:link-with-uscores1: https://www.owasp.org/index.php/Cross-Site_Request_Forgery_(CSRF)_Prevention_Cheat_Sheet
:link-with-uscores2: https://www.owasp.org/index.php/XSS_(Cross_Site_Scripting)_Prevention_Cheat_Sheet

== Recommended Secure Coding Practices

Never trust any part of the request to be safe. Make sure that the URI, header and body are properly https://www.owasp.org/index.php/Input_Validation_Cheat_Sheet[sanitized] before being used. Their content, length, encoding, name (ex: name of URL query parameters) should be checked. Validate that the values are in a predefined whitelist. The opposite, i.e. searching for dangerous values in a given input, can easily miss some of them.


Do not rely solely on cookies when you implement your authentication and permission logic. Use additional protections such as   {link-with-uscores1}[CSRF] tokens when possible.


Do not expose sensitive information in your response. If the endpoint serves files, limit the access to a dedicated directory. https://cheatsheetseries.owasp.org/cheatsheets/Session_Management_Cheat_Sheet.html#cookies[Protect your sensitive cookies] so that client-side javascript cannot read or modify them.


Sanitize all values before returning them in a response, be it in the body, header or status code. Special care should be taken to avoid the following attacks:

* {link-with-uscores2}[Cross-site Scripting (XSS)], which happens when an unsafe value is included in an HTML page.
* https://www.owasp.org/index.php/Unvalidated_Redirects_and_Forwards_Cheat_Sheet[Unvalidated redirects] which can happen when the ``++Location++`` header is compromised.

Restrict security-sensitive actions, such as file upload, to authenticated users.


Be careful when errors are returned to the client, as they can provide sensitive information. Use 404 (Not Found) instead of 403 (Forbidden) when the existence of a resource is sensitive.
