What it does. Detects suspicious Windows service installations (MITRE ATT&CK T1543.003) by parsing System event log Event ID 7045, analyzing service binary paths, and flagging indicators of persistence mechanisms via Sysmon/EDR telemetry. Use when hunting for new-service persistence after a suspected compromise, when Event ID 7045 fires for an unfamiliar service, or during incident response to enumerate service-based persistence on Windows hosts. Part of mukul975/Anthropic-Cybersecurity-Skills (817 security skills) (mukul975/Anthropic-Cybersecurity-Skills).

Install

• npx skills add mukul975/Anthropic-Cybersecurity-Skills --skill hunting-for-unusual-service-installations, or copy the skill folder into ~/.claude/skills/hunting-for-unusual-service-installations/.
• Raw file: curl -sL https://raw.githubusercontent.com/mukul975/Anthropic-Cybersecurity-Skills/HEAD/skills/hunting-for-unusual-service-installations/SKILL.md

SKILL.md (verbatim)

name: hunting-for-unusual-service-installations
description: Detects suspicious Windows service installations (MITRE ATT&CK T1543.003) by parsing System event log Event ID 7045, analyzing service binary paths, and flagging indicators of persistence mechanisms via Sysmon/EDR telemetry. Use when hunting for new-service persistence after a suspected compromise, when Event ID 7045 fires for an unfamiliar service, or during incident response to enumerate service-based persistence on Windows hosts.
domain: cybersecurity
subdomain: threat-hunting
tags:
- threat-hunting
- T1543.003
- service-installation
- persistence
- Event-7045
- Sysmon
- Windows-services
version: '1.0'
author: mahipal
license: Apache-2.0
d3fend_techniques:
- Platform Hardening
- System Configuration Permissions
- Restore Object
- Restore Database
- Asset Inventory
nist_csf:
- DE.CM-01
- DE.AE-02
- DE.AE-07
- ID.RA-05
mitre_attack:
- T1046
- T1057
- T1082
- T1083
- T1547

Hunting for Unusual Service Installations

Overview

Attackers frequently install malicious Windows services for persistence and privilege escalation (MITRE ATT&CK T1543.003 — Create or Modify System Process: Windows Service). Event ID 7045 in the System event log records every new service installation. This skill parses .evtx log files to extract service installation events, flags suspicious binary paths (temp directories, PowerShell, cmd.exe, encoded commands), and correlates with known attack patterns.

When to Use

• When investigating security incidents that require hunting for unusual service installations
• 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
• Windows System event log (.evtx) files
• Access to live System event log (optional, for real-time monitoring)
• Sysmon logs for enhanced process tracking (optional)

Steps

1. Parse System.evtx for Event ID 7045 (new service installed)
2. Extract service name, binary path, service type, and account
3. Flag services with suspicious binary paths (temp dirs, encoded commands)
4. Detect PowerShell-based service creation patterns
5. Identify services running as LocalSystem with unusual paths
6. Cross-reference with known legitimate service baselines
7. Generate threat hunting report with MITRE ATT&CK T1543.003 mapping

Expected Output

• JSON report listing all new service installations with risk scores, suspicious indicators, and remediation recommendations
• Timeline of service installation events with binary path analysis

Other files in this skill

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

references/api-reference.md (verbatim)

API Reference — Hunting for Unusual Service Installations

Libraries Used

• python-evtx: Parse Windows .evtx event log files
• lxml: XML parsing of EVTX record XML
• re: Regex matching for suspicious binary path patterns
• collections.Counter: Statistics aggregation

CLI Interface

python agent.py System.evtx parse
python agent.py System.evtx hunt
python agent.py System.evtx stats
python agent.py System.evtx full

Core Functions

parse_evtx_events(evtx_path) — Extract Event ID 7045 records

Opens .evtx file with evtx.Evtx(), iterates records, parses XML with lxml. Extracts: ServiceName, ImagePath, ServiceType, StartType, AccountName, timestamp. Namespace: http://schemas.microsoft.com/win/2004/08/events/event

analyze_service_path(image_path) — Binary path risk analysis

Matches against 17 suspicious patterns (temp dirs, PowerShell, encoded commands, LOLBins, download patterns). Checks against 5 legitimate path prefixes. Scoring: +20 for non-standard path, +15 per suspicious indicator. Max 100.

hunt_suspicious_services(evtx_path) — Main hunting engine

Combines parsing and analysis. Extra +20 risk for LocalSystem account with non-standard binary path. Results sorted by risk score descending.

generate_statistics(results) — Summary statistics

Counts risk distribution, top indicators, service account usage.

full_hunt(evtx_path) — Comprehensive threat hunt report

Suspicious Path Patterns

Legitimate Service Path Prefixes

• C:\Windows\System32\
• C:\Windows\SysWOW64\
• C:\Program Files\
• C:\Program Files (x86)\
• C:\Windows\Microsoft.NET\

Event ID 7045 Fields

MITRE ATT&CK Mapping

• T1543.003 — Create or Modify System Process: Windows Service
• Tactics: Persistence, Privilege Escalation

Dependencies

• python-evtx >= 0.7.4
• lxml >= 4.9.0

Back to mukul975/Anthropic-Cybersecurity-Skills (817 security skills) or Agent skills.