Performs systematic security testing of web applications following the OWASP Web Security Testing Guide (WSTG) methodology to identify vulnerabilities in authentication, authorization, input validation, session management, and business logic. The tester uses Burp Suite as the primary interception proxy alongside manual testing techniques to find flaws that automated scanners miss. Activates for requests involving web app pentest, OWASP testing, application security assessment, or web vulnerability testing.
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name
performing-web-application-penetration-test
description
Performs systematic security testing of web applications following the OWASP Web Security Testing Guide (WSTG) methodology to identify vulnerabilities in authentication, authorization, input validation, session management, and business logic. The tester uses Burp Suite as the primary interception proxy alongside manual testing techniques to find flaws that automated scanners miss. Activates for requests involving web app pentest, OWASP testing, application security assessment, or web vulnerability testing.
Validating remediation of previously identified web application vulnerabilities during retesting
Assessing third-party web applications before integration into the organization's environment
Evaluating custom-developed web applications where automated scanning alone is insufficient
Do not use against web applications without written authorization, against production systems during peak traffic hours without explicit approval, or for denial-of-service testing of web infrastructure.
Prerequisites
Signed statement of work (SoW) defining the target application URLs, environments (staging/production), and testing boundaries
Burp Suite Professional license with up-to-date extensions (Active Scan++, Autorize, JSON Beautifier, Logger++)
Valid test accounts at each privilege level (unauthenticated, standard user, administrator) for authorization testing
Application documentation including API specifications (OpenAPI/Swagger), sitemap, and technology stack details
Browser configured with Burp Suite proxy (FoxyProxy recommended) and Burp CA certificate installed
Workflow
Step 1: Reconnaissance and Application Mapping
Map the entire attack surface of the web application:
Configure Burp Suite proxy and spider the application by browsing every page, form, and function manually while Burp captures the sitemap
Use Burp's Discover Content feature to find hidden directories and files not linked from the visible application
Identify the technology stack from response headers (X-Powered-By, Server), cookies (JSESSIONID = Java, PHPSESSID = PHP, ASP.NET_SessionId = .NET), and page extensions
Enumerate endpoints using ffuf -w /usr/share/seclists/Discovery/Web-Content/directory-list-2.3-medium.txt -u https://target.com/FUZZ -mc 200,301,302,403
Review JavaScript files for hardcoded API endpoints, secrets, and client-side routing using Burp's JS Link Finder extension or LinkFinder.py
Document all entry points: URL parameters, POST bodies, HTTP headers, cookies, file uploads, and WebSocket connections
Step 2: Authentication Testing
Test authentication mechanisms for weaknesses:
Credential enumeration: Submit valid and invalid usernames to identify differences in response (timing, message, HTTP status) that reveal valid accounts
Brute force protection: Attempt 10-20 rapid login attempts with invalid credentials to verify account lockout and rate limiting are enforced
Password policy: Test password creation with weak passwords (123456, password, single character) to verify policy enforcement
Multi-factor authentication bypass: Test for MFA bypass by directly accessing post-authentication pages, manipulating MFA tokens, or replaying successful MFA responses
Session fixation: Note the session token before and after authentication. If the token does not change after login, session fixation is possible
Remember me functionality: Inspect persistent authentication tokens for predictability, encryption, and proper expiration
Password reset: Test the password reset flow for token predictability, token expiration, account enumeration via the reset form, and host header injection
Step 3: Authorization Testing
Verify that access controls are properly enforced:
Horizontal privilege escalation (IDOR): Using Account A, capture requests that access Account A's resources. Replay those requests substituting Account B's identifiers (user IDs, order numbers, filenames). Use Burp's Autorize extension to automate this across all endpoints.
Vertical privilege escalation: Using a low-privilege account, attempt to access administrative functions by directly browsing to admin URLs, modifying role parameters in requests, or manipulating JWT claims
Forced browsing: Attempt to access resources that should require authentication by directly navigating to internal URLs collected during mapping
HTTP method tampering: If GET is blocked on an endpoint, try PUT, POST, DELETE, PATCH, or use method override headers (X-HTTP-Method-Override: DELETE)
Path traversal in authorization: Test URL path manipulation (/api/users/123/../456/profile) to bypass path-based authorization checks
Step 4: Input Validation and Injection Testing
Test all input points for injection vulnerabilities:
SQL injection: Insert payloads like ' OR 1=1--, ' UNION SELECT NULL,NULL--, and time-based blind payloads ('; WAITFOR DELAY '0:0:5'--) into every parameter. Use sqlmap for automated detection and exploitation of confirmed injection points.
Cross-Site Scripting (XSS): Test reflected, stored, and DOM-based XSS with payloads like <script>alert(document.domain)</script>, "><img src=x onerror=alert(1)>, and event handlers. Test in all contexts: HTML body, attributes, JavaScript, and URLs.
Server-Side Request Forgery (SSRF): Supply internal URLs (http://169.254.169.254/latest/meta-data/, http://127.0.0.1:6379/) in parameters that fetch external resources (webhooks, image URLs, import functions)
Command injection: Insert OS command separators (;, |, &&, `) followed by commands (id, whoami, ping -c 3 collaborator.net) in parameters processed by the server
XML External Entity (XXE): Submit XML payloads with external entity declarations (<!DOCTYPE foo [<!ENTITY xxe SYSTEM "file:///etc/passwd">]>) in XML upload or API endpoints
Server-Side Template Injection (SSTI): Test with {{7*7}}, ${7*7}, <%= 7*7 %> in parameters rendered by template engines
Step 5: Session Management Testing
Evaluate the security of session handling:
Session token analysis: Collect 100+ session tokens and analyze for randomness using Burp Sequencer. Check token length (minimum 128 bits of entropy), character set, and predictability.
Session expiration: Verify that sessions expire after a defined idle timeout and absolute timeout. Test by capturing a session token, waiting beyond the timeout, and replaying.
Cookie security flags: Verify Secure, HttpOnly, and SameSite flags are set on session cookies. Missing HttpOnly enables XSS-based session theft. Missing SameSite enables CSRF.
CSRF testing: Identify state-changing operations (password change, email update, fund transfer) and test if they can be triggered from a cross-origin page without a valid CSRF token
Concurrent session handling: Test if the application limits the number of concurrent sessions and if logging in from a new location invalidates the previous session
Step 6: Business Logic Testing
Test application-specific logic flaws that automated scanners cannot detect:
Workflow bypass: Attempt to skip steps in multi-step processes (checkout, registration, approval) by directly requesting later-stage endpoints
Numeric manipulation: Modify prices, quantities, or amounts to negative values, zero, or extremely large numbers to test for integer overflow or logic errors
File upload bypass: Test file upload restrictions by modifying MIME types, double extensions (file.php.jpg), null bytes (file.php%00.jpg), and content-type manipulation
Step 7: Report and Remediation Guidance
Compile all findings into a structured report:
Write an executive summary describing the overall application security posture in business terms
Document each finding with title, severity (CVSS 3.1), affected URL/parameter, description, reproduction steps, screenshots, and HTTP request/response pairs from Burp
Provide specific remediation guidance for each finding including code-level fixes where applicable
Include a risk matrix showing the distribution of findings by severity
Deliver the report securely (encrypted, not via email attachment) and schedule a findings walkthrough with the development team
Key Concepts
Term
Definition
OWASP WSTG
The Web Security Testing Guide; a comprehensive open-source guide to testing web application security organized by test category (authentication, authorization, input validation, etc.)
IDOR
Insecure Direct Object Reference; a vulnerability where the application exposes internal object identifiers and fails to verify the requesting user is authorized to access that object
CSRF
Cross-Site Request Forgery; an attack that forces an authenticated user's browser to send a forged request to a vulnerable web application
Session Fixation
An attack where the attacker sets a user's session ID to a known value before the user authenticates, then hijacks the session after login
Forced Browsing
Attempting to access application resources by directly requesting URLs not linked from the visible application, bypassing intended access controls
SSTI
Server-Side Template Injection; injecting template directives into server-side template engines to achieve remote code execution
Tools & Systems
Burp Suite Professional: Primary web application testing proxy providing interception, scanning, and manual testing tools including Repeater, Intruder, and Sequencer
ffuf: Fast web fuzzer for directory/file discovery, parameter fuzzing, and virtual host enumeration
sqlmap: Automated SQL injection detection and exploitation tool supporting all major database engines and injection techniques
Nuclei: Template-based vulnerability scanner with community-maintained templates for known CVEs and misconfigurations
SecLists: Curated collection of wordlists for fuzzing, credential testing, and payload delivery used throughout web application testing
Context: A retail company is launching a new e-commerce platform built on Node.js with a React frontend and PostgreSQL database. The application handles credit card payments through Stripe integration and stores customer PII. Testing scope includes the staging environment with full API access.
Approach:
Map the application through manual browsing and API documentation review, identifying 47 unique endpoints
Test authentication flows including social login (OAuth), standard login, and password reset
Discover IDOR vulnerability in the order retrieval API (/api/orders/{orderId}) where any authenticated user can view any order by iterating order IDs
Identify stored XSS in the product review feature that executes when administrators view the admin dashboard
Find SSRF in the product image import function that allows reading AWS EC2 instance metadata
Test payment logic by manipulating price values in the client-side cart before checkout submission
Report all findings with specific Node.js code-level remediation (parameterized queries, input sanitization with DOMPurify, authorization middleware)
Pitfalls:
Testing only the frontend while ignoring the API layer that lacks independent authorization checks
Missing business logic flaws by relying solely on automated scanning without manual testing
Not testing the same functionality across different privilege levels to catch authorization issues
Overlooking client-side JavaScript for hardcoded API keys, debug endpoints, and internal URLs
Output Format
## Finding: Insecure Direct Object Reference in Order API
**ID**: WEB-003
**Severity**: High (CVSS 7.5)
**Affected URL**: GET /api/v1/orders/{orderId}
**Parameter**: orderId (path parameter)
**Description**:
The order retrieval endpoint does not verify that the authenticated user owns
the requested order. Any authenticated user can access any order's details
including customer name, shipping address, email, phone number, and order
items by incrementing the orderId path parameter.
**Reproduction Steps**:
1. Authenticate as user A (testuser@example.com)
2. Note user A's order ID: 10451
3. Send GET /api/v1/orders/10452 with user A's session token
4. Observe that user B's order details are returned with full PII
**HTTP Request**:
GET /api/v1/orders/10452 HTTP/1.1
Host: staging.example.com
Authorization: Bearer eyJhbGc....[User A's token]
**HTTP Response** (truncated):
HTTP/1.1 200 OK
{"orderId":10452,"customerName":"Jane Smith","email":"jane@...","address":"123 Main St"}
**Impact**:
An attacker can enumerate all customer orders and extract PII (names, emails,
addresses, phone numbers) for an estimated 25,000 customers.
**Remediation**:
Add authorization middleware that verifies the authenticated user's ID matches
the order's userId field before returning order data. Implement UUIDs instead
of sequential integers for order identifiers to prevent enumeration.
