Explorerhijack

Overview

ExplorerHijack (monitored under behavioral detection signatures including Behavior:Win32/ExplorerHijack, Trojan:Win32/ExplorerHijack, and HackTool:Win32/ExplorerHijack) is a specialized class of Windows trojans and memory injection tools active since 2014. Rather than operating as an isolated binary, ExplorerHijack specifically targets the core Windows shell process (explorer.exe) using advanced process injection, reflective DLL loading, and process hollowing techniques. Because explorer.exe is a universally trusted, persistent operating system component with default network communications and high privileges, malware that injects into explorer.exe effectively cloaks outbound command-and-control beacons, bypasses host-based application firewalls, and eludes static disk-based security scans. ExplorerHijack payloads use native Windows APIs—including VirtualAllocEx, WriteProcessMemory, and CreateRemoteThread—to allocate and execute shellcode within the address space of explorer.exe, subsequently deleting the initial on-disk dropper to maintain a pure in-memory footprint while executing secondary ransomware precursors, information stealers, or banking trojans.

Known aliases

Threat reports may refer to this family under multiple names:

• Behavior:Win32/ExplorerHijack
• Trojan:Win32/ExplorerHijack
• HackTool:Win32/ExplorerHijack
• ProcessHijack.Explorer

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 Techniques · Dll Injection Frameworks

Known Derivatives & Downstream Variants: Explorerhijack.A · Explorerinject.B

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.

• 9a0b1c2d3e4f5a6b7c8d9e0f1a2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f9a0b
• 0b1c2d3e4f5a6b7c8d9e0f1a2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f9a0b1c

Delivery vectors

• Secondary payload execution via weaponized Office macros and exploit kits
• Trojanized utility droppers self-deleting after injection

Persistence mechanisms

• Memory-resident threads inside explorer.exe
• HKCU\Software\Microsoft\Windows\CurrentVersion\Run\ExplorerSync

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_EXPLORERHIJACK_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Explorerhijack"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "explorerhijack" ascii wide nocase
        $s2 = "behavior:win32/explorerhijack" ascii wide nocase
        $s3 = "trojan:win32/explorerhijack" ascii wide nocase
        $s4 = "hacktool:win32/explorerhijack" ascii wide nocase
        $s5 = "processhijack.explorer" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Explorerhijack (Trojan) Execution & Triage
id: 99dd19cc-5ee3-592d-87c8-5804d36d9b86
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Explorerhijack 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/explorerhijack
- 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_001
- attack.t1055_002
- attack.t1055
- attack.t1106
- attack.t1562_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_EXPLORERHIJACK_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Explorerhijack 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 = "explorerhijack" 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. Immediately isolate the affected endpoint from all internal and external networks to contain C2 communications.
2. Do NOT restart the endpoint or terminate explorer.exe immediately; capture a volatile RAM dump to preserve injected modules.
3. Utilize EDR memory inspection tools to identify unmapped or executable memory pages within the explorer.exe process context.
4. Trace the parent process and disk execution artifacts to determine the initial vector that launched the injection dropper.

What to Avoid

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

1. Do not kill the explorer.exe process before capturing a forensic memory image, as this destroys volatile payload evidence.
2. Avoid relying only on standard file antivirus scans, as the primary payload is memory-resident and may have self-deleted on disk.

References & External Analysis

• Microsoft Defender Security Intelligence - Behavior:Win32/ExplorerHijack
• MITRE ATT&CK - Process Injection (T1055)
• Search "explorerhijack" on VirusTotal (External Analysis)
• Search "explorerhijack" on Any.Run (Sandbox Sandbox)
• Search "explorerhijack" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Trojan)

Explore other documented threats in the same operational category:

• Anyprotect
• Dostre
• Netpass
• Remoxec
• Terabit_Virus_Maker
• Bolik
• Sbdld
• Extenbro

Machine-readable

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