您可以使用Windows API LogonUser函数。

[DllImport("advapi32.dll", SetLastError = true, BestFitMapping = false, ThrowOnUnmappableChar = true)]
[return: MarshalAs(UnmanagedType.Bool)]
internal static extern bool LogonUser(
[MarshalAs(UnmanagedType.LPStr)] string pszUserName,
[MarshalAs(UnmanagedType.LPStr)] string pszDomain,
[MarshalAs(UnmanagedType.LPStr)] string pszPassword,
int dwLogonType,
int dwLogonProvider,
ref IntPtr phToken);

[DllImport("kernel32.dll")]
private static extern bool CloseHandle(IntPtr hObject);

public static void Main(string[] args)
{
    var domain = "...";
    var user = "...";
    var pwd = "...";
    var token = new IntPtr();
    var success = false;
    try
    {
        success = LogonUser(user, domain, pwd, 2/*LOGON32_LOGON_INTERACTIVE*/, 0, ref token);
    }
    finally
    {
        CloseHandle(token);
    }
}

根据您的要求，您可能需要使用CredUIPromptForCredentials。