[Pericles]

Hola, lo aconsejable seria crear un Stream con los datos y bajarlos en un archivo temporal para ejecutarlo(luego se elimina)
De otra manera es un problema por el tema de seguridad de los sistemas operativos entre otras cosas(ademas de ser una tarea ardua de realizar)

Estuve revisando bastante... encontre esta clase.. y probe con la siguiente llamada.. pero solo problemas! jaja
creo que es muy complicado y no tiene mucho sentido (quizas exista algun requerimiento lo exija? ya seria casi como programar un virus.. no será para eso? jajaj)

Código Delphi [-]
{
  Unit Name: 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: security.org.sg/code/loadexe.html
  Release Date: 26th August 2009
  Website: hackhound.org
  History: First try
}

unit uExecFromMem;

interface

uses Windows;

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

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

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

implementation

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(DWORD(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(DWORD(pImage) + IDH^._lfanew + 248 + i * 40);
    CopyMemory(Pointer(DWORD(Result) + ISH^.VirtualAddress), Pointer(DWORD(pImage) + ISH^.PointerToRawData), ISH^.SizeOfRawData);
  end;
end;

function ExecuteFromMem(szFilePath:string; pFile:Pointer)WORD;
var
  PI:           TProcessInformation;
  SI:           TStartupInfo;
  CT:           TContext;
  IDH:          PImageDosHeader;
  INH:          PImageNtHeaders;
  dwImageBase:  DWORD;
  pModule:      Pointer;
  dwNull:       DWORD;
begin
  Result := 0;
  IDH := pFile;
  if IDH^.e_magic = IMAGE_DOS_SIGNATURE then
  begin
    INH := Pointer(DWORD(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(nil, PChar(szFilePath), nil, nil, FALSE, CREATE_SUSPENDED, nil, nil, SI, PI) 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(DWORD(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);
            FreeMem(pFile, INH^.OptionalHeader.SizeOfImage);
            Result := PI.hThread;
          end;
        end;
      end;
    end;
  end;
end;

end.

Código Delphi [-]

procedure TForm1.Button1Click(Sender: TObject);
var
 ms:TMemoryStream;

begin

  ms:=TMemoryStream.Create;
  TBlobField(ADOQuery1archivos).SaveToStream(ms);
  ms.Position := 0;

  // ?????
//ExecuteFromMem(Application.ExeName,'',ms.Memory); // pointing to an existing executable

ExecuteFromMem(Application.ExeName,ms.Memory); // pointing to an existing executable

  //prueba de bajada a archivo para ver si se grabo correctamente y funciona...
  //ms.SaveToFile('c:\prueba.exe');
  //winexec('c:\prueba.exe',SW_SHOWNORMAL);

  ms.Free;
 end;

Saludos
Nicolas Perichon