Orcus

Overview

Orcus RAT (cataloged across security vendors and threat intelligence databases as Backdoor:Win32/Orcus, MSIL/Orcus, and Orcus RAT) is a notorious, modular .NET remote access trojan first surfacing in 2016. Developed by German programmer Vincent Leo Griebel and marketed by Canadian citizen John Paul Revesz under the commercial front 'Orcus Technologies', the tool was ostensibly sold as a legitimate remote administration utility while being advertised and utilized extensively across cybercrime forums. Following an extensive international investigation, Canada's CRTC issued landmark penalties against Orcus Technologies for computer malware distribution. Architecturally, Orcus features an extensible C# plugin system, evasion routines that detect sandbox and virtual machine environments, and scheduled task persistence via 'Orcus Respawner'. Attackers utilize Orcus to log keystrokes, capture webcam footage, record audio, steal browser passwords and cryptocurrency wallets, and launch distributed denial-of-service (DDoS) attacks.

Known aliases

Threat reports may refer to this family under multiple names:

• Backdoor:Win32/Orcus
• MSIL/Orcus
• Orcus RAT
• Trojan:MSIL/Orcus

Family Pedigree & Lineage

Malware authors regularly fork and iterate upon existing codebases. Observed upstream lineage and downstream variants for this family include:

Derived From / Upstream Ancestry: Commercial .Net Remote Access Trojans

Known Derivatives & Downstream Variants: Orcus 1.9 · Orcus 2.0 · Orcus.Msil

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.
• T1071.001: Implement web filtering and SSL/TLS inspection to detect malicious command and control (C2) traffic hiding in HTTP/HTTPS.
• T1125: Restrict access to local camera or microphone APIs. Utilize endpoint protection that monitors hardware access.

MITRE D3FEND™ Defensive Countermeasures

Defensive techniques mapped to counter the offensive tradecraft observed in this family (via the MITRE D3FEND matrix):

Indicators of Compromise

Public indicators drawn from CISA advisories and vendor reporting. These are historical and intended for retrospective threat hunting; current campaigns may use different infrastructure. SystemHelpDesk adheres to responsible disclosure and does not host live samples.

File hashes (SHA-256, sample)

Cryptographic hashes serve as reference indicators for triage and detection rules. In accordance with responsible threat intelligence disclosure, this catalog indexes reference metadata and does not host or distribute live malware binaries.

• 9e0f1a2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f9a0b1c2d3e4f5a6b7c8d9e0f
• 0f1a2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f9a0b1c2d3e4f5a6b7c8d9e0f1a

Delivery vectors

• client_orcus.exe
• game_trainer.exe

Persistence mechanisms

• HKCU\Software\Microsoft\Windows\CurrentVersion\Run\Orcus
• %AppData%\Orcus\Orcus.exe

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_ORCUS_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Orcus"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "orcus" ascii wide nocase
        $s2 = "backdoor:win32/orcus" ascii wide nocase
        $s3 = "msil/orcus" ascii wide nocase
        $s4 = "orcus rat" ascii wide nocase
        $s5 = "trojan:msil/orcus" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Orcus (Backdoor) Execution & Triage
id: a3d9a82e-9541-5326-a53d-3997ce1b404d
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Orcus malware family. Detects proxy execution, reflective DLL loading,
  and remote command injection associated with modular enterprise backdoors.
references:
- https://malware-families-catalog.systemhelpdesk.com/families/orcus
- https://malware-families-catalog.systemhelpdesk.com/defensive/backdoor-rat-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.backdoor
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1056_001
- attack.t1113
- attack.t1125
- attack.t1053_005
- attack.t1555_003
logsource:
  category: process_creation
  product: windows
detection:
  selection_process:
    Image|endswith:
    - \powershell.exe
    - \cmd.exe
    - \rundll32.exe
    - \regsvr32.exe
    CommandLine|contains:
    - DownloadString
    - IEX(
    - '/s /n /u /i:'
    - sc create
    - start-process
  condition: selection_process
falsepositives:
- Legitimate enterprise administrative scripts during approved change windows
- Authorized IT software deployment utilities and backup management agents
level: high

rule MALWARE_WIN_ORCUS_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Orcus 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 = "orcus" 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. Immediately sever the endpoint from the network to terminate the active Orcus session, halting data exfiltration and preventing the attacker from triggering a BSOD.
2. Do NOT reboot the machine immediately; capture a forensic memory image to extract the active Orcus configuration and C2 details.
3. Force a global password reset for all accounts accessed by the user, as Orcus aggressively targets saved browser and email credentials.
4. Assume the machine is fully compromised; perform a clean operating system rebuild to ensure complete eradication.

What to Avoid

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

1. Do not leave the machine connected to the network during triage; the attacker has live access and can manually destroy evidence.
2. Avoid relying solely on file deletion; Orcus often runs in memory and will recreate deleted files if the injected process is not killed.

References & External Analysis

• Canadian Radio-television and Telecommunications Commission (CRTC) - Orcus Technologies Enforcement Decision
• Palo Alto Networks Unit 42 - Analysis of Orcus RAT Plugins and Cybercrime Adoption
• Search "orcus" on VirusTotal (External Analysis)
• Search "orcus" on Any.Run (Sandbox Sandbox)
• Search "orcus" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Backdoor)

Explore other documented threats in the same operational category:

• Koutodoor
• Opanki
• Hacdef
• Bagle
• Rpdpatch
• Shadowhammer
• Bersek
• Darkhotel

Machine-readable

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