Validating required fields
For example, if you use HTML entity encoding on user input before it is sent to a browser, it will prevent most XSS attacks.However, simply preventing attacks is not enough - you must perform Intrusion Detection in your applications.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.Here are some examples: If you expect a phone number, you can strip out all non-digit characters.
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.
This is a dangerous strategy, because the set of possible bad data is potentially infinite.
Adopting this strategy means that you will have to maintain the list of "known bad" characters and patterns forever, and you will by definition have incomplete protection.
To ensure that the application is robust against all forms of input data, whether obtained from the user, infrastructure, external entities or database systems. This weakness leads to almost all of the major vulnerabilities in applications, such as Interpreter Injection, locale/Unicode attacks, file system attacks and buffer overflows.
All sections should be reviewed The most common web application security weakness is the failure to properly validate input from the client or environment.
If you want text from a user comment form, it is difficult to decide on a legitimate set of characters because nearly every character has a legitimate use.