A problem linking my .obj File With ALink

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Jesse Redick

Joined: 11 Jan 2011
Posts: 15

Jesse Redick 12 Jan 2011, 17:27

Hello again,

Sorry, but I have another problem. It seems I can't get my .obj file to compile in Alink. Here is my code:

Code:

format ms coff

extrn '__imp__ShellExecuteA@24' as ShellExecute:dword

section '.text' code readable executable

public Shell

Shell:

push    5
push       0
push       0
push       a
push       0
push       0
call   [ShellExecute]
ret

section '.data' data readable writeable

a db 'notepad',0

FASM turns it into an object file just fine. The problem is with Alinker. When I try to compile it like this:

Code:

alink.exe -oPE -subsys gui Shell.obj

I get an "Unresolved external __imp__ShellExecuteA@24" error. Can anyone tell me what the problem is? Thanks again for your time.

12 Jan 2011, 17:27

guignol

Joined: 06 Dec 2008
Posts: 761

guignol 12 Jan 2011, 17:35

Where is your ShellExecute?

12 Jan 2011, 17:35

Jesse Redick

Joined: 11 Jan 2011
Posts: 15

Jesse Redick 12 Jan 2011, 17:39

guignol wrote:

Where is your ShellExecute?

Not sure I understand the question Confused

. I am fairly new at this. I think I am calling ShellExecute correctly?

12 Jan 2011, 17:39

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20760
Location: In your JS exploiting you and your system

revolution 12 Jan 2011, 17:43

Have you told Alink where to find "__imp__ShellExecuteA@24"? Which object file defines "__imp__ShellExecuteA@24"?

12 Jan 2011, 17:43

guignol

Joined: 06 Dec 2008
Posts: 761

guignol 12 Jan 2011, 17:45

Where's the address labeled ShellExecute which you try to call?

12 Jan 2011, 17:45

Jesse Redick

Joined: 11 Jan 2011
Posts: 15

Jesse Redick 12 Jan 2011, 17:47

revolution wrote:

Have you told Alink where to find "__imp__ShellExecuteA@24"? Which object file defines "__imp__ShellExecuteA@24"?

Ah, no I did not. I was using the MS Coff demo from the FASM package as my base and so I didn't know had to do that. How would I go about telling Alink where it is?

12 Jan 2011, 17:47

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20760
Location: In your JS exploiting you and your system

revolution 12 Jan 2011, 17:48

guignol wrote:

Where's the address labeled ShellExecute which you try to call?

It has been aliased to __imp__ShellExecuteA@24 with the extrn directive.

12 Jan 2011, 17:48

Jesse Redick

Joined: 11 Jan 2011
Posts: 15

Jesse Redick 12 Jan 2011, 17:48

guignol wrote:

Where's the address labeled ShellExecute which you try to call?

I will be trying to figure that out now Smile

12 Jan 2011, 17:48

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20760
Location: In your JS exploiting you and your system

revolution 12 Jan 2011, 17:51

Jesse Redick wrote:

revolution wrote:
Have you told Alink where to find "__imp__ShellExecuteA@24"? Which object file defines "__imp__ShellExecuteA@24"?

Ah, no I did not. I was using the MS Coff demo from the FASM package as my base and so I didn't know had to do that. How would I go about telling Alink where it is?

It is probably in a library file somewhere that came with Alink. Do you have other examples that come with Alink to show how to link things to the Windows API?

12 Jan 2011, 17:51

Jesse Redick

Joined: 11 Jan 2011
Posts: 15

Jesse Redick 12 Jan 2011, 17:56

revolution wrote:

Jesse Redick wrote:

revolution wrote:
Have you told Alink where to find "__imp__ShellExecuteA@24"? Which object file defines "__imp__ShellExecuteA@24"?

Ah, no I did not. I was using the MS Coff demo from the FASM package as my base and so I didn't know had to do that. How would I go about telling Alink where it is?
It is probably in a library file somewhere that came with Alink. Do you have other examples that come with Alink to show how to link things to the Windows API?

Yes I do, but they all are for NASM. I do understand what you are saying though Smile

. Looks like I will have to work on this a bit more.

12 Jan 2011, 17:56

Jesse Redick

Joined: 11 Jan 2011
Posts: 15

Jesse Redick 12 Jan 2011, 18:32

Well everyone,

I had thought I was close. The example that Alink gives for Coff files seems to need NASM syntax. Alink doesn't seem to want to compile an .obj file made with FASM syntax. I tried everything!

I will just have to find another linker instead. Thanks for putting me on the right path though revolution and guignol Smile

12 Jan 2011, 18:32

ProphetOfDoom

Joined: 08 Aug 2008
Posts: 120
Location: UK

ProphetOfDoom 12 Jan 2011, 21:08

Hi,

I've been using GoLink to link my Fasm programs.

http://www.godevtool.com/

It has good documentation. You just need to provide it with a text file telling it what system .dlls to link to (Shell32.dll I think, in your case).

12 Jan 2011, 21:08

Jesse Redick

Joined: 11 Jan 2011
Posts: 15

Jesse Redick 12 Jan 2011, 23:20

ProphetOfDoom wrote:

Hi,

I've been using GoLink to link my Fasm programs.

http://www.godevtool.com/

It has good documentation. You just need to provide it with a text file telling it what system .dlls to link to (Shell32.dll I think, in your case).

ProphetOfDoom,

Wow thanks so much! I have been looking for a working linker all day and this one worked. Thank you again! Smile

12 Jan 2011, 23:20

ProphetOfDoom

Joined: 08 Aug 2008
Posts: 120
Location: UK

ProphetOfDoom 13 Jan 2011, 01:18

You're welcome Smile

Glad to have helped.

13 Jan 2011, 01:18

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