Nlbrute

Category: ransomware · Aliases: HackTool.NLBrute, RDP.BruteForcer, Win32/NLBrute · Sample count (EMBER 2018): 1 · Enrichment: insufficient_information · Updated: 2026-07-01T16:13:06Z

Category: RansomwareActor: Unknown / CybercriminalIndustry: Global / OpportunisticMotivation: Opportunistic

Overview

Executive Summary

NLBrute is a notorious, commercially available hacking tool specifically designed to perform high-speed, automated brute-force attacks against the Remote Desktop Protocol (RDP - Port 3389). It is widely utilized by initial access brokers and ransomware syndicates to compromise internet-facing Windows servers, establishing a persistent foothold within corporate networks.

Technical Architecture and Operational Tactics

NLBrute is highly efficient, capable of attempting thousands of credential combinations per minute. Its operational flow involves:

Target Acquisition: Attackers first utilize internet-wide scanning tools (like Masscan or ZMap) to identify servers with Port 3389 open to the public internet.
Brute-Forcing: NLBrute is then deployed against the identified targets, utilizing massive, curated dictionaries containing common usernames (Administrator, Admin) and millions of compromised passwords.
Evasion: The tool often supports the use of proxy lists (SOCKS4/5) to distribute the attack traffic across hundreds of IP addresses, making it difficult for basic rate-limiting or IP blocklists to thwart the attack.

Once NLBrute successfully guesses a valid credential pair, the attacker gains full, interactive GUI access to the compromised server, bypassing all perimeter defenses.

Threat Impact

An NLBrute compromise is a catastrophic security failure. By gaining RDP access, the attacker operates with the privileges of the compromised user (often a domain administrator). This allows them to seamlessly disable security software, deploy ransomware (like Dharma or Phobos), and exfiltrate sensitive corporate data without triggering malware alerts.

Defense and Resilience Strategies

RDP Hardening: Never expose RDP (Port 3389) directly to the public internet. Require users to connect via a secure Virtual Private Network (VPN) or a Remote Desktop Gateway before accessing internal RDP servers.
Multi-Factor Authentication (MFA): Enforce strict MFA for all RDP connections. Even if NLBrute successfully guesses the password, the attack will fail without the secondary authentication token.
Account Lockout Policies: Implement stringent account lockout policies (e.g., locking an account after 5 failed login attempts) to mathematically defeat brute-force methodologies.

Known aliases

Threat reports may refer to this family under multiple names:

MITRE ATT&CK Techniques

This family has been observed using the following ATT&CK techniques: T1110.001 T1133 T1078.002

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_NLBRUTE {
    meta:
        description = "Detects Nlbrute (ransomware)"
        author = "SystemHelpdesk Boilerplate Generator"
        date = "2026-07-06"
    strings:
        $s1 = "nlbrute" ascii wide nocase
        $s2 = "hacktool.nlbrute" ascii wide nocase
        $s3 = "rdp.bruteforcer" ascii wide nocase
        $s4 = "win32/nlbrute" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

Sigma Rule

title: Suspicious Nlbrute Activity
id: 32fd81c3b5cbff92eb24df43d43283be
status: experimental
description: Detects generic indicators of the nlbrute malware family.
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith:
            - '\cmd.exe'
            - '\powershell.exe'
        CommandLine|contains:
            - "*nlbrute*"
            - "*hacktool.nlbrute*"
            - "*rdp.bruteforcer*"
            - "*win32/nlbrute*"
    condition: selection
level: medium

References & External Analysis

Search "nlbrute" on VirusTotal (External Analysis)

Frequently Asked Questions

How do I remove the Nlbrute Ransomware from Windows?

Manual removal of Nlbrute is highly discouraged as it may leave persistence mechanisms intact. We recommend disconnecting the device from the internet and utilizing a professional incident response service or enterprise-grade EDR software to conduct a full forensic sweep.

Is Nlbrute a virus or a Ransomware?

Nlbrute is classified as a Ransomware. Unlike traditional viruses that infect files, modern malware like Nlbrute typically operates as a standalone payload designed to compromise systems, steal data, or deploy secondary stage implants.

What are the main symptoms of a Nlbrute infection?

Symptoms of Nlbrute can include unexpected system slowness, unauthorized outbound network traffic to unknown IP addresses, disabled security software, and suspicious background processes running from AppData or Temp directories.

Related Families (Category: ransomware)

Explore other malware families in the same category:

Protect Your Network Against Ransomwares

Want to prevent Nlbrute and similar threats from compromising your organization? Read our comprehensive defensive guide: Ransomware Protection Guide.

Need help with an active incident? Published by the SystemHelpdesk team.

Machine-readable

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