Sphinx
Table of Contents
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 our technical analysis hubs and the official MITRE ATT&CK framework:
| Technique | Name | Tactic | Official Spec |
|---|---|---|---|
T1185 | Browser Session Hijacking (Man-in-the-Browser web injects) | Collection | ATT&CK ↗ |
T1055 | Process Injection (Injecting into browser processes to steal data) | Defense Evasion | ATT&CK ↗ |
T1111 | Two-Factor Authentication Interception (Stealing session cookies to bypass 2FA) | Credential Access | ATT&CK ↗ |
T1056.001 | Input Capture: Keylogging | Collection | ATT&CK ↗ |
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):
| D3FEND ID | Countermeasure Name | Tactic | Countered ATT&CK | Defensive Guidance |
|---|---|---|---|---|
D3-PIAD | Process Injection Analysis & Detection | Detect | T1055 | Monitor cross-process thread creation (CreateRemoteThread) and asynchronous procedure calls (QueueUserAPC). |
D3-MFA | Multi-factor Authentication | Harden | T1056.001 | Enforce FIDO2 / WebAuthn physical tokens to render keystroke-intercepted passwords useless. |
D3-MitBA | Man-in-the-Browser Analysis | Detect | T1185 | Deploy browser extension whitelisting and hardware-backed session binding to prevent rogue DOM and socket injection. |
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:
Tier 1 Primitive Artifact Rule (Fast Triage)
Matches raw strings and file markers. Vulnerable to binary repacking and simple obfuscation.
rule MALWARE_WIN_SPHINX_T1_ARTIFACT {
meta:
description = "Tier 1 Primitive Artifact: Raw string matches for Sphinx"
tier = "T1 - Primitive Artifact"
confidence = "Low-Medium (Fast Triage)"
author = "SystemHelpdesk Threat Research Desk"
date = "2026-10-14"
strings:
$s1 = "sphinx" ascii wide nocase
condition:
uint16(0) == 0x5a4d and any of them
}Tier 2 Behavioral Context Rule (Process Chains & Sigma)
Tracks parent-child process anomalies and suspicious scripting telemetry. Resilient against file renames.
title: SystemHelpDesk Detection - Sphinx (Trojan) Execution & Triage
id: 1f7ff3fb-7065-5ac6-a8ea-129845bd8f33
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
with the Sphinx 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/sphinx
- 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.t1111
- attack.t1056_001
- attack.t1055
- attack.t1185
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: mediumTier 3 Attribution Fingerprint Rule (High Fidelity)
Deep signature matching distinctive operational fingerprints and payload characteristics.
rule MALWARE_WIN_SPHINX_T3_ATTRIBUTION {
meta:
description = "Tier 3 Attribution Fingerprint: Heuristic detection for Sphinx 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 = "sphinx" 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.
- Immediately isolate the infected endpoint to halt the active exfiltration of banking credentials and session cookies.
- Mandate an immediate password reset for the compromised user, prioritizing banking, cryptocurrency, and corporate SSO accounts.
- Force a session token revocation (log out of all active sessions) for the user across all critical SaaS applications and internal portals.
- 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.
- Do not trust that 2FA will protect the user's accounts; Sphinx steals active session cookies, which bypasses the need for 2FA.
- 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)
- Search "sphinx" on Any.Run (Sandbox Sandbox)
- Search "sphinx" on MalwareBazaar (Malware Samples)
Frequently Asked Questions
What is Sphinx and what threat category does it belong to?
Sphinx is classified as a Trojan. Documented across security telemetry, it is engineered to execute unauthorized operations, establish persistent footholds on target endpoints, and facilitate malicious campaigns targeting enterprise and individual environments.
How does Sphinx establish persistence and evade defensive controls?
Sphinx typically establishes persistence through registry run keys, scheduled tasks, or service installations, while evading signature-based antivirus solutions through code obfuscation, memory injection, or anti-analysis sandbox checks.
What are the essential incident response steps for mitigating a Sphinx compromise?
Security teams responding to Sphinx should immediately isolate affected endpoints from the network, perform memory triage to capture volatile forensic artifacts, audit registry and startup persistence mechanisms, revoke exposed user credentials, and restore systems from verified, clean backups.
What secondary payloads and staging behaviors are commonly associated with Sphinx?
Sphinx frequently operates as a loader or dropper designed to establish a foothold before downloading and executing secondary high-impact malware payloads. Depending on the threat actor's objectives, these dropped modules can range from ransomware and banking injects to modular infostealers and remote management backdoors.
How can security operations teams effectively detect and hunt for Sphinx across enterprise endpoints?
Defenders should hunt for Sphinx by deploying behavioral endpoint detection and response (EDR) rules that monitor suspicious process spawning (such as cmd.exe or powershell.exe spawned from office documents or temporary directories), anomalous outbound network connections from non-browser binaries, and unauthorized modifications to Windows Run keys and scheduled task registries.
How do I remove the Sphinx Trojan from Windows?
Manual removal of Sphinx 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 Sphinx a virus or a Trojan?
Sphinx is classified as a Trojan. Unlike traditional viruses that infect files, modern malware like Sphinx typically operates as a standalone payload designed to compromise systems, steal data, or deploy secondary stage implants.
What are the main symptoms of a Sphinx infection?
Symptoms of Sphinx 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.
Protect Your Network Against Trojans
Want to prevent Sphinx and similar threats from compromising your organization? Read our comprehensive defensive guide: Banking Trojan Protection for Businesses.
📣 Threat Intel Correction or Update?
Notice an outdated IOC, unlisted alias, or disputed attribution? Threat researchers are invited to propose an update on GitHub or contact the SystemHelpDesk research desk. All community revisions are credited in our public CHANGELOG.
Machine-readable
Get this profile as JSON: https://malware-families-catalog.systemhelpdesk.com/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.