Sphinx

Overview

Trojan:Win32/Sphinx is a sophisticated Info-Stealer and banking trojan, highly active in targeting financial institutions and cryptocurrency platforms. While it shares some conceptual similarities with older trojans like Zeus, Sphinx operates as a modern, evasive data harvesting tool. It focuses on stealing credentials, session cookies, and financial data by injecting malicious code directly into the user's web browser, effectively performing Man-in-the-Browser (MitB) attacks.

Understanding Sphinx (Info-Stealers)
To an end-user, the infection is entirely invisible. They log into their bank normally, unaware that Sphinx is silently intercepting their keystrokes and modifying the web page to request additional, fraudulent information (like ATM PINs). For a security analyst, a Sphinx infection represents a critical, immediate breach of highly sensitive credentials and requires a rapid response to prevent financial fraud (`T1111`).

Execution and Espionage Mechanics
Sphinx is predominantly distributed through highly targeted malspam campaigns (`T1566.001`), often using weaponized Office documents. Upon execution, Sphinx establishes persistence (typically via Registry Run keys - `T1547.001`) and aggressively injects its core DLL payload into running browser processes (like `chrome.exe` or `firefox.exe`) using advanced process hollowing or atom bombing techniques (`T1055`). Once injected, it intercepts API calls related to network communication, allowing it to read all HTTPS traffic in cleartext. It captures login credentials (`T1056.001`), scrapes session cookies (`T1539`), and actively injects fraudulent HTML forms into targeted banking portals (Web Injects - `T1185`).

Indicators of Compromise & Impact
The impact is immediate, devastating financial fraud and credential theft. Host-based IoCs include EDR alerts for 'Suspicious Process Injection' specifically targeting browser executables. The creation of unexpected, randomly named DLLs in the `%AppData%` directory is common. Network IoCs involve the malware beaconing to C2 servers using custom, often encrypted protocols over port 80/443 to receive updated 'web inject' configuration files and to exfiltrate stolen data.

MITRE ATT&CK Techniques

Observed techniques used by this family, mapped to the 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.

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_SPHINX {
    meta:
        description = "Detects Sphinx (trojan)"
        author = "SystemHelpdesk Boilerplate Generator"
        date = "2026-07-06"
    strings:
        $s1 = "sphinx" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

Sigma Rule

title: Suspicious Sphinx Activity
id: 4a2c09ffbc6e7d0414d1ae731e3a0ce5
status: experimental
description: Detects generic indicators of the sphinx malware family.
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith:
            - '\cmd.exe'
            - '\powershell.exe'
        CommandLine|contains:
            - "*sphinx*"
    condition: selection
level: medium

Containment & Response Steps

Ordered checklist for responders. Adapt to your environment and engage professional support for active incidents.

1. Immediately isolate the infected endpoint to halt the active exfiltration of banking credentials and session cookies.
2. Mandate an immediate password reset for the compromised user, prioritizing banking, cryptocurrency, and corporate SSO accounts.
3. Force a session token revocation (log out of all active sessions) for the user across all critical SaaS applications and internal portals.
4. Analyze EDR telemetry to identify the initial infection vector (e.g., the specific phishing email) to protect other users.

What to Avoid

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

1. Do not trust that 2FA will protect the user's accounts; Sphinx steals active session cookies, which bypasses the need for 2FA.
2. Avoid relying solely on manual file deletion; the injected browser processes must be terminated, and the persistence mechanisms removed.

References & External Analysis

• Search "sphinx" on VirusTotal (External Analysis)

Frequently Asked Questions

Related Families (Category: trojan)

Explore other malware families in the same category:

• Diskwriter
• Krilog
• Arkeistealer
• Mansabo
• Gamania

Machine-readable

Get this profile as JSON: https://jordan123234-malware-families-explorer.static.hf.space/api/sphinx.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.