Input validation is performed to ensure only properly formed data is entering the workflow in an information system, preventing malformed data from persisting in the database and triggering malfunction of various downstream components.Input validation should happen as early as possible in the data flow, preferably as soon as the data is received from the external party.
Input Validation should not be used as the primary method of preventing XSS, SQL Injection and other attacks which are covered in respective cheat sheets but can significantly contribute to reducing their impact if implemented properly.To normalise an email address input, you would convert the domain part ONLY to lowercase.Unfortunately this does and will make input harder to normalise and correctly match to a users intent.Standalone applications typically have a main window that both displays the main data over which the application operates and exposes the functionality to process that data through user interface (UI) mechanisms like menu bars, tool bars, and status bars.A non-trivial application may also display additional windows to do the following: dialog box is displayed by a function when the function needs additional data from a user to continue.Input validation should be applied on both syntactical and semantic level.
Syntactic validation should enforce correct syntax of structured fields (e.g.
White list validation is appropriate for all input fields provided by the user.
White list validation involves defining exactly what IS authorized, and by definition, everything else is not authorized.
Recent changes to the landscape mean that the number of false-negatives will increase, particularly due to: To ensure an address is deliverable, the only way to check this is to send the user an email and have the user take action to confirm receipt.
Beyond confirming that the email address is valid and deliverable, this also provides a positive acknowledgement that the user has access to the mailbox and is likely to be authorized to use it.
Because the function depends on the modal dialog box to gather data, the modal dialog box also prevents a user from activating other windows in the application while it remains open.