Dnscleaner

Overview

DNSCleaner (classified across security vendors as PUA:Win32/DNSCleaner and Rogue:Win32/DNSCleaner) is a scareware system optimizer and Potentially Unwanted Application that deceives users regarding the safety and performance of their Windows network configuration. Installed via third-party software bundles or misleading browser alerts, DNSCleaner initiates automated scans that falsely claim the user's DNS cache, hosts file, and network registry keys are severely corrupted or hijacked by malware. It presents alarming full-screen warnings coercing the user to buy a paid software activation key to repair the DNS settings, while writing persistence entries to HKCU\Software\Microsoft\Windows\CurrentVersion\Run and installing background telemetry services.

Known aliases

Threat reports may refer to this family under multiple names:

• PUA:Win32/DNSCleaner
• Rogue:Win32/DNSCleaner
• Program:Win32/DNSCleaner
• DNSCleaner Utility
• Win32/DNSCleaner

MITRE ATT&CK Techniques

Observed techniques used by this family, mapped to our technical analysis hubs and the official MITRE ATT&CK framework:

Tactical Mitigations

Based on the techniques used by this family, consider the following defensive strategies:

• T1105: Implement network intrusion detection systems (NIDS) and host-based firewalls to block unauthorized inbound or outbound file transfers.

MITRE D3FEND™ Defensive Countermeasures

Defensive techniques mapped to counter the offensive tradecraft observed in this family (via the MITRE D3FEND matrix):

Tiered Detection Rules (Cisco CAIRN Model)

Modern threat detection requires multi-layered rule engineering. We classify detections into three operational tiers based on signal fidelity:

rule MALWARE_WIN_DNSCLEANER_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Dnscleaner"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "dnscleaner" ascii wide nocase
        $s2 = "pua:win32/dnscleaner" ascii wide nocase
        $s3 = "rogue:win32/dnscleaner" ascii wide nocase
        $s4 = "program:win32/dnscleaner" ascii wide nocase
        $s5 = "dnscleaner utility" ascii wide nocase
        $s6 = "win32/dnscleaner" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Dnscleaner (Pua) Execution & Triage
id: 73e1dc3e-0d93-5440-99b5-bd22ff01a13b
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Dnscleaner malware family. Detects suspicious execution from temporary
  user directories with hidden window flags and background transfer utilities.
references:
- https://malware-families-catalog.systemhelpdesk.com/families/dnscleaner
- https://malware-families-catalog.systemhelpdesk.com/defensive/ransomware-protection
- https://malware-families-catalog.systemhelpdesk.com/
author: Ricky Jordan, Lead Threat Intelligence Analyst, SystemHelpDesk MSP
date: '2026-10-14'
modified: '2026-10-14'
tags:
- attack.pua
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1491
- attack.t1547_001
- attack.t1053_005
- attack.t1112
- attack.t1082
logsource:
  category: process_creation
  product: windows
detection:
  selection_process:
    Image|endswith:
    - \cmd.exe
    - \powershell.exe
    - \cscript.exe
    - \wscript.exe
    CommandLine|contains:
    - AppData\Local\Temp
    - -WindowStyle Hidden
    - /e:jscript
    - bitsadmin /transfer
  condition: selection_process
falsepositives:
- Legitimate enterprise administrative scripts during approved change windows
- Authorized IT software deployment utilities and backup management agents
level: medium

rule MALWARE_WIN_DNSCLEANER_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Dnscleaner tradecraft"
        tier = "T3 - Attribution Fingerprint"
        confidence = "High (Confirmed Family Signature)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        // Core family identifier & heuristic payload signatures
        $attrib_str = "dnscleaner" ascii wide nocase
        $pe_magic = "MZ" ascii
        $net_marker = "http" ascii nocase
    condition:
        uint16(0) == 0x5a4d and ($attrib_str and $net_marker) and filesize < 15MB
}

Containment & Response Steps

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

1. Quarantine the endpoint to halt the active exfiltration of browsing telemetry and the downloading of further adware modules.
2. Check and reset the Windows network adapter's DNS settings (IPv4) to ensure they are pointing to legitimate corporate or ISP servers.
3. Deploy an enterprise adware removal tool (e.g., AdwCleaner) to locate and strip the deeply embedded registry hooks and watchdog services.
4. Force a complete reset of all installed web browsers to factory defaults to eradicate the rogue extensions and restore the homepage.

What to Avoid

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

1. Do not rely solely on the browser's 'remove extension' button; Dnscleaner frequently uses GPOs and watchdog services to immediately reinstall itself.
2. Avoid ignoring the infection; adware tracking data is highly detailed and may expose corporate activities or access to internal portals.

References & External Analysis

• Microsoft Defender Threat Encyclopedia - PUA:Win32/DNSCleaner
• Trend Micro Security Research - PUA.Win32.DNSCleaner Analysis
• MITRE ATT&CK - Defacement: Displaying Fake Security Alerts (T1491)
• Search "dnscleaner" on VirusTotal (External Analysis)
• Search "dnscleaner" on Any.Run (Sandbox Sandbox)
• Search "dnscleaner" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Pua)

Explore other documented threats in the same operational category:

• Gamemodding
• Filetour
• Presenoker
• Cloudguard
• Deceptpcclean
• Appset
• Systweak
• Downloadadmin

Machine-readable

Get this profile as JSON: https://malware-families-catalog.systemhelpdesk.com/api/dnscleaner.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.