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GREYSERGING



Joined: 03 Oct 2022
Posts: 4
GREYSERGING 03 Oct 2022, 09:05
Data section:
Code:
boundary db 8 dup (0)
header db 53 dup (0)
send_data dd ?
GetProcessHeapMem dd ?    

At the beginning of the program, I allocate memory to the send_data variable
Code:
invoke GetProcessHeap
mov [GetProcessHeapMem],eax
invoke HeapAlloc,[GetProcessHeapMem],0,1024
mov [send_data],eax    

Then I form a header to send the POST
Code:
invoke memcpy, header, header_no_boundary, 44
invoke memcpy, header + 44, boundary, 8

invoke memcpy, send_data, data1, 2
invoke memcpy, send_data + 2, boundary, 8
...    

And I'm sending it
Code:
invoke HttpSendRequestA, [hora], header, 52, send_data, 110    

The header itself is sent successfully, but send_data is not sent, I cannot allocate send_data fixed memory since the data can be either several kilobytes or hundreds of megobytes, but if I do so
Code:
send_data db 1024 dup (0)    

Then everything went well, I suspect that the problem is in HeapAlloc, but I can't say for sure, so tell me what's the matter?
Post 03 Oct 2022, 09:05
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 18942
Location: In your JS exploiting you and your system
revolution 03 Oct 2022, 09:13
You are using send_data as both a buffer and a pointer.

Try something like this:
Code:
mov ebx.[send_data]
nvoke memcpy, ebx, data1, 2
nvoke memcpy, addr ebx+2, data1, 2
;...
invoke HttpSendRequestA, [hora], header, 52, [send_data], 110    
Post 03 Oct 2022, 09:13
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GREYSERGING



Joined: 03 Oct 2022
Posts: 4
GREYSERGING 03 Oct 2022, 09:19
It didn't help, this is my complete code


Last edited by GREYSERGING on 03 Oct 2022, 09:27; edited 1 time in total
Post 03 Oct 2022, 09:19
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GREYSERGING



Joined: 03 Oct 2022
Posts: 4
GREYSERGING 03 Oct 2022, 09:27
Thank you, everything worked out, I initially misunderstood
Post 03 Oct 2022, 09:27
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Overclick



Joined: 11 Jul 2020
Posts: 587
Location: Ukraine
Overclick 03 Oct 2022, 14:00
You cannot be sure registers still keeping your data after winapi. Also memcpy uses some extra instructions you dont't really need to complete the task. Use movsb(w,d,q) instead.
Code:
macro   memcopy Dest_addr,Source_addr,len
        {
                mov     rdi,Dest_addr
                mov     rsi,Source_addr
                mov     rcx,len
                rep movsb
        }
    

Or even better
Code:
macro   memcopy Dest_addr,Source_addr,len
        {
                mov     rdi,Dest_addr
                mov     rsi,Source_addr
                mov     rcx,len
                shr     rcx,3
                rep movsq
                mov     rcx,len
                and     rcx,7
                rep movsb
        }    
Post 03 Oct 2022, 14:00
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 18942
Location: In your JS exploiting you and your system
revolution 03 Oct 2022, 14:14
Overclick wrote:
You cannot be sure registers still keeping your data after winapi.
The Windows API calling standard (stdcall for 32-bit) is well documented.

EBX, EDI, ESI & EBP are all guaranteed to be preserved upon return.
Post 03 Oct 2022, 14:14
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GREYSERGING



Joined: 03 Oct 2022
Posts: 4
GREYSERGING 03 Oct 2022, 16:58
Thanks
Post 03 Oct 2022, 16:58
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