use Windows API InternetGetCookies:
[DllImport("Wininet.dll", CharSet=CharSet.Auto, SetLastError=true)]
public static extern bool InternetGetCookie(string lpszUrlName, string lpszCookieName, [Out] StringBuilder lpszCookieData, [MarshalAs(UnmanagedType.U4)] out int lpdwSize);
Usage:
StringBuilder result = new StringBuilder(1000, 4096);
int size = 1000;
if (InternetGetCookie("http://community.csdn.net", null, result, out size))
{
Console.WriteLine(result);
}