Testing: Introduction and objectives

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This Chapter describes the OWASP Web Application Penetration testing methodology and explains how to test each vulnerabilities.

What is a Web Application Penetration Testing? A penetration test is a method of evaluating the security of a computer system or network by simulating an attack. A Web Application Penetration Test focuses only on evaluating the security of a web application. The process involves an active analysis of the application for any weaknesses, technical flaws or vulnerabilities. Any security issues that are found will be presented to the system owner together with an assessment of their impact and often with a proposal for mitigation or a technical solution.

What is a vulnerability?

Given an application owns a set of assets (resources of value such as the data in a database or on the file system), a vulnerability is a weakness on a asset that makes a threat possible. So a threat is a potential occurrence that may harm an asset exploiting Vulnerability. A test is an action that tends to show a vulnerability in the application.

Our approach in writing this guide

The OWASP approach is Open and Collaborative: This approach tends to create a defined Testing Methodology that will be: The problems that we want to be addressed are: We think that is important to use a method to test all the know vulnerabilities and document all the the pen test activities. What is the OWASP testing methodology?
 * Open: every security expert can participate with his experience in the project. Everything is free.
 * Collaborative: we usually perform brainstorming before the articles are written. So we can share our ideas and develop a collective vision of the project. That means rough consensus, wider audience and participation.
 * Consistent
 * Reproducible
 * Under quality control
 * Document all
 * Test all

Penetration testing will never be an exact science where a complete list of all possible issues that should be tested can be defined. Indeed, penetration testing is only an appropriate technique for testing the security of web applications under certain circumstances. The goal is to collect all the possible testing techniques, explain them and keep the guide updated. The OWASP Web Application Penetration Testing is based on black box approach. The tester know nothing or a few informations about the application to test. The testing model is like this: The test is divided in 2 phases: https://www.example.com/login/Autentic_Form.html Indicates an authentication form in which the application request a username and a password. The following parameters represent two access points (gates) to the application. http://www.example.com/Appx.jsp?a=1&b=1 In this case the application shows two gates (parameters a and b). All the gates found in this phase represent a point of testing. A spreadsheet with the directory tree of the application and all the access points would be useful for the second phase.
 * Tester: Who performs the testing activities
 * Tools and methodology: The core of this Testing Guide project
 * Application: The black box to test
 * Passive mode: in the passive mode the tester try to understand the application's logic, play with the application, a tool can be user for information gathering and HTTP proxy to observe all the HTTP requests and responses. At the end of this phase the tester should understand all the access points (gates) of the application (e.g. Header HTTP, parameters, cookies). For example the tester could find the following:
 * Active mode: in this phase the tester begin to test using the methodology described in the follow paragraphs.

We have splitted the test in 8 sub-categories:
 * Information Gathering
 * Business logic testing
 * Authentication Testing
 * Session Management Testing
 * Data Validation Testing
 * Denial of Service Testing
 * Web Services Testing
 * AJAX Testing

Here is the list of test that we will explain in the next paragraphs: