Activitymonitor

Overview

Activitymonitor (classified in antivirus detection telemetry under designations including Trojan:Win32/Activitymonitor, Trojan.Win32.Activitymonitor, and Win32/Activitymonitor) is a multi-stage trojan engineered to disguise itself as legitimate software, execute unauthorized commands, and coordinate with external command-and-control infrastructure. Disseminated across enterprise networks and consumer workstations via social engineering, phishing attachments, malicious drive-by downloads, or weaponized software cracks, Activitymonitor 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 deceptive executable masquerading, registry run key autostart, system telemetry gathering, and remote C2 beaconing. 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:

• Trojan:Win32/Activitymonitor
• Trojan.Win32.Activitymonitor
• Win32/Activitymonitor

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.
• T1113: Monitor for frequent or unauthorized screen captures or clipboard reads. Restrict background applications from accessing desktop APIs.

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_ACTIVITYMONITOR_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Activitymonitor"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "activitymonitor" ascii wide nocase
        $s2 = "trojan:win32/activitymonitor" ascii wide nocase
        $s3 = "trojan.win32.activitymonitor" ascii wide nocase
        $s4 = "win32/activitymonitor" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Activitymonitor (Trojan) Execution & Triage
id: 6e2c39f9-d445-5c47-b56a-5c2690e887e4
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Activitymonitor 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/activitymonitor
- 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.t1059_003
- attack.t1027
- attack.t1547_001
- attack.t1071_001
- attack.t1105
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_ACTIVITYMONITOR_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Activitymonitor 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 = "activitymonitor" 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 infected endpoint from the network to halt the exfiltration of the recorded logs.
2. Assume all credentials, emails, and sensitive documents accessed on the compromised machine have been compromised. Initiate an enterprise-wide password reset for the affected user.
3. Preserve the system state (RAM dump) to analyze the running spyware process and locate the local staging directory where it stores its encrypted logs before exfiltration.
4. Review firewall and proxy logs to identify the external servers used for exfiltration and block them.

What to Avoid

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

1. Do not allow the user to change their passwords *from the infected machine*; the spyware will simply record the new credentials.
2. Avoid closing the incident simply by uninstalling the software; ensure a full investigation determines exactly what data was lost and who installed the tool.

References & External Analysis

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

Frequently Asked Questions

Related Threats (Category: Trojan)

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• Generictka
• Tear
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Machine-readable

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