Dnschanger

Overview

Trojan:Win32/Dnschanger is a historically massive and highly impactful malware family that formed the core of **Operation Ghost Click**. Between 2007 and 2011, it infected over 4 million computers globally. Its sole, devastating purpose was to silently modify the Windows TCP/IP settings, redirecting the victim's Domain Name System (DNS) queries to rogue servers controlled by a cybercriminal syndicate. This allowed the attackers to hijack web traffic, inject ads, and prevent users from accessing antivirus updates.

Understanding Dnschanger (Ghost Click)
To a victim, the internet would slowly become degraded. They would be redirected to fake websites (phishing) when trying to access their bank, or bombarded with injected advertisements on legitimate sites. For a security analyst, DNS hijacking is a fundamental breach of network trust. By controlling DNS, the attacker controls reality for the infected machine, routing them away from legitimate infrastructure entirely.

Execution and Hijacking Mechanics
Dnschanger was distributed massively via drive-by downloads, exploit kits, and bundled adware (`T1189`). Upon execution, the malware's primary action is to interface with the Windows Registry or the `netsh` utility. It specifically targets the `NameServer` values under `HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\` (`T1562.001`, `T1498`). It replaces the user's legitimate, ISP-provided DNS server IPs with IPs pointing to the attacker's rogue DNS infrastructure in Estonia or New York. From that point on, every time the user types 'google.com', the rogue server resolves it to a malicious IP. The malware also aggressively blocked access to known antivirus update domains (`T1562.004`).

Indicators of Compromise & Impact
The impact was a total compromise of network routing for millions of users. The primary IoC was the presence of known rogue IP addresses (e.g., `85.255.112.0/20`) configured as the primary/secondary DNS servers in the Windows network adapter settings. Network logs would show all DNS traffic (Port 53) routing to these anomalous subnets rather than corporate or ISP resolvers.

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_DNSCHANGER {
    meta:
        description = "Detects Dnschanger (trojan)"
        author = "SystemHelpdesk Boilerplate Generator"
        date = "2026-07-06"
    strings:
        $s1 = "dnschanger" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

Sigma Rule

title: Suspicious Dnschanger Activity
id: 12faf874e4f46b4a53b9db9471fb3f99
status: experimental
description: Detects generic indicators of the dnschanger malware family.
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith:
            - '\cmd.exe'
            - '\powershell.exe'
        CommandLine|contains:
            - "*dnschanger*"
    condition: selection
level: medium

Containment & Response Steps

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

1. Open the Windows Network Adapter settings (or `ipconfig /all`) and verify the configured DNS servers against known good corporate or ISP resolvers.
2. If rogue IPs are found, flush the DNS cache (`ipconfig /flushdns`) and manually reset the adapter settings to use DHCP or legitimate DNS servers (like 8.8.8.8).
3. Run a full antivirus scan to remove the underlying trojan that caused the modification; simply changing the DNS back is insufficient if the malware is still running.
4. Monitor enterprise DNS logs for any endpoints attempting to resolve queries against the known rogue Dnschanger subnets.

What to Avoid

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

1. Do not assume the internet is 'just broken'; a sudden inability to reach specific sites (especially AV vendors) while others work is a classic sign of DNS hijacking.
2. Avoid ignoring the root cause; you must find and remove the dropper executable, or the DNS settings will be hijacked again upon reboot.

References & External Analysis

• Search "dnschanger" on VirusTotal (External Analysis)

Frequently Asked Questions

Related Families (Category: trojan)

Explore other malware families in the same category:

• Mekotio
• Installmate
• Xxybwe
• Monitoringtool
• Prorat

Machine-readable

Get this profile as JSON: https://jordanricky1604-ship-it.github.io/malware-families-catalog/api/dnschanger.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.