ASVS V5 Input validation and output encoding

Control Objective
The most common web application security weakness is the failure to properly validate input coming from the client or from the environment before using it. This weakness leads to almost all of the major vulnerabilities in web applications, such as cross site scripting, SQL injection, interpreter injection, locale/Unicode attacks, file system attacks, and buffer overflows.

Ensure that a verified application satisfies the following high level requirements:


 * All input is validated to be correct and fit for the intended purpose.
 * Data from an external entity or client should never be trusted and should be handled accordingly.