Web Application Penetration Testing: OWASP Top 10, Burp Suite and Manual Testing Methodology

Quick answer: Web application penetration testing means proving exploitable vulnerabilities by testing an application's authentication, authorization, input handling and business logic layers like a real attacker. The framework is the OWASP Top 10 2021: A01 Broken Access Control, A02 Cryptographic Failures, A03 Injection (including SQL injection and XSS), A04 Insecure Design, A05 Security Misconfiguration, A06 Vulnerable and Outdated Components, A07 Identification and Authentication Failures, A08 Software and Data Integrity Failures, A09 Security Logging and Monitoring Failures, A10 Server-Side Request Forgery (SSRF). The methodology is the OWASP Web Security Testing Guide (WSTG), the primary tool is Burp Suite. An automated scanner sweeps the surface; only manual testing finds business-logic and authorization flaws. So the two are needed together.

Web applications are the broadest and most frequently attacked internet-facing surface of organizations. In Verizon's annual breach reports, basic web application attacks rank among the top breach patterns, and most of these attacks use stolen credentials. Web application penetration testing does not treat this surface as a mere scanner report; it builds and proves, in an authorized way, the chains a real attacker would use.

This article complements our pieces on API security penetration testing and web site security service; here the focus is manual testing that deeply probes the application's own logic.

What the OWASP Top 10 is, and why it is the framework

The OWASP Top 10 is the OWASP Foundation's consensus list of the ten most critical security risks in web applications. The current stable version is 2021; in 2021 three new categories (A04 Insecure Design, A08, A10 SSRF) were added and others reorganized. OWASP announced a newer edition in 2025, but for a stable citation we anchor our tests on the 2021 list and refer to 2025 as the newer edition. The Top 10 is a risk map, not a test checklist; the actual methodology is the OWASP Web Security Testing Guide (WSTG), the open-source guide the world effectively uses to test the security of applications and services.

The most exploited vulnerabilities

A01 Broken Access Control and IDOR

In the OWASP Top 10 2021 the number-one risk is broken access control: a user reaching data or functions they are not authorized for. Its most common form is IDOR (Insecure Direct Object Reference): accessing someone else's data by changing the object identifier in a request (for example an account number). These are the flaws automated scanners most often miss, because you must know the application's business context and who should access what; only manual testing finds them.

A03 Injection: SQL Injection and XSS

In 2021 the Injection category also absorbed XSS, previously its own category. SQL injection is when user input is concatenated directly into a database query, letting the attacker manipulate the query to read or modify data. Cross-Site Scripting (XSS) is when the attacker injects executable script into a web page that runs in other users' browsers. Both are documented interactively at the PortSwigger Web Security Academy and are prevented with parameterized queries and output encoding.

A10 Server-Side Request Forgery (SSRF)

SSRF is when the attacker tricks the application into making a request on the server's behalf; it is especially dangerous in cloud environments for reaching internal services and metadata endpoints to leak credentials. Added to the Top 10 in 2021, this category became critical as cloud architectures spread.

A07 Identification and Authentication Failures

Weak password policies, flawed session management, breakable password-reset flows and missing multi-factor authentication fall here. In the pentest the authentication flow, session tokens and account-takeover scenarios are tested in detail.

Methodology: WSTG and ASVS

The OWASP Web Security Testing Guide (WSTG) is the de facto methodology penetration testers use worldwide, structured into topics such as information gathering, authentication testing, session management testing, authorization testing, input validation testing and business logic testing. OWASP ASVS (Application Security Verification Standard) provides a basis for testing technical security controls and defining secure-development requirements; it is also used as a requirements list in procurement contracts. At DSET we run tests under WSTG topics and map findings to ASVS levels.

Why automated and manual testing are both needed

Automated scanners (DAST tools) sweep a broad surface quickly, catch known patterns and are ideal for regression. But they miss business-logic flaws, authorization-bypass chains, multi-step account takeover and context-dependent IDOR, because they do not know what the application is supposed to do. Manual testing fills this gap: the expert understands the application's workflow and builds chains with human creativity. When source code is available, testing combined with static analysis goes deeper; see our source code security review (SAST, DAST, SCA).

The primary tool: Burp Suite

Burp Suite is PortSwigger's web vulnerability scanner and intercepting proxy; it is the industry-standard toolkit for web application penetration testing. It captures, modifies, repeats and automates requests; it is the backbone of manual testing. Our autonomous engine KAOS adds speed on the discovery and verification side, but every critical finding is verified by a human expert.

How findings are reported

Every finding is presented with an executable proof of concept and step-by-step reproduction; false positives are eliminated. For this discipline see verified vulnerabilities and false-positive-free testing. The report includes a risk rating, impact and a clear remediation step for each vulnerability; closure is confirmed with a retest after remediation.

Frequently Asked Questions

Is a scanner report a penetration test? No. Automated scanning is part of the test; only manual testing and human verification reveal business-logic and authorization flaws.

Is it tested in production? Preferably on a copy environment; if production must be tested, scope, time window and data handling are defined in writing, and KVKK obligations are observed for tests touching personal data.

How often should it be done? At least once a year and after significant application changes; more often for teams doing continuous delivery.

Sources

To manually test your web application's business logic and authorization layer, contact DSET.