or `%AppData%` directories by anomalous parent processes is a strong indicator. Network IoCs involve identifying the specific C2 domains or IP addresses Clhf contacts to fetch its payloads.",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [],
  "enrichment_level": "expert-seo",
  "faq": [],
  "faq_count": 0,
  "mitre_attack": [
    "T1105",
    "T1055",
    "T1027",
    "T1566.001"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-06-09",
  "mitre_attack_detail": [
    {
      "id": "T1105",
      "name": "Ingress Tool Transfer (The core function of fetching the secondary payload)",
      "tactic": "Command and Control"
    },
    {
      "id": "T1055",
      "name": "Process Injection (Injecting into svchost.exe to hide network traffic)",
      "tactic": "Defense Evasion"
    },
    {
      "id": "T1566.001",
      "name": "Phishing: Spearphishing Attachment (Primary distribution vector)",
      "tactic": "Initial Access"
    },
    {
      "id": "T1027",
      "name": "Obfuscated Files or Information (Packing the downloader to bypass AV)",
      "tactic": "Defense Evasion"
    }
  ],
  "containment_steps": [
    "Isolate the endpoint immediately; if Clhf is detected, you must assume it is actively attempting to download a worse payload.",
    "Analyze EDR and proxy logs to identify the C2 domains Clhf contacted, and block those domains enterprise-wide.",
    "Determine if the secondary payload was successfully downloaded and executed; if so, shift response efforts to containing the final payload (e.g., ransomware).",
    "Hunt for the specific spearphishing email that delivered Clhf and purge it from all user inboxes."
  ],
  "what_to_avoid": [
    "Do not close the incident simply because the AV quarantined the Clhf executable; you must verify network logs to ensure the payload wasn't already downloaded.",
    "Avoid relying solely on static AV signatures, as downloaders are frequently repacked."
  ],
  "target_industries": [
    "Global / Opportunistic"
  ],
  "motivation": "Opportunistic",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ]
}