What Is Penetration Testing? Types, Methodologies, Compliance & CI/CD (2025 Guide)

Introduction

(Protecting Your Systems from Hackers)

Imagine the internet as a vast network of connected devices, each a potential target for cyberattacks. These attacks can cause widespread damage, steal data, disrupt operations, or even hold systems hostage. To prepare for these threats, security teams conduct a simulated attack called penetration testing, or pen testing for short. This involves testing their systems for weaknesses that hackers could exploit. It's like a security drill, helping organisations identify and fix problems before they become real disasters.

What is Penetration Testing?

Penetration testing, also known as pen testing, is a security exercise where a cybersecurity expert tries to find and exploit weaknesses in a computer system or network. This is done to identify and fix security flaws before malicious actors can exploit them. Think of it like a practice drill for your security defences.

Penetration testing isn’t one-size-fits-all. Beyond access models (black/white/gray box), teams scope by asset: Web & mobile apps, APIs, cloud (IaaS/PaaS/SaaS), networks (internal/external), wireless, and people/process via social engineering. Each target class surfaces different risks (e.g., BOLA in APIs, misconfig in cloud, auth flaws in web) and often requires different tooling and reporting depth. Map scope to real business risk and data sensitivity first, then choose the asset types to test.

Example - 'A retail chain hires a pen tester to test the security of its point-of-sale (POS) systems. The pen tester discovers that the POS systems are vulnerable to a malware attack that could steal credit card information from customers. The retail chain implements security measures to protect its POS systems and customer data.'

Checkout GPT-5 vs O3 vs GPT-4.1, Which one is better for Penetration Testing

Compliance: Where Pen Testing Fits

Penetration testing supports regulatory obligations by validating that controls actually work. Some frameworks explicitly require periodic pen tests—e.g., PCI DSS v4.0 requires organizations processing card data to conduct penetration tests—while others (HIPAA, GDPR, ISO 27001) use pen testing as a way to evidence due diligence and control effectiveness. Add the relevant citation and cadence to your security program so audits don’t stall.

Tools You’ll See in a Typical Engagement

Common toolchains combine recon/scanning (Nmap), traffic analysis (Wireshark/tcpdump), web/API testing (Burp Suite, OWASP ZAP), and exploit frameworks (Metasploit). Many testers work from Kali Linux, which bundles these utilities for faster workflows. Tool choice depends on scope and rules of engagement; the report should link each critical finding to the tools and techniques used.

How Often Should You Pen Test?

Run a full-scope pen test at least annually (or semiannually for high-risk environments), plus after major releases, architecture changes, or new internet-facing assets. Between full tests, use targeted mini-engagements for new APIs, cloud accounts, or critical services, and maintain continuous vulnerability management. Tie cadence to risk: the more change velocity and data sensitivity, the more frequently you test.

Benefits of penetration testing:

1. Identify and fix security weaknesses.

2. Reduce the risk of cyberattacks.

3. Improve compliance with industry regulations
   
   

Types of penetration testing:

1. Black-box testing: The pen tester has no prior knowledge of the system they are testing.

2. White-box testing: The pen tester has access to all of the information about the system they are testing.

3. Gray-box testing: The pen tester has some information about the system they are testing, but not all.

Penetration Testing Process

1. Planning: The pen tester gathers information about the system, defines the scope of the test, and identifies assets that are off-limits.

2. Reconnaissance: The pen tester gathers more information about the system, such as IP addresses, open ports, and running services.

3. Vulnerability scanning: The pen tester uses automated tools to scan the system for vulnerabilities, identifying known weaknesses in software, hardware, and the network.

4. Exploitation: The pen tester attempts to exploit the vulnerabilities they have identified.

5. Post-exploitation: The pen tester gathers evidence of their exploits and assesses the impact of the vulnerabilities. They provide a report outlining their findings and recommendations for remediation.

Penetration Testing vs. Vulnerability Scanning

Recognized Methodologies & Standards

To keep tests consistent and auditable, align with a known standard: PTES (Penetration Testing Execution Standard) for end-to-end workflow, NIST SP 800-115 for planning & techniques, and OWASP guidelines for application & API layers. Use these as your test plan backbone and reference them in the report’s methodology section to improve credibility with auditors and engineering teams.

Penetration testing and vulnerability scanning

Penetration testing and vulnerability scanning are both important tools for improving cybersecurity, but they serve different purposes.

Vulnerability scanning is an automated process that identifies known vulnerabilities in a system. It is a good way to get a quick overview of the security posture of a system, but it does not provide a comprehensive assessment of the system's security.

Penetration testing is a manual process that involves trying to exploit vulnerabilities in a system. It is a more thorough way to assess the security of a system, but it is also more time-consuming and expensive.

The key differences between penetration testing and vulnerability scanning:

Both are essential but not interchangeable: scanners find potential weaknesses; pen tests show what an attacker can actually do.

Pen tests go deeper and reduce false positives by exploiting findings; organizations typically run both for full coverage.

Vulnerability scanning should be used regularly to get a quick overview of the security posture of a system. It is also a good way to identify vulnerabilities that can be easily exploited.

Penetration testing should be used periodically to get a more comprehensive assessment of the security of a system. It is also a good way to identify vulnerabilities that are not easily found by automated scanners.

Scope & Rules of Engagement

Use this pre-engagement checklist to avoid scope creep and legal gray areas:

• In scope: domains, IP ranges, APIs, cloud accounts, mobile apps, third-party services.

• Out of scope: production data exfiltration, DDoS, phishing (unless approved), lateral movement in certain networks.

• Access model: black/white/gray box; credentials provided? test accounts?

• Windows: dates/time, rate limits, change freezes.

• Data handling: PII in logs, redaction, evidence retention.

• Success criteria: impact demonstration (e.g., unauthorized data access), proof-of-exploit format, retest window.

Guide To Do Penetration Testing

1. Phase 1: Planning and Reconnaissance

   • Define scope: Determine the systems to be tested and the types of tests to be conducted (black-box, white-box, or gray-box).

   • Gather information: Use publicly available sources (e.g., social media, job postings) and internal sources (e.g., network diagrams, documentation) to gather information about the target system.

   • Identify attack vectors: Analyze the gathered information to identify potential attack vectors, such as open ports, vulnerable software, and social engineering opportunities.
     
     

2. Phase 2: Scanning and Vulnerability Assessment

   • Network scanning: Use network scanners to identify open ports, running services, and other network vulnerabilities.

   • Vulnerability scanning: Use vulnerability scanners to identify known vulnerabilities in the target system's software, hardware, and firmware.

   • Manual vulnerability assessment: Perform manual testing to validate the findings of the automated scans and identify any additional vulnerabilities that may not be detected by automated tools.
     
     

3. Phase 3: Exploitation

   • Select vulnerabilities to exploit: Prioritize the vulnerabilities based on their severity and exploitability.

   • Develop exploits: Develop or utilize existing exploits to exploit the selected vulnerabilities.

   • Document exploits: Document the exploits and the steps taken to execute them.
     
     

4. Phase 4: Post-exploitation

   • Gather evidence: Gather evidence of the exploits, such as screenshots and logs.

   • Assess impact: Assess the impact of the exploits on the target system.

   • Recommend remediation: Recommend remediation measures to address the exploited vulnerabilities.
     
     

5. Phase 5: Reporting and Remediation

   • Prepare a report: Prepare a comprehensive report documenting the findings of the penetration test, including the identified vulnerabilities, exploits, and remediation recommendations.

   • Present findings: Present the findings to the organization's stakeholders, such as the IT team and management.

   • Remediate vulnerabilities: Collaborate with the IT team to remediate the identified vulnerabilities.
     
     

     

CI/CD: Add a Lightweight DAST Gate (GitHub Actions example)

Add a DAST smoke test to every PR to catch obvious issues early, then schedule weekly deeper scans. Example (GitHub Actions + OWASP ZAP Baseline):

Pair this with periodic manual pen tests for real-world exploitation coverage.

What “Good” Looks Like

A strong report opens with an executive summary (business impact, risk trends), then delivers finding-by-finding detail: description, affected assets/endpoints, reproduction steps, exploit evidence, risk rating & CVSS, and precise remediation with code/config deltas. Include a methodology section referencing PTES/NIST/OWASP and a retest results appendix. This format lets leadership prioritize quickly while giving engineers actionable fixes.

Red Team, Pen Test, and Purple Team—When to Use Each

Pen tests validate technical weaknesses in scoped assets. Red teaming simulates real adversaries across people, process, and tech, often without prior notice. Purple teaming blends attacker and defender: testers and the SOC work side-by-side to improve detections and response during the exercise. For maturing programs, add periodic purple team sessions to turn findings into measurable detection coverage.

Top Penentration Testing Tools

• Nmap: Nmap is an open-source network scanner that is used to identify open ports, running services, and other network vulnerabilities.
  
  

  

• Wireshark: Wireshark is an open-source network protocol analyzer that allows you to capture and analyze network traffic.
  
  

  

Frequently Asked Questions

What is penetration testing and why does it matter?

Penetration testing is a controlled “ethical hacking” exercise where security experts simulate real-world attacks to validate how exploitable your systems really are. Unlike a checkbox audit, a pen test chains vulnerabilities, abuses weak configurations, and mirrors attacker TTPs to reveal business impact, not just technical flaws. The result is risk-based insight that reduces breach likelihood, protects sensitive data, and hardens your attack surface across web apps, APIs, cloud accounts, and networks—grounded in methodologies like PTES, NIST SP 800-115, and the OWASP Testing Guide.

How is a penetration test different from a vulnerability scan?

A vulnerability assessment or automated scanner flags potential issues, but a penetration test proves exploitability by attempting to break in, pivot laterally, and escalate privileges. Testers validate or dismiss scanner findings, chain minor weaknesses into critical paths, and demonstrate impact with evidence, screenshots, and reproducible steps. This reduces false positives, prioritizes fixes by real risk rather than raw CVSS, and delivers context a security team and leadership can act on quickly.

Which types of penetration testing should I choose?

Your choice depends on goals, risk tolerance, and visibility needs. Black-box testing imitates an external attacker with no inside knowledge; white-box offers source code and architecture for depth; gray-box balances realism and efficiency. Domain-specific options include web and API testing, mobile app testing, internal and external network testing, cloud and container security, wireless, and social engineering. Align the mix with critical assets, compliance requirements, and change cadence to get the most actionable coverage.

How do I scope a pen test and set strong rules of engagement?

Effective scope defines in-bounds assets like domains, subdomains, APIs, cloud accounts, and third-party integrations, plus any production constraints, test data, and maintenance windows. Rules of engagement clarify allowed techniques, rate limits, account provisioning, data handling, success criteria, and emergency contacts, and they document legal authorization and safe-harbor language. Clear scoping prevents surprises, protects availability, and ensures testers can explore the full attack surface—especially in modern cloud, microservices, and CI/CD environments.

How often should penetration testing be done—and when should we retest?

Most teams run a comprehensive pen test at least annually, then add targeted tests after major code releases, new internet-facing services, cloud re-architectures, M&A integrations, or regulatory changes. High-change environments benefit from Penetration-Testing-as-a-Service (PTaaS) or smaller, more frequent sprints. Always schedule a retest to verify remediation, close the loop in your DevSecOps pipeline, and update risk registers. This cadence keeps controls aligned with evolving threats, OWASP Top 10 risks, and business priorities.

What should a good pen test report include—and how do we use it?

A strong report blends executive-ready summaries with technical depth: threat scenarios, kill chains, mapped controls (OWASP, NIST, ISO), evidence, and step-by-step reproduction. Findings should be prioritized by business impact, likelihood, and exploitability, not just severity scores, and paired with clear remediation guidance and quick wins. Feed issues into your ticketing system with SLAs, assign owners, and track a remediation retest. The goal isn’t paper—it’s measurable risk reduction and resilient, secure software.