Get ASP.NET auth cookie for site with CSRF protection enabled using PowerShell

GetCookie.ps1

function Get-SessionCookie($url,$username,$password,$cookieName)
{
    $loginResponse = Invoke-WebRequest $url -SessionVariable ws -UseBasicParsing
    $requestVerificationToken  = ($loginResponse.InputFields | Where { $_.name -eq "__RequestVerificationToken" }).value
    $body = @{
        "__RequestVerificationToken" = $requestVerificationToken;
        "UserName" = $username;
        "Password" = $password;
    }
    $loggedInResponse = Invoke-WebRequest $url -Body $body -Method POST -WebSession $ws -UseBasicParsing

    return $ws.Cookies.GetCookies($url)[$cookieName].ToString()
}

$cookie = Get-SessionCookie "https://somesite.com/login" "me@me.com" "password" ".ASPXAUTH"
# cookie now contains .ASPXAUTH=xxxxxxx