Which tool should an application developer use to help identify input validation vulnerabilities?

An application developer should use a tool known as a Static Application Security Testing (SAST) tool to help identify input validation vulnerabilities. Here are the steps:

1. Choose a SAST tool: There are many SAST tools available in the market, both open-source and commercial. Some popular ones include SonarQube, Veracode, Checkmarx, etc. The choice of tool depends on the specific requirements of the project and the programming language used.

2. Set up the tool: Once the tool is chosen, it needs to be set up. This usually involves installing the tool, configuring it to scan the codebase, and setting up any necessary integrations with other tools or systems.

3. Run the tool: After the setup, the tool can be run to scan the codebase. This will generate a report of potential vulnerabilities, including input validation issues.

4. Analyze the results: The report generated by the tool needs to be analyzed to identify the actual vulnerabilities. This usually involves reviewing the code where the potential vulnerability is reported and determining if it is a real issue.

5. Fix the vulnerabilities: Once the vulnerabilities are identified, they need to be fixed. This usually involves modifying the code to handle the input validation properly.

6. Repeat the process: The process of running the tool, analyzing the results, and fixing the vulnerabilities should be repeated regularly to ensure that new vulnerabilities are not introduced as the codebase evolves.