Hostschanger

Overview

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.

Understanding Hostschanger (DNS Hijacking)
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.

Execution and Hijacking Mechanics
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.

Indicators of Compromise & Impact
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.

MITRE ATT&CK Techniques

Observed techniques used by this family, mapped to the MITRE ATT&CK framework:

Generated Detections (Boilerplate)

These YARA and Sigma rules are auto-generated based on the family name and aliases. They must be heavily tuned before deployment in a production environment.

YARA Rule

rule MALWARE_WIN_HOSTSCHANGER {
    meta:
        description = "Detects Hostschanger (advanced_threat)"
        author = "SystemHelpdesk Boilerplate Generator"
        date = "2026-07-06"
    strings:
        $s1 = "hostschanger" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

Sigma Rule

title: Suspicious Hostschanger Activity
id: 8637d52773ca0274b87b2f53eb3afa98
status: experimental
description: Detects generic indicators of the hostschanger malware family.
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith:
            - '\cmd.exe'
            - '\powershell.exe'
        CommandLine|contains:
            - "*hostschanger*"
    condition: selection
level: medium

Containment & Response Steps

Ordered checklist for responders. Adapt to your environment and engage professional support for active incidents.

1. Immediately isolate the endpoint, as its DNS resolution is compromised and it may be communicating with attacker-controlled infrastructure.
2. Open `C:\Windows\System32\drivers\etc\hosts` with a text editor (as Administrator) and remove any unauthorized entries, restoring it to default.
3. Run a full system scan with an updated enterprise EDR solution to locate and remove the malware that performed the modification.
4. Initiate a password reset for any critical accounts (e.g., banking, corporate VPN) the user accessed while the machine was infected.

What to Avoid

Common mistakes during response to this family that can destroy evidence, spread the infection, or worsen recovery.

1. 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.
2. Avoid simply fixing the hosts file without finding the root cause; the malware will likely just modify it again on the next reboot.

References & External Analysis

• Search "hostschanger" on VirusTotal (External Analysis)

Frequently Asked Questions

Related Families (Category: advanced_threat)

Explore other malware families in the same category:

• Sogou
• Chromepass
• Globalacces
• Brambul
• Xmrigminer

Machine-readable

Get this profile as JSON: https://jordan123234-malware-families-explorer.static.hf.space/api/hostschanger.json

Ecosystem & Interactive Environments

This profile is part of the Malware Families Catalog, a public dataset of 2,899 malware families. The catalog is also published across our ecosystem: Hugging Face, Kaggle, Zenodo, Replit, StackBlitz, CodeSandbox, and CodePen.