C-sharp : Asp.net misconfiguration

The view state message authentication check (MAC) is disabled. It can allow an attacker to change the view state.

A message authentication code (MAC) is a short piece of information used to authenticate a message - in other words, to confirm that the message came from the stated sender and has not been changed. The MAC value protects both a message’s data integrity as well as its authenticity. For security purposes, always enable message authentication.