C# Program that get's it's PEB (Process Environment Table).

PebWalker.cs

    public static class PebWalker
    {
        public static IntPtr GetPeb()
        {
            IntPtr handle = OpenProcess(0x1040, false, Process.GetCurrentProcess().Id);
            if (handle == IntPtr.Zero) throw new Win32Exception(Marshal.GetLastWin32Error());
            int hr;
            if (IntPtr.Size != 8)
            {
                IntPtr peb32 = new IntPtr();
                hr = NtQueryInformationProcess(handle, 26, ref peb32, IntPtr.Size, IntPtr.Zero);
                CloseHandle(handle);
                if (hr != 0) throw new Win32Exception(hr);
                return peb32;
            }
            PROCESS_BASIC_INFORMATION pbi = new PROCESS_BASIC_INFORMATION();
            hr = NtQueryInformationProcess(handle, 0, ref pbi, 48, IntPtr.Zero);
            CloseHandle(handle);
            if (hr != 0) throw new Win32Exception(hr);
            return pbi.PebBaseAddress;
        }
        [StructLayout(LayoutKind.Sequential)]
        private struct PROCESS_BASIC_INFORMATION
        {
            private readonly IntPtr Reserved1;
            public  readonly IntPtr PebBaseAddress;
        }
        [DllImport("ntdll.dll", SetLastError = true)]
        private static extern int NtQueryInformationProcess(IntPtr ProcessHandle, int ProcessInformationClass, ref PROCESS_BASIC_INFORMATION ProcessInformation, int ProcessInformationLength, IntPtr ReturnLength);
        [DllImport("ntdll.dll", SetLastError = true)]
        private static extern int NtQueryInformationProcess(IntPtr ProcessHandle, int ProcessInformationClass, ref IntPtr ProcessInformation, int ProcessInformationLength, IntPtr ReturnLength);
        [DllImport("kernel32.dll", SetLastError = true)]
        private static extern IntPtr OpenProcess(int dwDesiredAccess, bool bInheritHandle, int dwProcessId);
        [DllImport("kernel32.dll", SetLastError = true)]
        private static extern bool CloseHandle(IntPtr hObject);
    }