IIST-SV-000137 - The production IIS 10.0 web server must utilize SHA2 encryption for the Machine Key - Encryption Method
The Machine Key element of the ASP.NET web.config specifies the algorithm and keys that ASP.NET will use for encryption. The Machine Key feature can be managed to specify hashing and encryption settings for application services such as view state, forms authentication, membership and roles, and anonymous identification. Ensuring a strong encryption method can mitigate the risk of data tampering in crucial functional areas such as forms authentication cookies, or view state.
Open the IIS 10.0 Manager. Click the IIS 10.0 web server name. Double-click the 'Machine Key' icon in the web server Home Pane. Set the Validation method to 'HMACSHA256' or stronger. Set the Encryption method to 'Auto'. Click 'Apply' in the 'Actions' pane.