Introduction

I recently wrapped up a web penetration test where I completely compromised the target application, and I wanted to share what worked, the steps I took, and the methodology behind it. This guide is for new penetration testers or anyone looking for a practical approach from real-world engagements.

In this blog I will cover:

• Pre-Engagement and Scoping Essentials
• 2-Week Action Plan
• Web Security Testing Methodology
• Attack Chains AKA Connecting the Dots
• Writing Winning Penetration Testing Reports
• Mindset and Stakeholder Relations

For the full video of this topic, go here: https://rumble.com/v706tmw-my-web-hacking-methodology-how-to-crush-web-app-penetration-tests.html

Pre-Engagement and Scoping Essentials

Before starting your engagement, proper scoping is critical. You need to know exactly what’s in play and arm yourself with the right documentation to hit the ground running.

Request these from the client:

• Asset inventory: A clear list of in-scope targets.
• Tech stack details: Know the app’s framework, languages, and dependencies.
• Network/architecture diagrams: Understand the app’s infrastructure.
• API documentation: Postman collections or Swagger files are gold.
• Test credentials: Accounts for various user roles to explore functionality.
• App walkthrough: A demo from devs to grasp the app’s flow.

Also, clarify the client’s compliance goals. Are they aiming for HIPAA (healthcare), PCI DSS (fintech), SOC 2, or HITRUST? This shapes your testing and reporting, as compliance drives the engagement’s purpose. Get this upfront, it is critical for the reporting phase.

2-Week Action Plan

Time is of the essence in a penetration test, so structure your two weeks(10 business days) to extract the most value. My QA background taught me to approach apps systematically, and here’s how I break things down:

Days 1-3: Recon and Mapping

Start with a thorough app walkthrough to understand its business logic and functionality. Run a proxy tool like Burp Suite or Caido to capture API calls and identify interesting endpoints. Note potential attack vectors—form inputs, URL parameters, or file uploads. Modern apps rarely have low-hanging CVEs. Instead, vulnerabilities often hide in business logic or APIs. Look for quirks in how the app behaves and flag anything that looks exploitable.

Days 4-5: OWASP WSTG Checklist

The OWASP Web Security Testing Guide (WSTG) is your starting point, not your Bible. Spend these days systematically working through its checklist to cover authentication, authorization, input validation, and more. This keeps you from chasing rabbit holes like you would in a CTF. Document everything—potential injection points, misconfigurations, or weak session handling. By day 5, you should have a clear picture of the app’s attack surface.

Day 6-10: Attack Chains

Now would be the time to connect the dots. Most real-world wins come from chaining low or medium severity issues into critical exploits. I have a couple of examples that I’ll go over in the upcoming section on attack chains and connecting dots. But again, these aren’t random attacks you’d run from a Metasploit module, you need some creativity and technical skills to spot how vulnerabilities amplify each other and escalate it to a P0(High Priority) vulnerability.

Web Security Testing Methodology

Your methodology should blend structure with flexibility. Start with the OWASP WSTG checklist to ensure coverage, but don’t be a robot that just goes through checklists. This is a good way of getting replaced by automation. Modern apps are complex, and vulnerabilities often hide in unexpected behavior or even normal functionality, like poorly secured APIs or flawed business logic. Use tools like Burp Suite for intercepting traffic, but lean on manual testing to uncover logic flaws that scanners miss. Take detailed notes—screenshots, HTTP requests, and replication steps to build a solid case for each finding.

Attack Chains AKA Connecting the Dots

Rarely will you find a single “game ending” vulnerability unless the app is badly developed. Instead, you’ll combine smaller issues for higher impact. In one engagement, I found a low-severity IDOR that, when paired with a known and basic “feature”, let me access sensitive data. In another engagement, I chained a file upload bypass with a path traversal bug that opened the door for access into the internal network after I successfully triggered a reverse shell. 

From the threat actor’s perspective, you need to think, how can I escalate a minor flaw into a critical breach? This is where your creativity complements your technical skill and out of the box thinking.

Writing Winning Penetration Testing Reports

Your report is the deliverable that justifies your work, so make it count. Unlike a CTF writeup, you’re not just flexing your hacker skills and how you took complete control of the app. You need to log all findings – highs, mediums, and lows. Clients often pentest for compliance, so every vulnerability matters.

I use the CVSS v4.0 to score vulnerabilities, as it factors in impact and exploitability. For each finding, include:

• Clear description: Clearly state what the vulnerability is, and explain it in a way that a non technical stakeholder can understand it. It’s not just the developers that might look at the report, you may have some other C-level people or managers looking at the report to justify resources to fix the issue.
• Impact statement: Highlight risks like financial loss, data exposure, or reputational damage. Knowing how to communicate this can often expedite resolution of issues and vulns that you’ve found in the report.
• Proof of concept (PoC): Screenshots or steps to replicate the issue. Be very methodical and think about how a regular non security person can replicate this issue with minimal skill and tooling. 
• Remediation advice: Reference the OWASP Cheat Sheet Series for practical fixes devs can implement. Although, building an app yourself and learning to code significantly helps with this. I recommend learning web development frameworks like React, Flask and some PHP(for WordPress sites). Knowing these will give you a good understanding of how modern web apps are built and basically where things are at and how they work.

Be concise but thorough. A good report doesn’t just point out flaws, it shows the client how to fix them and why it’s worth their time and effort.

Mindset and Stakeholder Relations

Your mentality can make or break an engagement. You’re not there to shame the developer’s work, you’re on the same team. Adopt a collaborative vibe: reassure devs that your findings help them build a better app, not threaten their jobs. Present solutions, not demands. During kickoffs or debriefs, listen to their concerns and explain how your work aligns with their goals, like meeting compliance or protecting customers. A positive relationship turns a one-off gig into a long-term partnership.

Conclusion

A successful web penetration test isn’t just about finding vulnerabilities—it’s about delivering value. Prep thoroughly, follow a structured methodology, hunt for attack chains, and write a report that helps the client’s organization meet compliance while also giving them peace of mind. Above all, stay curious, creative, and collaborative. That’s how you turn a good pentest into a great one.

– Z333RO