What it does. Detect RDP brute force attacks by parsing Windows Security Event Logs Part of mukul975/Anthropic-Cybersecurity-Skills (817 security skills) (mukul975/Anthropic-Cybersecurity-Skills).

Install

• npx skills add mukul975/Anthropic-Cybersecurity-Skills --skill detecting-rdp-brute-force-attacks, or copy the skill folder into ~/.claude/skills/detecting-rdp-brute-force-attacks/.
• Raw file: curl -sL https://raw.githubusercontent.com/mukul975/Anthropic-Cybersecurity-Skills/HEAD/skills/detecting-rdp-brute-force-attacks/SKILL.md

SKILL.md (verbatim)

name: detecting-rdp-brute-force-attacks
description: Detect RDP brute force attacks by parsing Windows Security Event Logs
  (EVTX files, via python-evtx) for failed logon patterns (Event ID 4625, Logon
  Type 10/3), correlating with successful logons (Event ID 4624), and analyzing
  NLA failures and source IP frequency. Use when investigating exposed RDP endpoints,
  building SIEM detection rules for credential guessing, or confirming whether
  a compromised account followed a brute-force pattern.
domain: cybersecurity
subdomain: threat-detection
tags:
- threat-detection
- rdp
- brute-force
- windows-event-logs
- blue-team
- siem
version: '1.0'
author: mahipal
license: Apache-2.0
nist_csf:
- DE.CM-01
- DE.AE-02
- DE.AE-06
- ID.RA-05
mitre_attack:
- T1021.001
- T1110.001
- T1110.003
- T1078

Detecting RDP Brute Force Attacks

Overview

RDP brute force attacks target Windows Remote Desktop Protocol services by attempting rapid credential guessing against exposed RDP endpoints. Detection relies on analyzing Windows Security Event Logs for Event ID 4625 (failed logon with Logon Type 10 or 3) and correlating with Event ID 4624 (successful logon) to identify compromised accounts. This skill covers parsing EVTX files with python-evtx, identifying attack patterns through source IP frequency analysis, detecting NLA bypass attempts, and generating actionable detection reports.

When to Use

• When investigating security incidents that require detecting rdp brute force attacks
• When building detection rules or threat hunting queries for this domain
• When SOC analysts need structured procedures for this analysis type
• When validating security monitoring coverage for related attack techniques

Prerequisites

• Python 3.9+ with python-evtx, lxml libraries
• Windows Security EVTX log files (exported from Event Viewer or collected via WEF)
• Understanding of Windows authentication Event IDs (4624, 4625, 4776)
• Familiarity with RDP Logon Types (Type 3 for NLA, Type 10 for RemoteInteractive)

Steps

Step 1: Export Security Event Logs

Export Windows Security logs to EVTX format using Event Viewer or wevtutil:

wevtutil epl Security C:\logs\security.evtx

Step 2: Parse Failed Logon Events

Use python-evtx to parse Event ID 4625 entries, extracting source IP, target username, failure reason (Sub Status), and Logon Type fields.

Step 3: Analyze Attack Patterns

Identify brute force patterns by:

• Counting failed logons per source IP within time windows
• Detecting username spray attacks (many usernames from one IP)
• Correlating 4625 failures with subsequent 4624 success from same IP

Step 4: Generate Detection Report

Produce a JSON report with top attacking IPs, targeted accounts, time-based analysis, and compromise indicators.

Expected Output

JSON report containing:

• Total failed logon events and unique source IPs
• Top attacking IPs ranked by failure count
• Targeted usernames and failure sub-status codes
• Successful logons following brute force attempts (potential compromises)
• Time-series analysis of attack intensity

Other files in this skill

• LICENSE
• references/api-reference.md
• scripts/agent.py

references/api-reference.md (verbatim)

API Reference: Detecting RDP Brute Force Attacks

Windows Security Event IDs

Logon Types for RDP

Failure Sub-Status Codes

python-evtx Library Usage

import Evtx.Evtx as evtx

with evtx.Evtx("Security.evtx") as log:
    for record in log.records():
        xml_str = record.xml()

Install: pip install python-evtx lxml

wevtutil Export Commands

# Export Security log to EVTX
wevtutil epl Security C:\logs\security.evtx

# Query failed RDP logons
wevtutil qe Security /q:"*[System[(EventID=4625)] and EventData[Data[@Name='LogonType']='10']]" /f:text

# Count recent failed logons
wevtutil qe Security /q:"*[System[(EventID=4625)]]" /c:100 /rd:true /f:text

Detection Thresholds

References

• Microsoft Event 4625: https://learn.microsoft.com/en-us/windows/security/threat-protection/auditing/event-4625
• Microsoft Event 4624: https://learn.microsoft.com/en-us/windows/security/threat-protection/auditing/event-4624
• python-evtx: https://github.com/williballenthin/python-evtx
• LogonTracer: https://github.com/JPCERTCC/LogonTracer

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