using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Security.Principal;
using System.IO;

namespace ConsoleApplication2
{
    class Program
    {
        static void Main(string[] args)
        {
            string username = @"Abservr.ivanov"; // Нужно чтобы соединялось и через домен и без.
            string password = @"Blab";
            string network_file_path = @"\172.10.0.80c$testtest.txt";
            string local_file_path = @"c:testtest.txt";
            AppDomain.CurrentDomain.SetPrincipalPolicy(PrincipalPolicy.WindowsPrincipal);
            WindowsIdentity idnt = new WindowsIdentity(username, password);
            WindowsImpersonationContext context = idnt.Impersonate();
            File.Copy(network_file_path, local_file_path, true);
            context.Undo();
        }
    }
}
`