Question

我是逆向工程的新手，我想了解更多，我试图反汇编一个目标exe，我遇到了一些我无法解释的函数。希望有人帮忙可以伸出援助之手。

00161000  /$ 83EC 08        SUB ESP,8
00161003  |. 6A 00          PUSH 0                                   ; /pHandle = NULL
00161005  |. 68 A8311600    PUSH Launcher.001631A8                   ; |FileName = 
0016100A  |. E8 81160000    CALL <JMP.&VERSION.GetFileVersionInfoSiz>; \GetFileVersionInfoSizeW
0016100F  |. 890424         MOV DWORD PTR SS:[ESP],EAX
00161012  |. 85C0           TEST EAX,EAX
00161014  |. 0F84 97000000  JE Launcher.001610B1
0016101A  |. 56             PUSH ESI
0016101B  |. 57             PUSH EDI
0016101C  |. 8B3D 8C301600  MOV EDI,DWORD PTR DS:[<&KERNEL32.GetProc>;  kernel32.GetProcessHeap
00161022  |. 50             PUSH EAX                                 ; /HeapSize
00161023  |. 6A 08          PUSH 8                                   ; |Flags = HEAP_ZERO_MEMORY
00161025  |. FFD7           CALL EDI                                 ; |[GetProcessHeap
00161027  |. 50             PUSH EAX                                 ; |hHeap
00161028  |. FF15 98301600  CALL DWORD PTR DS:[<&KERNEL32.HeapAlloc>>; \HeapAlloc
0016102E  |. 8BF0           MOV ESI,EAX
00161030  |. 8B4424 08      MOV EAX,DWORD PTR SS:[ESP+8]
00161034  |. 56             PUSH ESI                                 ; /Buffer
00161035  |. 50             PUSH EAX                                 ; |BufSize
00161036  |. 6A 00          PUSH 0                                   ; |Reserved = 0
00161038  |. 68 A8311600    PUSH Launcher.001631A8                   ; |FileName = 
0016103D  |. E8 42160000    CALL <JMP.&VERSION.GetFileVersionInfoW>  ; \GetFileVersionInfoW
00161042  |. 8D4C24 08      LEA ECX,DWORD PTR SS:[ESP+8]
00161046  |. 51             PUSH ECX                                 ; /pValueSize
00161047  |. 8D5424 10      LEA EDX,DWORD PTR SS:[ESP+10]            ; |
0016104B  |. 52             PUSH EDX                                 ; |ppValue
0016104C  |. 68 D0311600    PUSH Launcher.001631D0                   ; |pSubBlock = "\"
00161051  |. 56             PUSH ESI                                 ; |pBlock
00161052  |. E8 33160000    CALL <JMP.&VERSION.VerQueryValueW>       ; \VerQueryValueW
00161057  |. 8B4C24 0C      MOV ECX,DWORD PTR SS:[ESP+C]
0016105B  |. 8B41 08        MOV EAX,DWORD PTR DS:[ECX+8]
0016105E  |. 25 0000FFFF    AND EAX,FFFF0000
00161063  |. C1E0 0C        SHL EAX,0C
00161066  |. 894424 08      MOV DWORD PTR SS:[ESP+8],EAX
0016106A  |. 8B51 08        MOV EDX,DWORD PTR DS:[ECX+8]
0016106D  |. 83E2 0F        AND EDX,0F
00161070  |. C1E2 18        SHL EDX,18
00161073  |. 0BC2           OR EAX,EDX
00161075  |. 894424 08      MOV DWORD PTR SS:[ESP+8],EAX
00161079  |. 8B51 0C        MOV EDX,DWORD PTR DS:[ECX+C]
0016107C  |. 81E2 00007F00  AND EDX,7F0000*
00161082  |. 03D2           ADD EDX,EDX
00161084  |. 0BC2           OR EAX,EDX
00161086  |. 894424 08      MOV DWORD PTR SS:[ESP+8],EAX
0016108A  |. 8B49 0C        MOV ECX,DWORD PTR DS:[ECX+C]
0016108D  |. 81E1 FF1F0000  AND ECX,1FFF
00161093  |. 81C9 00A00100  OR ECX,1A000
00161099  |. 56             PUSH ESI                                 ; /pMemory
0016109A  |. 0BC1           OR EAX,ECX                               ; |
0016109C  |. 6A 00          PUSH 0                                   ; |Flags = 0
0016109E  |. 894424 10      MOV DWORD PTR SS:[ESP+10],EAX            ; |
001610A2  |. FFD7           CALL EDI                                 ; |[GetProcessHeap
001610A4  |. 50             PUSH EAX                                 ; |hHeap
001610A5  |. FF15 90301600  CALL DWORD PTR DS:[<&KERNEL32.HeapFree>] ; \HeapFree
001610AB  |. 8B4424 08      MOV EAX,DWORD PTR SS:[ESP+8]
001610AF  |. 5F             POP EDI
001610B0  |. 5E             POP ESI
001610B1  |> 83C4 08        ADD ESP,8
001610B4  \. C3             RETN

从地址 00161057 到 00161093 的部分是我真的不明白的事情。其余的只是调用不同的API，所以没有它。（文件名被删除）

如果有人能向我解释这个粗体部分，我真的很感激。

Answer 1

我的分析看起来像这样。

 
00161057  |. 8B4C24 0C      MOV ECX,DWORD PTR SS:[ESP+C] ; ppValue = struct VS_FIXEDFILEINFO*
0016105B  |. 8B41 08        MOV EAX,DWORD PTR DS:[ECX+8] ; ppValue+8 = dwFileVersionMS
0016105E  |. 25 0000FFFF    AND EAX,FFFF0000             ; 
00161063  |. C1E0 0C        SHL EAX,0C                   ; (dwFileVersionMS & 0xFFFF0000)  << 0xC
00161066  |. 894424 08      MOV DWORD PTR SS:[ESP+8],EAX ; save that value on stack
0016106A  |. 8B51 08        MOV EDX,DWORD PTR DS:[ECX+8] ; ppValue+8 = dwFileVersionMS
0016106D  |. 83E2 0F        AND EDX,0F       
00161070  |. C1E2 18        SHL EDX,18                   ; (dwFileVersionMS & 0xF) <<  0x18
00161073  |. 0BC2           OR EAX,EDX                   ; combine with previous value
00161075  |. 894424 08      MOV DWORD PTR SS:[ESP+8],EAX ; save that value on stack
00161079  |. 8B51 0C        MOV EDX,DWORD PTR DS:[ECX+C] ; ppValue+0xC = dwFileVersionLS
0016107C  |. 81E2 00007F00  AND EDX,7F0000*
00161082  |. 03D2           ADD EDX,EDX                  ; 2*(dwFileVersionLS & 0x7F0000)
00161084  |. 0BC2           OR EAX,EDX                   ; combine  with previous value
00161086  |. 894424 08      MOV DWORD PTR SS:[ESP+8],EAX ; save that value on the stack
0016108A  |. 8B49 0C        MOV ECX,DWORD PTR DS:[ECX+C] ; dwFileVersionLS
0016108D  |. 81E1 FF1F0000  AND ECX,1FFF
00161093  |. 81C9 00A00100  OR ECX,1A000                 ; dwFileVersionLS & 0x1FFFF | 0x1A000
00161099  |. 56             PUSH ESI                                 ; /pMemory
0016109A  |. 0BC1           OR EAX,ECX                               ; | combine with previous value
0016109C  |. 6A 00          PUSH 0                                   ; |Flags = 0
0016109E  |. 894424 10      MOV DWORD PTR SS:[ESP+10],EAX            ; | save value on the stack
001610A2  |. FFD7           CALL EDI                                 ; |[GetProcessHeap
001610A4  |. 50             PUSH EAX                                 ; |hHeap
001610A5  |. FF15 90301600  CALL DWORD PTR DS:[] ; \HeapFree
001610AB  |. 8B4424 08      MOV EAX,DWORD PTR SS:[ESP+8]             ; retrieve calculated value for return
001610AF  |. 5F             POP EDI
001610B0  |. 5E             POP ESI
001610B1  |> 83C4 08        ADD ESP,8
001610B4  \. C3             RETN

在C中看起来像：


DWORD ret = ((dwFileVersionMS & 0xFFFF0000) << 0xC) |
            ((dwFileVersionMS & 0xF) << 0x18) |
            (2*(dwFileVersionLS & 0x7F0000)) |
            (dwFileVersionLS & 0x1FFF) | 0x1A000;

Answer 2

我认为地址00161057上的指令是一个带有3个参数的函数，当ESP用作参数时，它通常是4个字节（DWORD）。现在，十进制的C是12.现在，内容ESP + C（c作为偏移量）引用第三个参数并存储在ECX中，然后将ECX + 8的内容复制到EAX并认为EAX + 8是一个全局变量。无论如何，如果我犯了错误，我的意见仍然会得到其他人的改善。

但是，您可以阅读wikibook的 x86反汇编 MOV EAX，DWORD PTR DS的寻址模式：[ECX + 8]指令

逆向工程师大会

2 个答案: