What is VIEWSTATEGENERATOR and how is it calculated for Exchange .NET deserialization attacks?

VIEWSTATEGENERATOR is a parameter required for ASP.NET ViewState validation, acting as a page-specific hash. For Exchange, it can be calculated in C# by combining the hash of the application path (e.g., `/ecp`) and the page name (e.g., `default.aspx`). Alternatively, you can obtain it by visiting the page and inspecting the hidden `__VIEWSTATEGENERATOR` field. This value is essential for crafting valid viewstate payloads in tools like ysoserial.net. For more on Windows attack techniques, see Penetration Techniques - Acquisition and Clearing of Windows System File Execution Records.