Firehooker
Overview
Executive Summary
Firehooker is a highly specialized Information Stealer (Info-Stealer) designed specifically to target web browsers, with a historical focus on Mozilla Firefox (hence the name). Its primary objective is to execute a "man-in-the-browser" (MitB) attack by hooking into the browser's core API functions, allowing threat actors to intercept, record, and steal sensitive credentials, session tokens, and financial data in real-time as the user types them.Infection Vector and Technical Capabilities
Firehooker is typically distributed as a secondary payload, dropped onto a system by an initial access broker, a downloader trojan, or via an exploit kit originating from a compromised website. Upon execution, Firehooker performs advanced, targeted espionage:- 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
A Firehooker infection is a critical security incident. Because it operates via API hooking within the browser, the data theft is invisible to the user; the padlock icon still shows a secure HTTPS connection. The stolen session tokens and credentials can be immediately used to execute fraudulent financial transactions or access secure corporate portals.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:
MITRE ATT&CK Techniques
This family has been observed using the following ATT&CK techniques: T1185 T1056.001 T1189 T1555.003
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.
Generated Detections (Boilerplate)
These YARA and Sigma rules are auto-generated based on the family name and aliases. They must be heavily tuned before deployment in a production environment.
YARA Rule
rule MALWARE_WIN_FIREHOOKER {
meta:
description = "Detects Firehooker (trojan)"
author = "SystemHelpdesk Boilerplate Generator"
date = "2026-07-06"
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
}Sigma Rule
title: Suspicious Firehooker Activity
id: 73adac1a894ef98c8b1603a65dbc829d
status: experimental
description: Detects generic indicators of the firehooker malware family.
logsource:
category: process_creation
product: windows
detection:
selection:
Image|endswith:
- '\cmd.exe'
- '\powershell.exe'
CommandLine|contains:
- "*firehooker*"
- "*trojan.firehooker*"
- "*pws.firehooker*"
- "*banker.hooker*"
condition: selection
level: mediumReferences & External Analysis
- Search "firehooker" on VirusTotal (External Analysis)
Frequently Asked Questions
How do I remove the Firehooker Trojan from Windows?
Manual removal of Firehooker is highly discouraged as it may leave persistence mechanisms intact. We recommend disconnecting the device from the internet and utilizing a professional incident response service or enterprise-grade EDR software to conduct a full forensic sweep.
Is Firehooker a virus or a Trojan?
Firehooker is classified as a Trojan. Unlike traditional viruses that infect files, modern malware like Firehooker typically operates as a standalone payload designed to compromise systems, steal data, or deploy secondary stage implants.
What are the main symptoms of a Firehooker infection?
Symptoms of Firehooker can include unexpected system slowness, unauthorized outbound network traffic to unknown IP addresses, disabled security software, and suspicious background processes running from AppData or Temp directories.
Related Families (Category: trojan)
Explore other malware families in the same category:
Protect Your Network Against Trojans
Want to prevent Firehooker and similar threats from compromising your organization? Read our comprehensive defensive guide: Banking Trojan Protection.
Machine-readable
Get this profile as JSON: https://jordanricky1604-ship-it.github.io/malware-families-catalog/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.