Idlebuddy

Overview

PUA:Win32/Idlebuddy is a persistent Potentially Unwanted Program (PUA) that functions primarily as a stealthy **Cryptominer** and distributed computing node. It is designed to hijack the infected endpoint's CPU and GPU resources to mine cryptocurrency (often Monero) for the developers, specifically engineering its execution to only occur when the user is away from the computer to evade detection.

Understanding the Idlebuddy Threat
To an end-user, Idlebuddy is designed to be invisible. They might occasionally notice the computer's fans spinning loudly when they walk into the room, but the noise stops as soon as they move the mouse. For an enterprise, Idlebuddy represents the theft of computing resources (Cryptojacking), resulting in increased electricity costs, hardware degradation, and severely reduced endpoint lifespan.

Execution and Evasion Mechanics
Idlebuddy is heavily distributed via software bundlers, often hidden inside installers for free games or utility software (`T1189`). Upon execution, it installs itself deeply into the system, establishing persistence via Registry Run keys or hidden Scheduled Tasks (`T1547.001`). Its defining characteristic is its evasion routine (`T1489`). It utilizes Windows APIs (like `GetLastInputInfo`) to monitor keyboard and mouse activity. The actual mining payload (often a modified version of XMRig) is only launched when the system has been completely idle for a specific duration (e.g., 10 minutes). The moment the user moves the mouse or opens the Task Manager, Idlebuddy instantly suspends or kills the mining process, dropping CPU usage back to normal before the user can see what was causing the lag.

Indicators of Compromise & Impact
The primary impact is resource theft and hardware wear. Host-based IoCs include EDR alerts for the creation of processes resembling known cryptominers (e.g., `ib.exe`, `idlebuddy.exe`), or sudden, massive spikes in CPU/GPU utilization that immediately drop when a user logs in. Network IoCs include continuous outbound traffic to known cryptocurrency mining pools (e.g., Stratum protocol traffic) over non-standard ports (like 3333 or 4444) when the machine is locked.

MITRE ATT&CK Techniques

Observed techniques used by this family, mapped to the MITRE ATT&CK framework:

Generated Detections (Boilerplate)

These YARA and Sigma rules are auto-generated based on the family name and aliases. They must be heavily tuned before deployment in a production environment.

YARA Rule

rule MALWARE_WIN_IDLEBUDDY {
    meta:
        description = "Detects Idlebuddy (advanced_threat)"
        author = "SystemHelpdesk Boilerplate Generator"
        date = "2026-07-06"
    strings:
        $s1 = "idlebuddy" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

Sigma Rule

title: Suspicious Idlebuddy Activity
id: 9135e0fed8c16b5c90074295616076f2
status: experimental
description: Detects generic indicators of the idlebuddy malware family.
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith:
            - '\cmd.exe'
            - '\powershell.exe'
        CommandLine|contains:
            - "*idlebuddy*"
    condition: selection
level: medium

Containment & Response Steps

Ordered checklist for responders. Adapt to your environment and engage professional support for active incidents.

1. Use the Windows Control Panel to attempt uninstallation of the software; however, Idlebuddy often uses deceptive uninstallers that leave the mining components behind.
2. Deploy an enterprise adware/PUA removal tool to locate and strip the hidden scheduled tasks and registry hooks.
3. Review firewall logs for any endpoints establishing long-lived TCP connections to known cryptocurrency mining pools, and block those IPs at the perimeter.
4. If the software was installed without administrative privileges, audit the user's `%AppData%` folder for the hidden executables.

What to Avoid

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

1. Do not rely solely on the Windows Task Manager to find the malware, as its primary evasion tactic is to hide from it.
2. Avoid ignoring cryptominers; while they don't steal data, the initial access vector that allowed the miner in could be used to deploy ransomware next time.

References & External Analysis

• Search "idlebuddy" on VirusTotal (External Analysis)

Frequently Asked Questions

Related Families (Category: advanced_threat)

Explore other malware families in the same category:

• Sillyfdc
• Instally
• Qqware
• Simplyinstaller
• Jacard

Machine-readable

Get this profile as JSON: https://jordan123234-malware-families-explorer.static.hf.space/api/idlebuddy.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.