Hijacker

Overview

Hijacker (cataloged across security vendors as BrowserModifier:Win32/Hijacker, Adware:Win32/Hijacker, and Trojan:Win32/Hijacker) is a widespread family of persistent browser manipulation programs and adware frameworks active since 2013. Designed to monetize web browsing sessions without user consent, Hijacker is distributed through pay-per-install software bundlers, fake software update prompts, and malicious browser extension marketplaces. Once executed on Windows, Hijacker makes deep modifications to browser preferences across Google Chrome, Mozilla Firefox, and Microsoft Edge. It forcibly alters default search engines, new tab pages, and start pages to redirect queries through affiliate monetization hubs. To prevent remediation, Hijacker modifies Windows Registry Group Policies (such as ExtensionInstallForcelist and HomepageLocation), displaying 'Managed by your organization' within Chrome to block user uninstall attempts. In addition to search hijacking, Hijacker injects banner advertisements into websites and monitors search queries and visited URLs to harvest tracking telemetry.

Known aliases

Threat reports may refer to this family under multiple names:

• BrowserModifier:Win32/Hijacker
• Adware:Win32/Hijacker
• Trojan:Win32/Hijacker
• Win32/Hijacker

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: Commercial Browser Hijackers

Known Derivatives & Downstream Variants: Hijacker.A · Hijacker.Searchmodifier

MITRE ATT&CK Techniques

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

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.

• 1c0d9e8f7a6b5c4d3e2f1a0b9c8d7e6f5a4b3c2d1e0f9a8b7c6d5e4f3a2b1c0d
• 6d5e4f3a2b1c0d9e8f7a6b5c4d3e2f1a0b9c8d7e6f5a4b3c2d1e0f9a8b7c6d5e

Delivery vectors

• chrome_setup_update.exe
• search_assistant.exe

Persistence mechanisms

• HKLM\Software\Policies\Google\Chrome\ExtensionInstallForcelist
• HKCU\Software\Microsoft\Windows\CurrentVersion\Run\SearchEnhancer

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_HIJACKER_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Hijacker"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "hijacker" ascii wide nocase
        $s2 = "browsermodifier:win32/hijacker" ascii wide nocase
        $s3 = "adware:win32/hijacker" ascii wide nocase
        $s4 = "trojan:win32/hijacker" ascii wide nocase
        $s5 = "win32/hijacker" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Hijacker (Adware) Execution & Triage
id: 2a672672-855f-5578-bbc3-94df827db2ed
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Hijacker 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/hijacker
- 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.adware
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1566_002
- attack.t1189
- attack.t1547_001
- attack.t1176
- attack.t1112
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_HIJACKER_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Hijacker 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 = "hijacker" 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. Audit Windows Group Policies and the Registry to remove any forced extension installation policies created by the hijacker.
3. Deploy an enterprise adware removal tool (e.g., AdwCleaner) to locate and strip the deeply embedded registry hooks and watchdog services.
4. Check all browser desktop shortcuts (Right Click -> Properties) and remove any malicious URLs appended to the 'Target' field.

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 native 'remove extension' button; Hijackers are explicitly designed to bypass or disable this functionality.
2. Avoid ignoring the infection; the tracking infrastructure actively harvests browsing habits, which may include access to sensitive portals.

References & External Analysis

• Microsoft Defender Security Intelligence - BrowserModifier:Win32/Hijacker
• Malwarebytes Labs - Browser Hijacker Removal Guide
• Search "hijacker" on VirusTotal (External Analysis)
• Search "hijacker" on Any.Run (Sandbox Sandbox)
• Search "hijacker" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Adware)

Explore other documented threats in the same operational category:

• Downloadassistant
• Perion
• Conduit
• Xetapp
• Ibryte
• Vkontaktedj
• Spigot
• Autofixerpro

Machine-readable

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