Firehooker

Overview

Executive Summary

Infection Vector and Technical Capabilities

• Advanced API Hooking (MitB): Instead of relying on a simple, noisy global keylogger, Firehooker injects malicious DLLs directly into the active browser process (e.g., `firefox.exe`, `chrome.exe`). It hooks specific cryptographic and network APIs (like `PR_Write` or `HttpSendRequest`). This allows the malware to capture passwords and credit card numbers *before* they are encrypted via HTTPS/SSL.
• Form Grabbing and Web Injects: Because it sits inside the browser, Firehooker can perform "form grabbing"—stealing data submitted in HTML forms. Advanced variants can dynamically inject malicious HTML fields into legitimate banking websites (e.g., asking for an ATM PIN) to steal additional 2FA data.
• Data Exfiltration: All intercepted data is compiled, encrypted, and exfiltrated via HTTP POST requests to an attacker-controlled command-and-control (C2) server.

Threat Assessment

Incident Response and Remediation

• Global Credential Reset: ALL credentials entered on the compromised machine while infected—especially banking passwords, corporate VPN logins, and webmail access—must be considered compromised and reset immediately from a *different, clean device*.
• MFA Token Revocation: Assume session cookies were stolen. Force an immediate sign-out of all active sessions for critical web applications to invalidate the stolen tokens.
• Endpoint Eradication: The sophisticated process injection techniques used by Firehooker necessitate a full forensic review. Re-imaging the machine from a trusted baseline is required to ensure complete eradication and that no hidden hooks remain in the system.

Known aliases

Threat reports may refer to this family under multiple names:

• Trojan.Firehooker
• PWS.Firehooker
• Banker.Hooker

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:

• T1056.001: Implement Endpoint Detection and Response (EDR) to monitor for suspicious API calls related to keystroke interception. Enforce Multi-Factor Authentication (MFA) to render stolen passwords useless.
• T1185: Enforce strong MFA and use browser isolation or hardened browsers for sensitive financial or administrative portals to defeat session hijacking.

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_FIREHOOKER_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Firehooker"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "firehooker" ascii wide nocase
        $s2 = "trojan.firehooker" ascii wide nocase
        $s3 = "pws.firehooker" ascii wide nocase
        $s4 = "banker.hooker" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Firehooker (Trojan) Execution & Triage
id: cb50d9f5-2fea-5528-966b-2b7b6d45e859
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Firehooker 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/firehooker
- 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.t1185
- attack.t1056_001
- attack.t1189
- attack.t1555_003
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_FIREHOOKER_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Firehooker 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 = "firehooker" 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 Firehooker from retrieving secondary stage payloads.
2. Capture process memory triage to detect and terminate malicious threads injected by Firehooker 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 Firehooker 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 Firehooker 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 Firehooker 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 Firehooker 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

• Search "firehooker" on VirusTotal (External Analysis)
• Search "firehooker" on Any.Run (Sandbox Sandbox)
• Search "firehooker" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Trojan)

Explore other documented threats in the same operational category:

• Tpyn
• Regrun
• Messengerpass
• Fsysna
• Xxybzx
• Sphinx
• Dexel
• Yoddos

Machine-readable

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