{
  "family": "hostschanger",
  "sample_count": 3,
  "category": "advanced_threat",
  "description": "HackTool:Win32/Hostschanger is a critical **Heuristic Detection** that flags any unauthorized software attempting to maliciously modify the `C:\\Windows\\System32\\drivers\\etc\\hosts` file. While legitimate IT administration scripts sometimes modify this file, malware heavily abuses it to redirect network traffic at the local DNS level, enabling severe phishing attacks, ad-fraud, and defense evasion.<br><br><b>Understanding Hostschanger (DNS Hijacking)</b><br>To an end-user, an infection might cause them to see a fake banking login page even though they typed the correct URL, or they might find themselves unable to access antivirus update sites. For a security analyst, a Hostschanger alert indicates a successful compromise of DNS resolution at the OS level (`T1562.004`). By overriding the DNS cache, the attacker controls where the victim's browser goes for specific domains.<br><br><b>Execution and Hijacking Mechanics</b><br>Upon execution (`T1204.002`), the malware (which must run with Administrator privileges) opens the `hosts` file and appends new entries. The two most common scenarios are: 1) **Defense Evasion (`T1562.001`)**: Routing requests for `update.microsoft.com` or `liveupdate.symantec.com` to `127.0.0.1` (localhost), effectively blinding the endpoint's security software by preventing updates. 2) **Phishing/Fraud**: Routing requests for `www.chase.com` to a malicious IP address controlled by the attacker, serving a perfect replica of the banking site to steal credentials. Because the hosts file supersedes DNS, the browser will show the correct URL in the address bar, making the phishing attack highly convincing.<br><br><b>Indicators of Compromise & Impact</b><br>The impact ranges from a disabled antivirus agent to severe credential theft. Host-based IoCs include EDR alerts for processes editing the `hosts` file, and the presence of anomalous IP mappings within the file itself. Network IoCs might show the endpoint communicating with unknown IP addresses over port 443 when attempting to reach known, legitimate domains.",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [],
  "enrichment_level": "expert-seo",
  "faq": [
    {
      "@type": "Question",
      "name": "What is Hostschanger and what threat category does it belong to?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Hostschanger is classified as a Advanced Threat. 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 Hostschanger establish persistence and evade defensive controls?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Hostschanger 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 Hostschanger compromise?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Security teams responding to Hostschanger 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 lateral movement and credential access tactics does Hostschanger leverage in enterprise intrusions?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Hostschanger frequently utilizes privileged account harvesting techniques such as LSASS memory dumping, Kerberoasting, and token impersonation to escalate privileges. Once administrative credentials are acquired, it pivots across the victim network utilizing living-off-the-land binaries (LOLBins) such as WMI, PowerShell remoting, and PsExec, or abuses remote desktop protocols (RDP) to reach critical internal repositories and domain controllers."
      }
    },
    {
      "@type": "Question",
      "name": "How does Hostschanger maintain covert communications and evade perimeter network monitoring?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Hostschanger often relies on multi-stage command and control (C2) architectures utilizing encrypted protocols over standard web ports (HTTPS/443 or DNS tunneling) to blend in with legitimate enterprise network traffic. Many variants incorporate proxy networks, domain fronting, or cloud services (such as Microsoft Graph API, Google Drive, or Telegram) to masquerade C2 channels, bypassing traditional signature-based egress filtering."
      }
    }
  ],
  "faq_count": 5,
  "mitre_attack": [
    "T1204.002",
    "T1562.001",
    "T1562.004"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-06-09",
  "mitre_attack_detail": [
    {
      "id": "T1562.004",
      "name": "Impair Defenses: Disable or Modify System Firewall (Modifying Hosts File)",
      "tactic": "Defense Evasion"
    },
    {
      "id": "T1562.001",
      "name": "Impair Defenses: Disable or Modify Tools (Blocking AV updates)",
      "tactic": "Defense Evasion"
    },
    {
      "id": "T1204.002",
      "name": "User Execution: Malicious File",
      "tactic": "Execution"
    }
  ],
  "containment_steps": [
    "Immediately isolate the endpoint, as its DNS resolution is compromised and it may be communicating with attacker-controlled infrastructure.",
    "Open `C:\\Windows\\System32\\drivers\\etc\\hosts` with a text editor (as Administrator) and remove any unauthorized entries, restoring it to default.",
    "Run a full system scan with an updated enterprise EDR solution to locate and remove the malware that performed the modification.",
    "Initiate a password reset for any critical accounts (e.g., banking, corporate VPN) the user accessed while the machine was infected."
  ],
  "what_to_avoid": [
    "Do not trust the web browser on an infected machine; even if the URL looks correct and has a padlock, the traffic may be routed to a malicious server.",
    "Avoid simply fixing the hosts file without finding the root cause; the malware will likely just modify it again on the next reboot."
  ],
  "target_industries": [
    "Global / Opportunistic"
  ],
  "motivation": "Opportunistic",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ],
  "attack_stage": [
    "execution",
    "persistence"
  ],
  "ecosystem": [
    "windows_pe"
  ],
  "is_emerging": false,
  "target_platforms": [
    "Windows 11",
    "Windows 10",
    "Windows Server 2022",
    "Windows Server 2019"
  ]
}