Cridex

Overview

Executive Summary

Infection Vector and Technical Capabilities

• Web Injection (Man-in-the-Browser): Cridex's primary weapon was its ability to inject malicious HTML and JavaScript directly into the user's web browser in real-time (MitB). When a victim visited a targeted banking portal, Cridex would alter the login page, requesting additional sensitive information (like ATM PINs or mother's maiden name) and bypassing two-factor authentication.
• Worm Propagation: Unlike modern banking trojans, Cridex actively sought to spread. It monitored the system for newly inserted USB flash drives, copying itself and creating an `AutoRun.inf` file. It also attempted to spread across open SMB network shares using weak or stolen credentials.
• Peer-to-Peer (P2P) Architecture: Later variants of Cridex experimented with a P2P command-and-control (C2) architecture. Instead of relying on a centralized server that could be easily taken down, infected nodes communicated with each other to distribute configuration files and exfiltrate stolen data.

Threat Assessment

Remediation and Eradication

• Immediate Network Segmentation: Physically or logically segment the infected endpoint and its surrounding VLAN to halt the lateral spread of the worm via SMB shares.
• Credential Reset and Fraud Alert: All financial institutions accessed from the infected machine must be notified immediately. All session tokens and credentials must be revoked and reset.
• Disable AutoRun: Ensure enterprise-wide Group Policy Objects (GPOs) completely disable AutoRun and AutoPlay to prevent the USB propagation vector.

Known aliases

Threat reports may refer to this family under multiple names:

• Worm.Cridex
• Trojan.Cridex
• W32/Cridex

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:

• T1056.004: Monitor for unauthorized keylogging, screen capturing, or web browser API hooking. Deploy EDR to detect API hooking.
• T1185: Enforce strong MFA and use browser isolation or hardened browsers for sensitive financial or administrative portals to defeat session hijacking.
• T1566.001: Scan email attachments for malicious macros, scripts, or suspicious archive files.

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_CRIDEX_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Cridex"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "cridex" ascii wide nocase
        $s2 = "worm.cridex" ascii wide nocase
        $s3 = "trojan.cridex" ascii wide nocase
        $s4 = "w32/cridex" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Cridex (Trojan) Execution & Triage
id: 70bab344-336d-54f7-a5ff-de6512052e2e
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Cridex 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/cridex
- 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.t1056_004
- attack.t1091
- attack.t1185
- attack.t1566_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_CRIDEX_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Cridex 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 = "cridex" 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 Cridex from retrieving secondary stage payloads.
2. Capture process memory triage to detect and terminate malicious threads injected by Cridex 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 Cridex 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 Cridex 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 Cridex 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 Cridex 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 "cridex" on VirusTotal (External Analysis)
• Search "cridex" on Any.Run (Sandbox Sandbox)
• Search "cridex" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Trojan)

Explore other documented threats in the same operational category:

• Smshoax
• Addlyrics
• Alinaos
• Admedia
• Aauto
• Autit
• Bnksa
• Polypatch

Machine-readable

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