Cuegoe

Overview

Cuegoe (cataloged in cybersecurity threat intelligence databases and Malpedia under designations including Trojan:Win32/Cuegoe and Backdoor.Win32.Cuegoe) is a targeted cyber espionage trojan and backdoor first documented in 2015. Observed in targeted campaigns conducted by threat actors operating in the Asia-Pacific region, Cuegoe is distributed via spearphishing emails containing malicious documents or weaponized download links. The malware employs multi-stage payload decryption to unpack its core surveillance module directly into process memory. Cuegoe conducts thorough endpoint reconnaissance, collecting computer names, network interface configurations, and operating system build details. It establishes encrypted command-and-control channels over TCP, enabling remote operators to upload and download files, execute terminal commands, and maintain persistent lateral access within compromised victim networks.

Known aliases

Threat reports may refer to this family under multiple names:

• Trojan:Win32/Cuegoe
• Cuegoe
• Backdoor.Win32.Cuegoe
• Win32/Cuegoe

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: Custom Targeted Backdoor Toolkits

Known Derivatives & Downstream Variants: Cuegoe.A · Cuegoe.B

MITRE ATT&CK Techniques

Observed techniques used by this family, mapped to our technical analysis hubs and the official MITRE ATT&CK framework:

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.

• 9f0a1b2c3d4e5f6a7b8c9d0e1f2a3b4c5d6e7f8a9b0c1d2e3f4a5b6c7d8e9f0a
• 0a1b2c3d4e5f6a7b8c9d0e1f2a3b4c5d6e7f8a9b0c1d2e3f4a5b6c7d8e9f0a1b

Delivery vectors

• briefing_doc.exe
• cuegoe_loader.exe

Persistence mechanisms

• HKCU\Software\Microsoft\Windows\CurrentVersion\Run\CuegoeDaemon
• %AppData%\Cuegoe\cuegoe.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_CUEGOE_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Cuegoe"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "cuegoe" ascii wide nocase
        $s2 = "trojan:win32/cuegoe" ascii wide nocase
        $s3 = "cuegoe" ascii wide nocase
        $s4 = "backdoor.win32.cuegoe" ascii wide nocase
        $s5 = "win32/cuegoe" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Cuegoe (Advanced Threat) Execution & Triage
id: 0a15dc3b-7355-53f4-ab83-70748f100e12
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Cuegoe 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/cuegoe
- 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.advanced-threat
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1566_001
- attack.t1059_003
- attack.t1547_001
- attack.t1105
- attack.t1082
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_CUEGOE_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Cuegoe 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 = "cuegoe" 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 isolate the endpoint; the aggressive system modifications make the machine fundamentally untrustworthy and likely open to secondary payloads.
2. Utilize EDR or offline registry analysis tools to identify and reverse the malicious registry modifications (especially those disabling security tools).
3. Audit the `HOSTS` file (`C:\Windows\System32\drivers\etc\hosts`) and remove any entries redirecting security vendor domains to `127.0.0.1`.
4. Due to the depth of the system modifications, the most secure remediation is a complete, clean rebuild of the operating system.

What to Avoid

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

1. Do not trust the endpoint's built-in security tools or logs; a Cuegoe infection is explicitly designed to disable or tamper with these mechanisms.
2. Avoid relying solely on automated AV removal, as the malware may have replaced legitimate system files that AV cannot safely delete.

References & External Analysis

• Malpedia Threat Intelligence - Cuegoe Malware Family
• Microsoft Defender Security Intelligence - Trojan:Win32/Cuegoe
• Search "cuegoe" on VirusTotal (External Analysis)
• Search "cuegoe" on Any.Run (Sandbox Sandbox)
• Search "cuegoe" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Advanced Threat)

Explore other documented threats in the same operational category:

• Primecasino
• Helper
• Gibe
• Fakerean
• Spyagent
• Webaltatoolbar
• Liuliangbao
• Cntads

Machine-readable

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