Atomicrat

Overview

Atomicrat (classified in antivirus detection telemetry under designations including Backdoor:Win32/Atomicrat, Backdoor.Win32.Atomicrat, and Win32/Atomicrat) is a interactive remote access trojan and backdoor providing remote threat actors with unauthorized terminal control, file manipulation, and surveillance. Disseminated across enterprise networks and consumer workstations via social engineering, phishing attachments, malicious drive-by downloads, or weaponized software cracks, Atomicrat executes an initial reconnaissance phase upon system ingress. The binary evaluates host privileges, detects active hypervisors and sandbox environments to evade behavioral analysis, and establishes resilient autostart persistence by configuring registry keys under HKCU\Software\Microsoft\Windows\CurrentVersion\Run or registering background Windows services. Operational mechanics characteristic of this family include reverse shell connections, process hollowing, privilege escalation, and lateral movement reconnaissance. Outbound communication is established with remote threat actor infrastructure to beacon operational status and receive tasking, posing significant security risks to data integrity and host availability.

Known aliases

Threat reports may refer to this family under multiple names:

• OSX.AtomicRAT
• Trojan.Atomic
• Backdoor.AtomicRAT
• Backdoor:Win32/Atomicrat
• Backdoor.Win32.Atomicrat
• Win32/Atomicrat

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.
• T1059: Restrict execution of scripting languages such as PowerShell, VBScript, or Python to authorized administrators. Enforce Script Block Logging.
• T1113: Monitor for frequent or unauthorized screen captures or clipboard reads. Restrict background applications from accessing desktop APIs.
• 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):

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_ATOMICRAT_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Atomicrat"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "atomicrat" ascii wide nocase
        $s2 = "osx.atomicrat" ascii wide nocase
        $s3 = "trojan.atomic" ascii wide nocase
        $s4 = "backdoor.atomicrat" ascii wide nocase
        $s5 = "backdoor:win32/atomicrat" ascii wide nocase
        $s6 = "backdoor.win32.atomicrat" ascii wide nocase
        $s7 = "win32/atomicrat" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Atomicrat (Backdoor) Execution & Triage
id: bad21cc5-69f5-5e2f-bbd4-f3c066d9dd01
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Atomicrat 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/atomicrat
- 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.t1059_003
- attack.t1055
- attack.t1573
- attack.t1547_001
- attack.t1070
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_ATOMICRAT_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Atomicrat 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 = "atomicrat" 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 Atomicrat from retrieving secondary stage payloads.
2. Capture process memory triage to detect and terminate malicious threads injected by Atomicrat 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 Atomicrat 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 Atomicrat 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 Atomicrat 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 Atomicrat 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

• Microsoft Defender Threat Encyclopedia - Backdoor:Win32/Atomicrat
• Kaspersky Threat Intelligence - Backdoor.Win32.Atomicrat
• MITRE ATT&CK - Enterprise Techniques
• Search "atomicrat" on VirusTotal (External Analysis)
• Search "atomicrat" on Any.Run (Sandbox Sandbox)
• Search "atomicrat" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Backdoor)

Explore other documented threats in the same operational category:

• Scarsi
• Salgorea
• Winnti
• Hafen
• Teamviewer
• Shadowhammer
• Younglotus
• Revenge

Machine-readable

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