Try the following code. The value you are looking for is stored on a GuidAttribute instance attached to the Assembly

using System.Runtime.InteropServices;

static void Main(string[] args)
{
    var assembly = typeof(Program).Assembly;
    var attribute = (GuidAttribute)assembly.GetCustomAttributes(typeof(GuidAttribute),true)[0];
    var id = attribute.Value;
    Console.WriteLine(id);
}