Processhijack

Overview

ProcessHijack (cataloged in threat telemetry as Trojan:Win32/ProcessHijack and Trojan:Win32/ProcessHijack.GTM!MTB) represents a family of sophisticated stealth trojans and process-injection tools identified by Microsoft Defender in 2018. Designed primarily for defense evasion, ProcessHijack abuses legitimate Windows operating system processes (such as svchost.exe, explorer.exe, or msbuild.exe) by utilizing advanced process hollowing, reflective DLL loading, and asynchronous procedure call (APC) injection techniques. Upon launching from a dropper or malicious document, ProcessHijack hollows out a benign system binary in memory, replaces its executable image with encrypted malicious payload code, and executes under the trusted process context. This subversion allows the malware to bypass endpoint application whitelisting and traditional host intrusion prevention systems (HIPS). Once embedded, ProcessHijack establishes encrypted C2 beaconing, logs user activity, and provides threat actors with an stealthy in-memory backdoor.

Known aliases

Threat reports may refer to this family under multiple names:

• Trojan:Win32/ProcessHijack
• Trojan:Win32/ProcessHijack.GTM!MTB
• Win32/ProcessHijack
• Trojan.ProcessHijack

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: Process Hollowing / Memory Injection Framework · Stealth In-Memory Loader Architecture

Known Derivatives & Downstream Variants: Processhijack.A · Processhijack.Gtm · Processhijack.Gen

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:

• 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.

• a3b5c7d9e1f3a5b7c9d1e3f5a7b9c1d3e5f7a9b1c3d5e7f9a1b3c5d7e9f1a3b5
• b4c6d8e0f2a4b6c8d0e2f4a6b8c0d2e4f6a8b0c2d4e6f8a0b2c4d6e8f0a2b4c6

Delivery vectors

• Phishing emails delivering macro-enabled documents or weaponized shortcut (.lnk) loaders
• Secondary payload dropping via compromised initial access brokers

Persistence mechanisms

• HKCU\Software\Microsoft\Windows\CurrentVersion\Run\ProcessHelper
• %LOCALAPPDATA%\SystemUtils\hijack_loader.exe

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_PROCESSHIJACK_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Processhijack"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "processhijack" ascii wide nocase
        $s2 = "trojan:win32/processhijack" ascii wide nocase
        $s3 = "trojan:win32/processhijack.gtm!mtb" ascii wide nocase
        $s4 = "win32/processhijack" ascii wide nocase
        $s5 = "trojan.processhijack" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Processhijack (Trojan) Execution & Triage
id: 0b3c5be9-94a1-5a18-b0b7-9c6a46468b2b
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Processhijack 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/processhijack
- 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.t1055_012
- attack.t1055_001
- attack.t1027
- 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_PROCESSHIJACK_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Processhijack 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 = "processhijack" 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. Isolate the compromised endpoint immediately to sever active in-memory C2 communication channels.
2. Perform a full memory dump of the infected machine to extract unencrypted payload binaries from hollowed processes.
3. Terminate corrupted parent and hollowed child processes using an endpoint detection and response (EDR) agent.
4. Audit scheduled tasks, registry autostart keys, and WMI event subscriptions to eliminate persistence mechanisms.

What to Avoid

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

1. Do not rely exclusively on traditional file-on-disk antivirus scanning, as process hollowing executes entirely within memory.
2. Avoid allowing unmonitored execution of administrative utilities (such as msbuild or powershell) on non-developer endpoints.

References & External Analysis

• Microsoft Defender Security Intelligence - Trojan:Win32/ProcessHijack.GTM!MTB
• MITRE ATT&CK - Technique T1055: Process Injection
• Search "processhijack" on VirusTotal (External Analysis)
• Search "processhijack" on Any.Run (Sandbox Sandbox)
• Search "processhijack" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Trojan)

Explore other documented threats in the same operational category:

• Multiinjector
• Mmnfbgfpueki
• Fakesmoke
• Netdevil
• Aenjaris
• Bubbledock
• Xxybuj
• Vampire

Machine-readable

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