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DSblizzard



Joined: 23 Oct 2019
Posts: 15
Location: Ryazan, Russia
DSblizzard
I tried all of commented and uncommented code, but nothing works.
Code:
format PE64 console
entry prog

include "win64ax.inc"

section '.idata' import data readable writeable

library kernel32, 'kernel32.dll', msvcrt, 'msvcrt.dll'

import kernel32, ExitProcess,'ExitProcess'
import msvcrt, memmove, 'memmove'

section '.text' code readable executable

prog:

;;mov rdx, 4
;;push rdx
;;mov rsi, temp_str
;;push rsi
;;mov rdi, temp_str1
;;push rdi
;;call memmove


;;sub   rsp, 24
;;mov   [rsp + 16], rdx
;;mov   [rsp + 8], rsi
;;mov   [rsp], rdi
;;call memmove
;;add rsp, 24


;;push rbp
;;mov rbp, rsp
;;push rdx
;;push rsi
;;push rdi
;;call memmove
;;mov rsp, rbp
;;pop rbp


sub rsp, 32
mov rcx, temp_str1
mov rdx, temp_str
mov r8, 3
call memmove
add rsp, 32

end_prog:
        invoke ExitProcess, 0

section '.data' data readable writeable
        temp_str db "abc", 0
        temp_str1 db "def", 0
    

Don't suggest cinvoke because it seems to have a bug. Some combinations of registers work, others don't.
Post 18 Nov 2019, 14:10
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 16904
Location: In your JS exploiting you and your system
revolution
memmove is a pointer so you need to dereference it:
Code:
call [memmove]    
Post 18 Nov 2019, 16:51
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DSblizzard



Joined: 23 Oct 2019
Posts: 15
Location: Ryazan, Russia
DSblizzard
Thank you, now it works. But following code still crashes:
mov rdi, temp_str1
mov rsi, temp_str
mov rdx, 3
cinvoke memmove, rdi, rsi, rdx
Is cinvoke supposed to work only with certain registers? Seems like it is a bug.
Post 18 Nov 2019, 17:15
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 16904
Location: In your JS exploiting you and your system
revolution
You need to be aware of the register allocation order that cinvoke uses. When you have an overlap like you do in your example then currently the only way to solve it is to manually set the registers.
Post 18 Nov 2019, 17:22
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