Penetration testing has rapidly evolved from being a niche practice to a critical mainstream cybersecurity capability over the past decade. Organizations across sectors are now mandating simulated hacking assessments against their networks, systems, and applications to identify security gaps before attackers exploit them.
But while penetration testing goals remain centered on uncovering vulnerabilities before they turn into full-blown data breaches, the tools, techniques, and reporting methodologies have significantly matured in line with the threat landscape.
In this comprehensive guide, we will map out the end-to-end penetration testing lifecycle covering scoping, planning, execution, findings analysis, and reporting. Read on to brush up your understanding of today‘s pen testing best practices.
A Brief History of Pen Testing Methodologies
Before digging into how modern pen tests are performed, it helps to take a quick look at how we arrived here.
Late 1990s – Early pen tests focused heavily on network infrastructure instead of applications using port scanning tools like nmap, packet sniffers, and network mappers to find misconfigured systems. Vulnerability data was manually aggregated into basic reports shared across email and spreadsheets.
Early 2000s – As custom web applications became widespread, the focus expanded to uncovering input validation flaws like SQL injection, cross-site scripting which enabled stealing data. Commercial scanning tools offered automated vulnerability testing capabilities for the first time.
2010s – Cloud adoption led to new pen testing complexities for factors like broad network exposures, frequent build changes, shared security models. Concept of DevSecOps took hold to integrate security earlier during development phases across teams.
Present Day – The pen testing market [is estimated to grow] to $5.6 billion by 2025 driven by modern attack techniques involving chaining of multiple vulnerabilities, business logic issues, authentication flaws etc. Regulation also plays a role in pushing comprehensive testing to demonstrate due security care and diligence before actual incidents.
Pen Testing vs Other Security Testing Frameworks
While terminology is often incorrectly used interchangeably, it helps to distinguish penetration tests from related practices:
Vulnerability Assessments focus on a narrow surface area to scan and enumerate as many security flaws as possible exhaustively but don‘t verify real-world exploitability.
Security Audits take a broader view for reviewing policies, processes, controls across management and technology domains against a compliance checklist but don‘t probe for unknown risks.
Risk Assessments offer directional guidance on improving defenses based on asset criticality, data sensitivity and threat models – morelst focused on business context vs. pure security.
Whereas penetration tests adopt an adversarial mindset to demonstrate real-world compromise potential, viability of exploitation for found vulnerabilities while balancing business risk. Tests also factor in human elements (phishing, social engineering) in addition to just technology and policy controls.
Now that we have established penetration testing purpose and uniqueness, let‘s get into the methodological nitty-gritties involved.
Phase 1 – Planning and Reconnaissance
Every good penetration test starts with defining scope and objectives then progresses towards information gathering.
Scoping the Engagement
Proper scoping alignment ensures the client organization and the pen testing team share common expectations on what security assessments will cover.
For example, unclear statements like “Validate security for client XYZ” compare poorly to elaborated scopes such as “Assess vulnerabilities in externally-facing servers, web applications, network appliances at site A with IP subnet X accessible anonymously without authentication”.
Detailed scoping statements prevent surprise findings mid-test that business teams may flag as out-of-scope. It also provides legal cover for pen testers regarding authorized actions and contact points if things go wrong.
Rules of Engagement (ROE) expand on the scope by clearly calling out:
- Non-intrusive vs intrusive testing guidelines
- Authorization for social engineering attempts
- Communication protocols in case of test-caused system disruptions
- Requirements like minimizing user visibility or business impacts
- Mandated hours for performing tests (business hours vs after hours)
- Guidelines for backing up systems and restoring post-test environments
Non-Disclosure Agreements (NDAs) also play an instrumental role in assuring clients that discovered vulnerabilities and sensitive data stay confidential.
See Appendix A for a sample penetration testing engagement letter template covering scope, ROE, NDAs etc.
Open Source Intelligence Gathering
Armed with a well-defined scope and engagement ground rules, pen testing teams start gathering intelligence about the target environments.
Passive Analysis data points help map out external visibility and digital footprint. Examples include:
- Domain names, IP addresses, network infrastructure intel extracted from WHOIS records, DNS lookups
- Organization structure, technologies used, exposed employee names/roles from LinkedIn profiles
- Code repositories, credentials exposed at paste sites like Pastebin sourced via Google dorks
- Metadata from documents, images revealing back-end infrastructure details
Active Reconnaissance then allows interrogating assets more directly:
- Banner grabbing through port scans to fingerprint OS versions, services
- Testing mail servers for user account enumerations to prime password cracking attempts
- Mining publicly accessible web apps for clues exposing internal topology
A sample pre-assessment harvest template tailored to client domain and geography is attached as Appendix B highlighting areas of interest.
Such extensive reconnaissance enables understanding weak points for focused follow-on probing.
Phase 2 – Scanning and Vulnerability Analysis
Equipped with target intel from earlier recon, pen testers start scanning to discover security misconfigurations and coding flaws.
Network Scans present an easy starting point before progressing to granular checks:
- Detecting firmware versions, unpatched services through banner grabbing
- Finding open SMB shares allowing anonymous access
- Identifying databases visible externally with default admin passwords
Web Application Scans uncover application-centric issues:
- Injecting
OR 1=1--payloads into search forms to test for SQLi - Attempting common traversal sequences like ../../../etc/passwd
- Checking password reset forms for authentication bypass weaknesses
- Probing interfaces for DOM XSS, CSRF, logic flaws
Under the hood, these scans rely on vulnerability scanning tools:
| Category | Tools | Approach |
|---|---|---|
| Commercial | Rapid7 InsightAppSec, Tenable Nessus, PortSwigger Burp | Broader language coverage, user-friendly UI, normalized severity scoring |
| Open Source | sqlmap, Nikto, nmap, DirBuster | Lightweight, frequent updates, highly configurable |
See Appendix C for sample scoring criteria to standardize vulnerability classifications across tools for improved analysis.
The scan findings generate the blueprint to hypothesize exploitation scenarios next.
Phase 3 – Gaining Access and Privilege Escalation
Until now, the identified vulnerabilities have been theoretical. This phase focuses on proving actual compromise potential.
The goals span:
- Initial Access – Get an initial foothold on low-hanging flaws
- Privilege Escalation – Expand access horizontally and vertically
- Impact Analysis – Evaluate data breach impact
Initial Access
Depending on earlier recon and scanning, testers map out different theoretical entry points:
- Web apps – Flaws like SQLi, XXE, SSRF, IDOR, authentication bypasses
- Exposed Services – Remote code executions on vulnerable SMB, RDP, databases
- Phishing – Droppers, keyloggers granting user-level access via emails
The most convenient vulnerabilities provide initial access, typically web-centric these days according to industry breach reports.
Privilege Escalation
With low-privilege first access, attackers explore lateral pathways towards critical data access:
Vertical Escalation
- Kernel, driver exploits leading to administrator rights
- Password reuses from memory dumps or shared accounts
- Service account hijacking via misconfigurations
- User privilege abuse via malformed tokens or transient permissions
Horizontal Escalation
- Network sniffers, port scanners finding additional weak points
- Cloud metadata side channels granting server access
- Backdoors allowing continued post-exploit access
See Appendix D on common privilege escalation techniques (PDF warning)
Impact Analysis
Best way to evaluate potential breach impact is attempting data extractions:
- Downloading database dumps containing PII, credentials
- Compressing terabytes of proprietary source code
- Transferring financial reports, customer information etc. via secure shell
This demonstrates the importance of adopting a stepped approach – bypassing countermeasures by chaining discrete flaws until eventually reaching crown jewels.
Phase 4 – Reporting and Remediation Recommendations
Post successfully breaking in through tests, the next key responsibility is outlining remediation measures to fill gaps.
Reporting Best Practices
Reports act as the enduring reference encapsulating all pen test results, recommendations that security teams revisit regularly beyond the initial presentation.
Key Elements Include:
Executive Summary
Overview of major findings, risk ratings, remediation roadmaps and costs tailored for leadership.
Technical Findings
Granular vulnerability details, proof of concepts, access trajectories for action by security engineers.
Appendix
Raw scan outputs that serve as evidentiary supplement should questions arise later.
See Appendix E containing excerpts from a sample pen test report template.
Presentation Deck
Summarizes findings additionally in an abbreviated visual format for verbal briefings.
Remediation and Hardening
Armed with assessment insights, organizations embark on hacking back security debt:
Validating Results
Attempting similar exploitation helps verify findings are in fact reproducibly vulnerable versus false positives.
Assigning Issue Owners
Mapping findings to teams responsible for affected assets – app owners, server admins etc. is key to driving accountability.
Prioritizing via Risk Ratings
Ranking allows logically viewing critical remote code executions separately from low risk XSS flaws for example.
Updating Countermeasures
Installing security updates, expanding logging and incident response playbooks based on uncovered scenarios.
Scheduling Future Tests
Validating that new defenses indeed prevent past findings while catching additional threats.
Enabling Impactful Pen Testing
Here are some tips for maximizing effectiveness of your penetration testing engagements:
Integrate Security Earlier – Shift left by testing code, configurations pre-production during development cycles for significant cost savings.
Test More Frequently – Scheduling recurring small-scope tests quarterly offers more value vs. just annual full tests.
Focus on Risk Not Just Compliance – Go beyond checking boxes to emphasize findings relevance.
Verify Remediations – Redo tests post-fixes to validate issues are comprehensively addressed, not just peripherally patched.
Level Up Skill Sets – Invest in building in-house offensive security skills to reduce outsourcing dependency.
The end goal is institutionalizing testing as a habitual culture and capability rather than a sporadic phase.
Conclusion
This guide covered a lot of ground around planning and performing penetration testing fueled by dramatic real-world attack shifts in recent years. While exterior threat factors will undoubtedly continue advancing, having an introspective controlled pen testing practice helps organizations counter the external risk proactively.
What aspects of pen testing methodologies interest you most from an adoption standpoint? Are there any sections you would like covered in more technical depth? Looking forward to perspectives and feedback to help strengthen future guidelines.
