Applications represent the most common avenue for users, customers, and attackers to access data, which means you must build the software to enforce the security policy and to ensure compliance with regulations, including the privacy and integrity of both data and system processes. Regardless of the development model, the application must validate all input. Certain attacks can take advantage of weak validation. One such attack provides script code that causes a trusted user who views the input script to send malicious commands to a web server. What is this called?