Ngrbot

Overview

NGRBot (extensively documented as Dorkbot, Worm:Win32/Dorkbot, Worm.Win32.Ngrbot, and W32.IRCBot.NG) is an infamous, multi-functional Windows botnet and self-propagating worm active since 2011. Operating at massive scale across more than 190 countries and infecting well over one million endpoints at its zenith, Dorkbot/NGRBot was the subject of official US-CERT/CISA Technical Alert TA15-337A and a coordinated international law enforcement takedown involving Microsoft, Interpol, and the FBI. Built around an IRC-based command-and-control core, NGRBot propagates rapidly via removable USB storage devices (using infected LNK shortcuts and autorun hooks), peer-to-peer messaging networks (Skype, Windows Live Messenger), and social media phishing links. Once active on a host, NGRBot performs API-hooking and browser form-grabbing to intercept login credentials, online banking sessions, and email passwords. It also includes denial-of-service (DDoS) flood modules and systematically disables antivirus updates and security software domains by altering the local DNS resolution and Windows HOSTS configuration.

Known aliases

Threat reports may refer to this family under multiple names:

• Worm:Win32/Dorkbot
• Worm.Win32.Ngrbot
• NGRBot
• Dorkbot
• W32.IRCBot.NG
• Win32/Dorkbot

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: Classic Irc Worms

Known Derivatives & Downstream Variants: Dorkbot.A · Dorkbot.B · Ngrbot 2.0

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:

• T1056.004: Monitor for unauthorized keylogging, screen capturing, or web browser API hooking. Deploy EDR to detect API hooking.
• T1105: Implement network intrusion detection systems (NIDS) and host-based firewalls to block unauthorized inbound or outbound file transfers.

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.

• 8e9f0a1b2c3d4e5f6a7b8c9d0e1f2a3b4c5d6e7f8a9b0c1d2e3f4a5b6c7d8e9f
• 9f0a1b2c3d4e5f6a7b8c9d0e1f2a3b4c5d6e7f8a9b0c1d2e3f4a5b6c7d8e9f0a

Delivery vectors

• Infected USB removable media with weaponized LNK shortcuts
• Malicious download links sent via Skype and instant messaging

Persistence mechanisms

• HKCU\Software\Microsoft\Windows\CurrentVersion\Run\Ngrbot
• Injected process threads inside explorer.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_NGRBOT_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Ngrbot"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "ngrbot" ascii wide nocase
        $s2 = "worm:win32/dorkbot" ascii wide nocase
        $s3 = "worm.win32.ngrbot" ascii wide nocase
        $s4 = "ngrbot" ascii wide nocase
        $s5 = "dorkbot" ascii wide nocase
        $s6 = "w32.ircbot.ng" ascii wide nocase
        $s7 = "win32/dorkbot" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Ngrbot (Worm) Execution & Triage
id: e42d3df7-67bf-5b07-a47d-a4070faf8107
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Ngrbot 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/ngrbot
- https://malware-families-catalog.systemhelpdesk.com/defensive/ransomware-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.worm
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1091
- attack.t1055
- attack.t1056_004
- attack.t1498
- attack.t1562_001
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_NGRBOT_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Ngrbot 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 = "ngrbot" 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. Isolate the endpoint from network and internet access to sever IRC command-and-control communications.
2. Initiate organization-wide password resets for any corporate or financial accounts accessed from the infected host.
3. Examine and clean all removable USB storage devices connected to the endpoint to halt physical worm propagation.
4. Revert malicious modifications to the Windows HOSTS file and registry DNS configurations blocking security vendors.

What to Avoid

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

1. Do not connect clean USB drives to an infected system, as Dorkbot instantly writes malicious autorun files and hidden LNKs.
2. Avoid assuming credential compromise was limited to banking, as the botnet logs all browser and messaging credentials.

References & External Analysis

• CISA / US-CERT Alert TA15-337A - Dorkbot Botnet
• Microsoft Security Blog - Defeating the Dorkbot Botnet
• Huntress Threat Intel - Dorkbot / NGRBot Overview
• CISA Advisory: TA15-337A
• Search "ngrbot" on VirusTotal (External Analysis)
• Search "ngrbot" on Any.Run (Sandbox Sandbox)
• Search "ngrbot" on MalwareBazaar (Malware Samples)

North American Authority Advisory (CISA / NIST)

The Cybersecurity and Infrastructure Security Agency (CISA) has published an official US federal advisory on this family, which can be mapped to NIST Cybersecurity Framework (CSF) incident response controls: TA15-337A ↗

Frequently Asked Questions

Related Threats (Category: Worm)

Explore other documented threats in the same operational category:

• Chindo
• Conficker
• Cambot
• Lamer
• Mydoom
• Chir
• Ludbaruma
• Benjamin

Machine-readable

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