The account select option is read directly and provided in a message back to the backend system without validating the account number if one of the accounts provided by the backend system.An attacker can change the HTML in any way they choose: rather than account names.Unless the business will allow updating "bad" regexes on a daily basis and support someone to research new attacks regularly, this approach will be obviated before long.Rather than accept or reject input, another option is to change the user input into an acceptable format Any characters which are not part of an approved list can be removed, encoded or replaced.
Detecting attempts to find these weaknesses is a critical protection mechanism.
int payee Lst Id = Parameter('payeelstid'); account From = Acct Number By Index(payee Lst Id); Not only is this easier to render in HTML, it makes validation and business rule validation trivial. To provide defense in depth and to prevent attack payloads from trust boundaries, such as backend hosts, which are probably incapable of handling arbitrary input data, business rule validation is to be performed (preferably in workflow or command patterns), even if it is known that the back end code performs business rule validation.
This is not to say that the entire set of business rules need be applied - it means that the fundamentals are performed to prevent unnecessary round trips to the backend and to prevent the backend from receiving most tampered data.
Add this dependency to your // E.g this contract require("This message is bad", contains String("good")); // Will yield this error org.valid4j.exceptions.
Require Violation: expected: a string containing "good" but: was "This message is bad" // E.g this validation validate("This message is bad", contains String("good"), Illegal Argument Exception.class); // Will yield this exception with message // (NOTE: Exception class must accept one String argument in constructor for this feature to be supported)