Trying to load an exe from memory not working on Windows 7 64bit

[star-italia]

I'm posting it here even if it is not a kernel question, because I didn't know where else to post.

Hi everyone, I'm trying to start an exe from memory but at the moment

I need this because for a customer we need to crypt the exe and then launch it without decrypting it to disk

The technique I'm trying to use is to create a process in suspended mode and then change the image
of the process with my exe and then resume the thread

I'm stuck at the GetThreadContext function which give me a
87 error (The parameter is incorrect)
Can anyone help me?

Here is the code:

STARTUPINFO si = {0};
PROCESS_INFORMATION pi;

if(CreateProcess(L"calc.exe", NULL,NULL, NULL, 0, CREATE_SUSPENDED, NULL, NULL, &si, pi))
{
CONTEXT ctx;
ctx->ContextFlags=CONTEXT_FULL;
GetThreadContext (pi->hThread, ctx);
GetError ("GetThreadContext");

I've read on MSDN this:

A 64-bit application can retrieve the context of a WOW64 thread using the Wow64GetThreadContext function.

and

WOW64: The handle must also have THREAD_QUERY_INFORMATION access.

And I have two questions:

1) I am using Windows 7 Ultimate x64, but my project is compiled as Win32, and the exe I have to load is 32bit
so: do i have to use GetThreadContext or Wow64GetThreadContext?
2) How do I create a security descriptor with THREAD_QUERY_INFORMATION?

Or if you can point me to some working source code for x64 to study...

Thanks in advance for your help

[Jialiang Ge [MSFT]]

Hello

I performed a test using this code compiled in win32 on x64 Windows 7 RTM.

STARTUPINFO si;
PROCESS_INFORMATION pi;
ZeroMemory( &si, sizeof(si) );
si.cb = sizeof(si);
ZeroMemory( &pi, sizeof(pi) );

if(CreateProcess(L"c:\\windows\\SysWOW64\\calc.exe", NULL, NULL, NULL,
FALSE, CREATE_SUSPENDED,
NULL, NULL, &si, &pi))
// [ or ]
// if(CreateProcess(L"c:\\windows\\system32\\calc.exe", NULL, NULL,
NULL, FALSE, CREATE_SUSPENDED,
// NULL, NULL, &si, &pi))
{
CONTEXT ctx;
ctx.ContextFlags=CONTEXT_FULL;
if (!GetThreadContext(pi.hThread, &ctx))
{
DWORD err = GetLastError();
printf("%d", err);
}
}

I do not get any errors. Could you please let me know your test result?
Should I target the code to x64?

Regards,
Jialiang Ge (jia...@online.microsoft.com, remove 'online.')
Microsoft Online Community Support

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[star-italia]

Thank you, I wasn't doing ZeroMemory on si... but however the code doesn't work,
and I don't know why, because unfortunately is not mine but is a cut and paste
from http://www.security.org.sg/code/loadexe.html

However thank for your help... Do you know if there is some other piece of source code
to try?

Thanks in advance

[Jialiang Ge [MSFT]]

Hello

Do you mean that the code in my last reply does not work on your side? What
error do you see?

[star-italia]

No no, your code works, what doesn't work is the code after that :)

However can you point me to some working code that I can study on how to launch an exe in memory using Win32 API?

Thanks in advance