Doubleagent

Overview

Executive Summary

Technical Architecture and Exploitation

• Registry Manipulation: The attacker modifies a specific, legitimate Windows Registry key (`HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\`). They create a subkey named `VerifierDlls` and point it to their malicious DLL payload.
• Universal Injection: Once the registry key is set, the Windows OS itself will automatically load the attacker's malicious DLL into the target process (e.g., `explorer.exe`, `chrome.exe`, or even the antivirus engine's process like `MsMpEng.exe`) every single time that process is launched.
• Absolute Stealth: Because the injection is performed natively by the OS loader *before* the application even begins executing its own code, traditional antivirus hooks and user-mode EDR agents are completely blind to the injection.

Threat Impact

Defense and Resilience Strategies

• Registry Monitoring (FIM): Traditional file scanning cannot stop DoubleAgent. Defenses must rely on strict File Integrity Monitoring (FIM) and EDR rules that monitor the `Image File Execution Options` (IFEO) registry keys for unauthorized modifications.
• Protected Processes: Utilize Windows Protected Process Light (PPL) technology. Processes running as PPL (which should include enterprise EDR agents) prevent unsigned or unauthorized DLLs from being loaded, even via the Application Verifier mechanism.
• Privilege Management: The initial execution of the DoubleAgent technique requires administrative privileges to modify the HKLM registry hive. Enforcing the Principle of Least Privilege (PoLP) and strict UAC controls prevents the initial registry modification required to set up the attack.

Known aliases

Threat reports may refer to this family under multiple names:

• HackTool.DoubleAgent
• Exploit.ApplicationVerifier
• Riskware.DoubleAgent

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):

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_DOUBLEAGENT_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Doubleagent"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "doubleagent" ascii wide nocase
        $s2 = "hacktool.doubleagent" ascii wide nocase
        $s3 = "exploit.applicationverifier" ascii wide nocase
        $s4 = "riskware.doubleagent" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Doubleagent (Advanced Threat) Execution & Triage
id: 47c06d01-94bd-583d-9be6-1bf3f6b7e2b4
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Doubleagent 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/doubleagent
- 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.t1546_012
- attack.t1055_001
- attack.t1562_001
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_DOUBLEAGENT_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Doubleagent 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 = "doubleagent" 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. Enforce forensic network isolation on all suspected endpoints while maintaining an out-of-band telemetry conduit to capture live Doubleagent adversary activity.
2. Perform full memory dumps across identified staging nodes to extract memory-only implants, kernel rootkit hooks, and decrypted Doubleagent C2 infrastructure IP/domain lists.
3. Review Active Directory domain controller authentication logs for anomalous Kerberos ticket requests (Pass-the-Ticket, Golden Ticket) and unauthorized DCSync operations associated with Doubleagent.
4. Block all confirmed C2 domains, dynamic DNS endpoints, and proxy IP addresses across perimeter firewalls, proxies, and DNS security gateways.
5. Conduct an enterprise-wide sweep across surrounding subnets for secondary webshells, WMI event subscriptions, or remote execution tooling left behind by Doubleagent operators.

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 Doubleagent 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 Doubleagent 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 "doubleagent" on VirusTotal (External Analysis)
• Search "doubleagent" on Any.Run (Sandbox Sandbox)
• Search "doubleagent" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Advanced Threat)

Explore other documented threats in the same operational category:

• Iwin
• Slingshot
• Installm
• Megasearch
• Offerinstall
• Patchupplus
• Directdownloader
• Updatestar

Machine-readable

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