Web Application Penetration Testing: A Comprehensive Guide

Web Application Penetration Testing, often referred to as “Pentesting,” is a method of identifying, analyzing, and reporting vulnerabilities in a web application. These vulnerabilities may include buffer overflow, input validation, code execution, bypass authentication, SQL Injection, CSRF, and cross-site scripting. This article provides a detailed checklist for conducting such testing.

Information Gathering

1. Retrieve and Analyze robot.txt files: Use tools like GNU Wget to analyze these files.
2. Examine software version and database details: Request invalid pages to identify technical components and bugs via error codes.
3. Implement DNS techniques: Use DNS inverse queries, DNS zone transfers, and web-based DNS searches.
4. Perform directory-style searching and vulnerability scanning: Use tools like NMAP and Nessus to probe for URLs.
5. Identify the application’s entry point: Use tools like Burp Proxy, OWSAP ZAP, TemperIE, and WebscarabTemper Data.
6. Perform TCP/ICMP and service fingerprinting: Use traditional fingerprint tools like Nmap and Amap.
7. Test for recognized file types/Extensions/Directories: Request common file extensions such as .ASP, .EXE, .HTML, .PHP.
8. Examine the source code: Access the application’s front-end pages to examine the source code.

Authentication Testing

1. Session reuse and automatic logout: Check if the session can be reused after logout and if the application logs out after a period of user inactivity.
2. Browser cache: Check if any sensitive information remains stored in the browser cache.
3. Password reset: Attempt to reset the password through social engineering, secretive question cracking, and guessing.
4. “Remember my password” mechanism: Check the HTML code of the login page to see if this mechanism is implemented.
5. Hardware devices communication: Check if hardware devices communicate directly and independently with the authentication infrastructure.
6. CAPTCHA: Test for any authentication vulnerabilities in the CAPTCHA.
7. Security questions/Answers: Check for any weak security questions or answers.

SQL Injection

A successful SQL injection could lead to the loss of customer trust and allow attackers to steal sensitive information. Implementing a web application firewall can filter out malicious SQL queries in the traffic.

1. Role and Privilege Manipulation: Test to see if resources can be accessed.
2. Path Traversal: Perform input vector enumeration and analyze the input validation functions in the web application.
3. Cookie and Parameter Tampering: Use web spider tools to test for these vulnerabilities.
4. HTTP Request Tampering: Check if it’s possible to gain illegal access to reserved resources.

Configuration Management Testing

1. Directory and File Enumeration: Review server and application documentation, infrastructure, and application admin interfaces.
2. Web server banner and network scanning: Analyze the web server banner and perform network scanning.
3. Old Documentation and Backup: Check for the presence of old documentation and backup files like source codes, passwords, and installation paths.
4. SSL/TLS services: Identify the ports associated with these services using NMAP and NESSUS.
5. OPTIONS HTTP method: Review this method using Netcat and Telnet.
6. HTTP methods and XST: Test for credentials of legitimate users.
7. Application configuration management test: Review the information of the source code, log files, and default error codes.

Session Management Testing

1. Cross-Site Request Forgery (CSRF): Check the URLs in the restricted area.
2. Exposed Session Variables: Inspect encryption and reuse of session token, proxies, andcaching, GET&POST.
3. Cookie Analysis: Collect a sufficient number of cookie samples and analyze the cookie sample algorithm to forge a valid cookie for an attack.
4. Cookie Attribute Testing: Use intercept proxies such as Burp Proxy, OWASP ZAP, or traffic intercept proxies like Temper Data.
5. Session Fixation: Test this to avoid stealing the user session, a process known as session hijacking.

Data Validation Testing

1. JavaScript Coding Errors: Perform source code analysis for these errors.
2. SQL Injection Testing: Perform union query SQL injection testing, standard SQL injection testing, and blind SQL query testing using tools like sqlninja, sqldumper, and SQL power injector.
3. Cross-Site Scripting (XSS): Analyze the HTML code, test for stored XSS, and leverage stored XSS using tools like XSS proxy, Backframe, Burp Proxy, OWASP ZAP, and XSS Assistant.
4. LDAP Injection Testing: Perform this to access sensitive information about users and hosts.
5. IMAP/SMTP Injection Testing: Perform this to access the backend mail server.
6. XPATH Injection Testing: Perform this to access confidential information.
7. XML Injection Testing: Perform this to know information about XML structure.
8. Code Injection Testing: Perform this to identify input validation errors.
9. Buffer Overflow Testing: Perform this for stack and heap memory information and application control flow.
10. HTTP Splitting and Smuggling: Test for cookies and HTTP redirect information.

Denial of Service Testing

1. Large Number of Requests: Send a large number of requests that perform database operations and observe any slowdown and new error messages.
2. Manual Source Code Analysis: Submit a range of input varying lengths to the applications.
3. SQL Wildcard Attacks: Test for application information testing.
4. User Specifies Object Allocation: Test whether a maximum number of objects that the application can handle.
5. Extreme Large Number of Input Field: Enter an extremely large number of the input field used by the application as a loop counter.
6. Automated Long Value Submission: Use a script to automatically submit an extremely long value for the server to log the request.

In conclusion, web application penetration testing is a critical aspect of maintaining the security and integrity of any web application. By following this comprehensive checklist, you can ensure that your application is secure from most common vulnerabilities and attacks.