deepfuture

WIN32汇编-反汇编

学好WIN32汇编,平时需要多阅读编译器生成的汇编代码，因为编译器生成的代码是最规范和最优化的，从中可以学到汇编编程和语句优化的技巧。

如何得到一个程序的反汇编代码呢？使用反汇编软件，不是使用DOS的DEBUG，WINIODWS平台上已经有多反汇编软件，读者可以从下面的地址中下载反汇编软件

http://www.pediy.com/tools/Disassemblers/W32Dasm/W32dsm8.93.rar

下载示例分析文件GetID硬件特征码程序： http://www.91now.com/down/soft/137021.htm

http://www.91now.com/down/downpage.asp?id=137021&dp=1&fid=12

下面列出了取得硬件特征码程序的反汇编源代码，笔者将在随后对它进行分析：

Disassembly of File: D:\My Documents\GetID.exe
Code Offset = 00000400, Code Size = 00000200
Data Offset = 00000800, Data Size = 00000600

Number of Objects = 0004 (dec), Imagebase = 00400000h

   Object01:.text    RVA:00001000 Offset: 00000400 Size: 00000200 Flags: 60000020
   Object02:.rdata   RVA: 00002000 Offset:00000600 Size: 00000200 Flags: 40000040
   Object03:.data    RVA:00003000 Offset: 00000800 Size: 00000600 Flags: C0000040
   Object04:.rsrc    RVA:00004000 Offset: 00000E00 Size: 00002A00 Flags: C0000040

+++++++++++++++++++ 菜单信息 ++++++++++++++++++

程序没有菜单选项

+++++++++++++++++ 对话框信息 ++++++++++++++++++

There Are No Dialog Resources in This Application

+++++++++++++++++++ 导入函数 ++++++++++++++++++
Number of Imported Modules= 2(decimal)

Import Module 001:user32.dll
Import Module 002:kernel32.dll

+++++++++++++++++++ 重要模块资料 +++++++++++++++

Import Module 001:user32.dll

Addr:0000206C hint(019D) Name:MessageBoxA

Import Module 002:kernel32.dll

Addr:000020A6 hint(0080) Name:ExitProcess
Addr:00002086 hint(0030) Name: CreateFileA
Addr:00002094 hint(005A) Name:DeviceIoControl

+++++++++++++++++++ 导出函数 ++++++++++++++++++
Number of Exported Functions = 0000 (decimal)

+++++++++++++++++++ ASSEMBLY CODE LISTING ++++++++++++++++++
//********************** Start of Code in Object .text**************
Program Entry Point = 00401000 (D:\My Documents\GetID.exe FileOffset:00001600)

//******************** Program Entry Point ********
:00401000B801000000             mov eax, 00000001
:004010050FA2                   cpuid
:00401007BEB7304000             mov esi, 004030B7
:0040100C50                     push eax
:0040100DE8E7000000             call 004010F9
:004010128906                   mov dword ptr [esi], eax
:0040101453                     push ebx
:00401015E8DF000000             call 004010F9
:0040101A894604                 mov dword ptr [esi+04], eax
:0040101D51                     push ecx
:0040101EE8D6000000             call 004010F9
:00401023894608                 mov dword ptr [esi+08], eax
:0040102652                     push edx
:00401027E8CD000000             call 004010F9
:0040102C89460C                 mov dword ptr [esi+0C], eax
:0040102FBF54304000             mov edi, 00403054
:00401034B910000000             mov ecx, 00000010
:00401039AC                     lodsb
:0040103AE8D9000000             call 00401118
:0040103F66AB                   stosw
:00401041E2F6                   loop 00401039
:004010436A00                   push 00000000
:004010456A00                   push 00000000
:004010476A03                   push 00000003
:004010496A00                   push 00000000
:0040104B6A03                   push 00000003
:0040104D68000000C0             push C0000000

* Possible StringData Ref from Data Obj->" \\.\PhysicalDrive0"
|
:0040105268A0304000 push 004030A0

* Reference To: kernel32.CreateFileA, Ord:0030h
                                 |
:00401057E8DE000000             Call 0040113A
:0040105CA3B3304000             mov dword ptr [004030B3], eax
:00401061BBC7304000             mov ebx, 004030C7
:00401066C70300020000           mov dword ptr [ebx], 00000200
:0040106CC7430400010100         mov [ebx+04], 00010100
:00401073C7430800A0EC00         mov [ebx+08], 00ECA000
:0040107AC7430C00000000         mov [ebx+0C], 00000000
:00401081BBF7334000             mov ebx, 004033F7
:00401086C70312000000           mov dword ptr [ebx], 00000012
:0040108CC74304EC000000         mov [ebx+04], 000000EC
:00401093C7430801010001         mov [ebx+08], 01000101
:0040109AC7430C07000000         mov [ebx+0C], 00000007
:004010A16A00                   push 00000000
:004010A368F7334000             push 004033F7
:004010A86813020000             push 00000213
:004010AD68F7304000             push 004030F7
:004010B26A23                   push 00000023
:004010B468C7304000             push 004030C7
:004010B96888C00700             push 0007C088
:004010BEFF35B3304000           push dword ptr [004030B3]

* Reference To: kernel32.DeviceIoControl, Ord:005Ah
                                 |
:004010C4E877000000             Call 00401140
:004010C9BE1B314000             mov esi, 0040311B
:004010CEBF28304000             mov edi, 00403028
:004010D3B90A000000             mov ecx, 0000000A
:004010D866AD                   lodsw
:004010DA86C4                   xchg ah, al
:004010DC66AB                   stosw
:004010DEE2F8                   loop 004010D8
:004010E06A00                   push 00000000

* Possible StringData Ref from Data Obj->"本机硬件ID："
|
:004010E26800304000 push 00403000

* Possible StringData Ref from Data Obj->"你的硬件ID是：

硬盘ID： "
->"

"
->"CpuID： "
->"

小技巧：你可以按 "
                                       ->"Ctrl+C 复制本框内容!"
                                 |
:004010E7680E304000             push 0040300E
:004010EC6A00                   push 00000000

* Reference To: user32.MessageBoxA, Ord:019Dh
                                 |
:004010EEE841000000             Call 00401134
:004010F350                     push eax

* Reference To: kernel32.ExitProcess, Ord:0080h
|
:004010F4E84D000000 Call 00401146

* Referenced by a CALL at Addresses:
|:0040100D   ,:00401015   ,:0040101E   ,:00401027
|
:004010F955                     push ebp
:004010FA8BEC                   mov ebp, esp
:004010FC53                     push ebx
:004010FD51                     push ecx
:004010FE8B4508                 mov eax, dword ptr [ebp+08]
:00401101B903000000             mov ecx, 00000003
:004011068AD8                   mov bl, al
:00401108C1E808                 shr eax, 08
:0040110BC1E308                 shl ebx, 08
:0040110EE2F6                   loop 00401106
:004011108BC3                   mov eax, ebx
:0040111259                     pop ecx
:004011135B                     pop ebx
:00401114C9                     leave
:00401115C20400                 ret 0004

* Referenced by a CALL at Address:
|:0040103A
|
:004011188AE0                   mov ah, al
:0040111AC0E804                 shr al, 04
:0040111D80E40F                 and ah, 0F
:0040112080FC0A                 cmp ah, 0A
:004011237203                   jb 00401128
:0040112580C407                 add ah, 07

* Referenced by a (U)nconditional or (C)onditional Jump atAddress:
|:00401123(C)
|
:004011283C0A                   cmp al, 0A
:0040112A7202                   jb 0040112E
:0040112C0407                   add al, 07

* Referenced by a (U)nconditional or (C)onditional Jump atAddress:
|:0040112A(C)
|
:0040112E66053030 add ax, 3030
:00401132C3 ret

:00401133CC int 03

* Referenced by a CALL at Address:
|:004010EE
|

* Reference To: user32.MessageBoxA, Ord:019Dh
|
:00401134FF2510204000 Jmp dword ptr [00402010]

* Referenced by a CALL at Address:
|:00401057
|

* Reference To: kernel32.CreateFileA, Ord:0030h
|
:0040113AFF2504204000 Jmp dword ptr [00402004]

* Referenced by a CALL at Address:
|:004010C4
|

* Reference To: kernel32.DeviceIoControl, Ord:005Ah
|
:00401140FF2508204000 Jmp dword ptr [00402008]

* Reference To: kernel32.ExitProcess, Ord:0080h
                                 |
:00401146FF2500204000           Jmp dword ptr [00402000]
:0040114C00000000000000000000   BYTE 10 DUP(0)
:0040115600000000000000000000   BYTE 10 DUP(0)
:0040116000000000000000000000   BYTE 10 DUP(0)
:0040116A00000000000000000000   BYTE 10 DUP(0)
:0040117400000000000000000000   BYTE 10 DUP(0)
:0040117E00000000000000000000   BYTE 10 DUP(0)
:0040118800000000000000000000   BYTE 10 DUP(0)
:0040119200000000000000000000   BYTE 10 DUP(0)
:0040119C00000000000000000000   BYTE 10 DUP(0)
:004011A600000000000000000000   BYTE 10 DUP(0)
:004011B000000000000000000000   BYTE 10 DUP(0)
:004011BA00000000000000000000   BYTE 10 DUP(0)
:004011C400000000000000000000   BYTE 10 DUP(0)
:004011CE00000000000000000000   BYTE 10 DUP(0)
:004011D800000000000000000000   BYTE 10 DUP(0)
:004011E200000000000000000000   BYTE 10 DUP(0)
:004011EC00000000000000000000   BYTE 10 DUP(0)
:004011F600000000000000000000   BYTE 10 DUP(0)

有经验的程序员都知道,看别人代码是写代码必练的基本功，下面笔者和大家一起来看懂这段看似天书的汇编代码。

这是一段子程序，:0040100D ,:00401015 ,:0040101E ,:00401027 都对它进行了调用。所以先对这个子程序进行研究

:004010FE8B4508                 mov eax, dword ptr [ebp+08]
:00401101B903000000             mov ecx, 00000003
:004011068AD8                   mov bl, al
:00401108C1E808                 shr eax, 08
:0040110BC1E308                 shl ebx, 08
:0040110EE2F6                   loop 00401106
:004011108BC3                   mov eax, ebx

可以这个是一个循环，一循环三次

目的是将eax的值以字节为单位，反过来存放,存储器以字节为单位进行存储，对于字(16位)，将要低8位放在低位地址，将高8位放在高位地址，因为存储器的地址单元是增加方向增长的，所以先将低8位放在ah,再将高8位取出放在AL，所以要反序取出。

ret指令返回并将调用者存放在堆栈中的返回地址弹出到EIP中，如果是段间调用的返回，弹出到CS：EIP

call执行的功能（段间），按顺序如下：

1、将CS寄存器中的值压入堆栈

2、把CALL指令的下条指令的32位偏移地址压入堆栈

3、拷贝48位的有效地址到CS：EIP

4、程序从了程序的第一条指令处开始执行

二、ret 立即数

这种方式是指把返回地址弹出堆栈后，把该值与esp加，相当于堆栈顶去掉了若干字节的内容

因为al中放了参数，所以将EAX的AL中的高4位移到ah中，要达到以十六进制显示，并且ASCII码为8位，所以进行了扩展，并且将十六进制码转化为ASCII码，

* Referenced by a (U)nconditional or (C)onditional Jump atAddress:
|:0040112A(C)
|
:0040112E66053030 add ax, 3030
:00401132C3 ret

以上完成将al由数字或字符分别转化成相应的两个ASCII码。

存储器以字节为单位进行存储，对于字(16位)，将要低8位放在低位地址，将高8位放在高位地址，因为存储器的地址单元是增加方向增长的，且字的存储地址是低地址，取CPU序列号时，以4位为单位，所以先将低4位AL的低4位中，再将高4取出放在AL的高4位中，因此，这个子程序将AL的高位和低位调换过来，以还原正常。

//******************** Program Entry Point ********
:00401000B801000000 mov eax, 00000001
:004010050FA2 cpuid

取得cpuid，从低32位到高32位放在eax,ebx,ecx,edx,

:00401007BEB7304000             mov esi, 004030B7
:0040100C50                     push eax
:0040100DE8E7000000             call 004010F9
:004010128906                   mov dword ptr [esi], eax
:0040101453                     push ebx
:00401015E8DF000000             call 004010F9
:0040101A894604                 mov dword ptr [esi+04], eax
:0040101D51                     push ecx
:0040101EE8D6000000             call 004010F9
:00401023894608                 mov dword ptr [esi+08], eax
:0040102652                     push edx
:00401027E8CD000000             call 004010F9
:0040102C89460C                 mov dword ptr [esi+0C], eax

调用子程序对CPUID进行反序，以还原正常的数值，因为存储将高位放在高地址，低位放在低地址。
:0040102FBF54304000             mov edi, 00403054
:00401034B910000000             mov ecx, 00000010
:00401039AC                     lodsb
:0040103AE8D9000000             call 00401118
:0040103F66AB                   stosw
:00401041E2F6                   loop 00401039

用4位单位进一步反序CPUID，并转化为ASCII码。
:004010436A00                   push 00000000
:004010456A00                   push 00000000
:004010476A03                   push 00000003
:004010496A00                   push 00000000
:0040104B6A03                   push 00000003
:0040104D68000000C0             push C0000000

* Possible StringData Ref from Data Obj->" \\.\PhysicalDrive0"
|
:0040105268A0304000 push 004030A0

放置调用API的参数，最后入堆栈的参数是第一个参数

* Reference To: kernel32.CreateFileA, Ord:0030h
                                 |
:00401057E8DE000000             Call 0040113A
0040105CA3B3304000             mov dword ptr [004030B3], eax
:00401061BBC7304000             mov ebx, 004030C7

以下是二个变量的赋值
:00401066C70300020000           mov dword ptr [ebx], 00000200
:0040106CC7430400010100         mov [ebx+04], 00010100
:00401073C7430800A0EC00         mov [ebx+08], 00ECA000
:0040107AC7430C00000000         mov [ebx+0C], 00000000
:00401081BBF7334000             mov ebx, 004033F7
:00401086C70312000000           mov dword ptr [ebx], 00000012
:0040108CC74304EC000000         mov [ebx+04], 000000EC
:00401093C7430801010001         mov [ebx+08], 01000101
:0040109AC7430C07000000         mov [ebx+0C], 00000007

以下放置参数，调用API，取硬盘ID
:004010A16A00                   push 00000000
:004010A368F7334000             push 004033F7
:004010A86813020000             push 00000213
:004010AD68F7304000             push 004030F7
:004010B26A23                   push 00000023
:004010B468C7304000             push 004030C7
:004010B96888C00700             push 0007C088
:004010BEFF35B3304000           push dword ptr [004030B3]

* Reference To: kernel32.DeviceIoControl, Ord:005Ah
|
:004010C4E877000000 Call 00401140

以下将取出的硬盘ID反序，以还原正常

:004010C9BE1B314000             mov esi, 0040311B
:004010CEBF28304000             mov edi, 00403028
:004010D3B90A000000             mov ecx, 0000000A
:004010D866AD                   lodsw
:004010DA86C4                   xchg ah, al
:004010DC66AB                   stosw
:004010DEE2F8                   loop 004010D8

:004010E06A00 push 00000000