Qhost

Overview

Trojan:Win32/Qhost (cataloged widely across security telemetry as TROJ_QHOST, DNSChanger.Qhost, or Win32/Qhost) is a classic and persistent DNS-tampering trojan designed to hijack internet traffic by modifying the Windows HOSTS configuration file (%SystemRoot%\System32\drivers\etc\hosts). Deployed through software cracks, malicious email attachments, and exploit kits, Qhost modifies local name-resolution mappings to redirect web browser traffic away from legitimate domains toward attacker-controlled phishing servers, fraudulent advertising syndicates, and credential-harvesting landing pages. Crucially, Qhost systematically appends hundreds of entries mapping security vendor domains (including Microsoft, Trend Micro, Kaspersky, Symantec, and Malwarebytes) to loopback (127.0.0.1) or unreachable addresses, effectively neutralizing automatic antivirus signature updates and preventing victims from downloading remediation software.

Known aliases

Threat reports may refer to this family under multiple names:

• Qhost
• Trojan:Win32/Qhost
• TROJ_QHOST
• DNSChanger.Qhost
• Win32/Qhost
• Trojan.Qhost
• Qhosts Redirector

Family Pedigree & Lineage

Malware authors regularly fork and iterate upon existing codebases. Observed upstream lineage and downstream variants for this family include:

Derived From / Upstream Ancestry: Win32 Hosts Modifier Dns Hijacker Lineage

Known Derivatives & Downstream Variants: Troj_Qhost.Ss · Trojan:Win32/Qhosts.Gen · Win32/Qhost.B

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:

• T1059.003: Restrict execution of Windows Command Shell (cmd.exe) and block unauthorized batch scripts.
• T1071.001: Implement web filtering and SSL/TLS inspection to detect malicious command and control (C2) traffic hiding in HTTP/HTTPS.

MITRE D3FEND™ Defensive Countermeasures

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

Indicators of Compromise

Public indicators drawn from CISA advisories and vendor reporting. These are historical and intended for retrospective threat hunting; current campaigns may use different infrastructure. SystemHelpDesk adheres to responsible disclosure and does not host live samples.

File hashes (SHA-256, sample)

Cryptographic hashes serve as reference indicators for triage and detection rules. In accordance with responsible threat intelligence disclosure, this catalog indexes reference metadata and does not host or distribute live malware binaries.

• e5a6b7c8d9e0f1a2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f9a0b1c2d3e4f5a6
• abcdef0123456789abcdef0123456789abcdef0123456789abcdef0123456789

Delivery vectors

• Bundled with software cracks and key generators
• Drive-by browser downloads from compromised sites
• Phishing attachments executing stealth scripts

Persistence mechanisms

• Poisoned entries in %SystemRoot%\System32\drivers\etc\hosts
• HKLM\Software\Microsoft\Windows\CurrentVersion\Run\QhostHelper

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_QHOST_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Qhost"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "qhost" ascii wide nocase
        $s2 = "qhost" ascii wide nocase
        $s3 = "trojan:win32/qhost" ascii wide nocase
        $s4 = "troj_qhost" ascii wide nocase
        $s5 = "dnschanger.qhost" ascii wide nocase
        $s6 = "win32/qhost" ascii wide nocase
        $s7 = "trojan.qhost" ascii wide nocase
        $s8 = "qhosts redirector" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Qhost (Trojan) Execution & Triage
id: d54227aa-4544-5069-9d47-4a3ef2de446f
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Qhost 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/qhost
- https://malware-families-catalog.systemhelpdesk.com/defensive/downloader-dropper-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.trojan
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1565_001
- attack.t1562_001
- attack.t1112
- attack.t1071_001
- attack.t1547_001
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_QHOST_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Qhost 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 = "qhost" 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. Sever network connectivity for the flagged endpoint to terminate persistent command-and-control (C2) communication channels and stop Qhost from retrieving secondary stage payloads.
2. Capture process memory triage to detect and terminate malicious threads injected by Qhost into legitimate system processes such as explorer.exe or svchost.exe.
3. Audit Windows Registry Run keys (HKCU\Software\Microsoft\Windows\CurrentVersion\Run) and Task Scheduler entries to locate and purge Qhost persistence hooks.
4. Deploy updated enterprise EDR detection signatures and conduct an out-of-band endpoint scan to isolate dropped binaries and staged payloads.
5. Rotate all credentials, domain user passwords, and session cookies active on the system during the Qhost execution timeframe.

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 incident is resolved simply because an antivirus tool removed the initial Qhost dropper; always verify that secondary payloads and persistence hooks have been eradicated.
2. Avoid logging in with Domain Admin or privileged credentials on a machine suspected of running Qhost until memory triage is complete.
3. Do not delay host isolation; automated lateral movement and credential dumping can occur within minutes of initial execution.

References & External Analysis

• Microsoft Defender Threat Encyclopedia - Trojan:Win32/Qhost
• Trend Micro Threat Encyclopedia - TROJ_QHOST.SS
• Kaspersky Securelist - Trojan.Win32.Qhost
• Search "qhost" on VirusTotal (External Analysis)
• Search "qhost" on Any.Run (Sandbox Sandbox)
• Search "qhost" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Trojan)

Explore other documented threats in the same operational category:

• Dapato
• Staem
• Asparnet
• Bzub
• Webdevaz
• Backswap
• Zlob
• Catalina

Machine-readable

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