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[原创]Themida IAT处理部分的简单分析
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发表于: 2008-9-22 13:40 7100
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Themida IAT处理部分的简单分析
下面类似的代码大家可以随便找个themida 1.9.x加密的文件,然后运行fxyang 的脚本,运行到370行左右
就到了下面代码的 范围
(本文所列代码已经去除变形代码,有些代码使用等效代码代替)
有不足之处,请大家批评指正
D331F95: pDllBase
D333185: NumberOfNames
D3316A9: EndOfFuncAddr
D330EB5: Base(输出表)
D333671; AddressOfFunctions
D3337E1: AddressOfNames
D331739: AddressOfNameOrdinals
038F6B60 mov ebx, dword ptr [ebp+D331F95]
038F6B83 mov ecx, dword ptr [ebx]
038F6BB8 cmp ecx, 0
038F6BBB je 038FAA6B
038F6BD1 push eax
038F6BFE push ecx
038F6C15 pushad
038F6C17 xor eax, eax
038F6C1A mov dword ptr [ebp+D333725], eax
038F6C44 mov esi, 3C ;熟悉的常数
038F6C61 add esi, dword ptr [esp+20]
038F6C84 lods word ptr [esi]
038F6CAC add eax, dword ptr [esp+20]
038F6CB6 push dword ptr [eax+78] ;典型的寻找输出表
038F6CAB pop esi
038F6CD9 add esi, dword ptr [esp+20]
038F6CEA push dword ptr [esi+18] ;NumberOfNames?
038F6CED pop edi
038F6CF5 mov dword ptr [ebp+D333185], edi
038F6CFC test edi, edi
038F6CFE jnz 038F6D36
038F6D36 push ecx
038F6D4F mov edx, edi
038F6D67 imul edx, edx, 4
038F6D7A mov dword ptr [ebp+D3316A9], edx
038F6D8F push 4
038F6D98 push 1000
038F6DA7 push edx
038F6DCD push 0
038F6DD9 call dword ptr [ebp+D33319D] ;VirutalAlloc?
038F6DE6 mov dword ptr [ebp+D332CE9], eax ;保存分配的空间地址
038F6E0C mov edx, eax
038F6E1C pop ecx
<< call 038FD38A >>
038FD38A push eax
038FD3AB mov eax, dword ptr [esi+10] ; Base
038FD3B6 mov dword ptr [ebp+D330EB5], eax
038FD3E3 pop eax
038FD3F8 mov ebx, dword ptr [esi+1c] ; AddressOfFunctions
038FD402 lea edi, dword ptr [ebp+D333671]
038FD421 lods dword ptr [esi] << AddressOfFunctions
038FD441 add eax, dword ptr [esp+24]
038FD463 stos dword ptr es:[edi]
038FD471 lea edi, dword ptr [ebp+D3337E1]
038FD478 lods dword ptr [esi] << AddressOfNames
038FD4AA add eax, dword ptr [esp+24]
038FD4B8 push eax
038FD4CF stos dword ptr es:[edi]
038FD4E9 lea edi, dword ptr [ebp+D331739]
038FD50C lods dword ptr [esi] << AddressOfNameOrdinals
038FD53B add eax, dword ptr [esp+28]
038FD55B stos dword ptr es:[edi]
038FD586 pop esi
038F6E5A push esi
038F6E7B lods dword ptr [esi] 提取函数名
038F6E87 add eax, dword ptr [esp+24]
038F6E96 xor eax, edi
038F6E98 xor edi, eax
038F6E9A xor eax, edi
038F6EA0 mov ebx, edi
038F6EA4 push edi
038F6EC9 xor al, al
038F6ECC rep scas byte ptr es:[edi] 寻找字符串结尾
038F6EE1 pop esi
038F6EFA sub edi, ebx
038F6F18 push edx
038F6F3C mov edx, edi ;函数名长度
038F6F54 mov edi, dword ptr [ebp+D331799]
038F6F5B mov ecx, -1
038F6F78 xor eax, eax 开始处理函数名(crc32?)
038F6F9B mov al, byte ptr [esi]
038F6F9F xor al, cl
038F6FAE inc esi
038F6FC0 mov eax, dword ptr [edi+eax*4]
038F6FCB shr ecx, 8
038F6FCF xor ecx, eax
038F6FEC dec edx
038F6FED jnz 038F6F78
038F702B mov eax, ecx
038F703B not eax
038F7050 pop edx
038F7070 mov dword ptr [edx],eax
038F7098 add edx, 4
038F70C6 push edx
038F70CF inc dword ptr [ebp+D333725]
038F70F0 mov edx, dword ptr [ebp+D333725]
038F7102 cmp dword ptr [ebp+D333185], edx
038F7108 je 038F7185
038F7112 pop edx
038F713E pop esi
038F715D add esi, 4
038F7167 jmp 038F6E5A
038F7197 pop edx
038F71AB pop esi
038F71C1 popad
038F71D5 pop ecx
038F71EF pop eax
038F7202 mov dword ptr [ebp+D332401], 0
038F720C mov dword ptr [ebp+D332D29], 0
038F7216 cmp dword ptr [ebp+D3E344A], 0
038F721D je short 038F7227
038F721F lea ebx, dword ptr [ebp+D3C15FF]
038F7225 call ebx
038F7227 inc dword ptr [ebp+SelfCheckFlag]
038F7248 cmp dword ptr [ebp+SelfCheckFlag], 64
038F724F jb 038F7348 ;貌似自校验,100次循环检查一下
;这里跳转就是不检查
038F734A mov ecx, 020A27F1
038F7371 mov edx, 777F107C
038F738A lods dword ptr [esi] ;又是处理加密表
038F73A9 mov dword ptr [ebp+EnCryIAT], esi
038F73C4 mov dword ptr [esi-4], 0
038F73CD cmp eax, EEEEEEEE
038F73D2 jnz 038F749A ;E后面连接D ,下一个输入文件
038F73E9 cmp dword ptr [esi], DDDDDDDD
038F73EF jnz 038F749A
038F7413 mov dword ptr [esi], 0 ;如果是dddddddd 则清零,跳转
038F7446 add esi, 4
038F745A mov dword ptr [ebp+EnCryIAT], esi
038F748E jmp 038FA981
038F749B mov ebx, eax
038F74B3 xor eax, dword ptr [ebp+D330881] ;与前一个组数据头异或
038F74D2 ror eax, 3
038F74E9 sub eax, edx ;上面给的固定值777F107C
038F7509 rol eax, 10
038F7523 xor eax, ecx ;
038F7526 mov dword ptr [ebp+D330881], ebx
038F752D cmp eax, 10000 ; 计算结果是否小于10000
038F7532 jnb 038F77DE
038F754F cmp dword ptr [esi], BBBBBBBB ;下一个数据是否是B
038F7555 jnz 038F77DE
038F7577 mov dword ptr [esi], 0
038F75B2 add esi, 4
038F75EF mov dword ptr [ebp+ EnCryIAT], esi
038F7602 mov ebx, dword ptr [ebp+D331F95]
038F7621 mov ecx, dword ptr [ebx]
038F7646 mov edx, eax
038F7660 pushad
038F766F mov eax, edx
038F7680 sub eax, dword ptr [ebp+D330EB5]
038F7687 shl eax, 2
038F769C add eax, dword ptr [ebp+D333671]
038F76A3 xchg eax,esi
038F76B8 lods dword ptr [esi]
038F76CF add eax, ecx
038F76EA mov dword ptr [esp+1C], eax
038F76FB mov byte ptr [ebp+D3E3526], 0
038F770E mov dword ptr [ebp+D3E352F], 0
038F7719 mov edi, dword ptr [ebp+D331F95]
038F7728 mov edi, dword ptr [edi]
038F7753 cmp edi, dword ptr [ebp+D3308AD]
038F7759 je 038F77B6
038F7771 cmp edi, dword ptr [ebp+D333319]
038F7777 je 038F77B6
038F778F cmp edi, dword ptr [ebp+D333105]
038F7795 jnz 038F77C9
038F77B6 mov byte ptr [ebp+D3E3526], 1
038F77C9 popad
038F77D8 jmp 038F7D55
038F77DE push ecx
038F77ED push edx
038F7824 xor ecx, ecx
038F7834 mov edx, dword ptr [ebp+D332CE9] ; 加密的函数名 数组
038F783B cmp eax, dword ptr [edx] ;循环找到和eax相同的数值
038F783D je 038F78EA
038F785E add edx, 4
038F785E inc ecx ;记录序号
038F787E cmp ecx, dword ptr [ebp+D333185]
038F7884 jnz 038F783B
038F78EA mov dword ptr [ebp+D33725], ecx ;保存序号
038F78FE mov byte ptr [ebp+Flag526], 0 ;flag置0
038F7905 mov dword ptr [ebp+Flag52F], 0 ;flag置0
038F7918 mov ecx, dword ptr [ebp+D331F95] ;这里储存的是指针
038F791E mov ecx, dword ptr [ecx] ;dll文件基地址
038F7920 cmp ecx, dword ptr [ebp+D3308AD] 比较是否是 user32.dll
038F7926 je short 038F7938
038F7928 cmp ecx, dword ptr [ebp+D333319] 比较是否是 advapi32.dll
038F792E je short 038F7938
038F7930 cmp ecx, dword ptr [ebp+kernel32Base] 比较是否是 Kernel32.dll
038F7936 jnz short 038F7964
038F7938 mov byte ptr [ebp+Flag526], 1 ;进入特殊dll标志
038F793F lea edx, dword ptr [ebp+D3E3533] ;4个特殊函数?
038F7945 lea ecx, dword ptr [ebp+D3E3543]
038F794B jmp short 038F7960
038F794D cmp dword ptr [edx], eax
038F794F jnz short 038F795D
038F7951 mov dword ptr [ebp+Flag52F], 1 ;4个特殊函数标志
038F795B jmp short 038F7964
038F795D add edx, 4
038F7960 cmp edx, ecx
038F7962 jb short 038F794D
038F7979 pop edx
038F797E pop ecx
038F7986 push esi
038F79AA mov ebx, dword ptr [ebp+D331F95] ;pCurDllBase
038F79D2 mov ecx, dword ptr [ebx] ;dll文件基地址
038F79E7 mov eax, dword ptr [ebp+D33725] ;上面找到的序号
038F79FE shl eax, 1
038F7A01 add eax, dword ptr [ebp+D331739] ; AddressOfOrdinals
038F7A08 xor esi, esi
038F7A19 xchg eax,esi
038F7A2C lods word ptr [esi]
038F7A49 shl eax, 2
038F7A4D add eax, dword ptr [ebp+D333671] ; AddressOfFunctions
038F7A5B xchg eax,esi
038F7A73 lods dword ptr [esi]
038F7A8F add eax, ecx ;前面是Themida自己的GetProcAddressByKey
038F7ADC cmp dword ptr [eax], 0E8 ;检查api函数第一个字节(dword比较?)
038F7AE2 jnz 038F7C7E
038F7C8A cmp dword ptr [eax], 6C687069 ;iphlpapi 奇怪的检查,看不懂
038F7C90 jnz 038F7D20
038F7CA0 cmp dword ptr [eax+4], 69706170
038F7CA7 jnz 038F7D20
038F7D23 pop esi
038F7D55 mov ebx, dword ptr [ebp+D330E11] ;标志位E11
038F7D80 dec ebx
038F7D81 je 038F7EA3 ;检查ebx是否为1
038F7D8D mov ebx, dword ptr [ebp+kernel32Base] ; kernel32.7C800000
038F7DA7 sub ebx, ecx 比较是否是 Kernel32.dll
038F7DA9 je 038F7EA3 ;fxyang的脚本修改这里避开加密.新版已经无效
038F7DD7 mov ebx, dword ptr [ebp+ user32]
038F7DE7 clc
038F7DE8 sub ebx, ecx 比较是否是 user32.dll
038F7DEA je 038F7EA3 ;fxyang的脚本修改这里避开加密.新版已经无效
038F7E01 mov ebx, dword ptr [ebp+ advapi32] ; 3844475
038F7E14 sub ebx, ecx 比较是否是 advapi32.dll
038F7E16 je 038F7EA3 ;fxyang的脚本修改这里避开加密.新版已经无效
//正常dll处理过程
038F7E1C cld
038F7E1D lea ebx, dword ptr [ebp+D3E9915] ; 38faa71
038F7E39 call ebx ;038FAA71
038F7E48 mov edi, eax
038F7E55 cmc
038F7E56 mov dword ptr [ebp+CurAPIFunc], eax ;存储当前正在处理的函数地址
038F7E73 jmp 038FA189
;特殊dll处理过程
038F7EA3 lea ebx, dword ptr [ebp+D3E9915]
038F7EB3 call ebx ;038FAA71
038F7EC8 cmp dword ptr [ebp+D330E11], 0 ;这个标志估计和加密dll有关
038F7ECF je 038F7F38
038F7F38 cmp eax, dword ptr [ebp+D33001D] ; kernel32.ExitProcess
038F7F3E jnz 038F7FA0
038F7FA0 cmp eax, dword ptr [ebp+D33001D] ; kernel32.ExitProcess
038F7FA6 je 038F7E1D
038F7FC7 cmp dword ptr [ebp+D3E342E], 1
038F7FCE jnz 038F8035
038F8035 xor edi, edi
038F803E cmp dword ptr [ebp+D33364D], 0 ;貌似没有作用
038F8045 je 038F93EC
038F940C cmp eax, dword ptr [ebp+D3321C9] ; USER32.wsprintfA
038F9412 jnz 038F9469
038F9469 cmp eax, dword ptr [ebp+D3327BD] ; kernel32.RaiseException
038F946F jnz 038F9555
038F9555 cmp eax, dword ptr [ebp+D3E343E] ; ntdll.RtlEnterCriticalSection
038F955B je 038F95B2
038F9599 cmp eax, dword ptr [ebp+D3E3442] ; ntdll.RtlLeaveCriticalSection
038F959F jnz 038F95B8
038F95DF mov esi, eax
038F967A mov dword ptr [ebp+D33262D], esi ; kernel32.OutputDebugStringA
038F9681 mov dword ptr [ebp+D3309A1], esi
038F97ED mov edi, dword ptr [ebp+D3305A5]
038F9802 mov dword ptr [ebp+D332029], 0
038F983C mov dword ptr [ebp+D3309A1], esi ; kernel32.OutputDebugStringA
038F984C lea ebx, dword ptr [ebp+D3EBEE8]
038F9864 call ebx ;结束以后eax=0
038F9881 or eax, eax
038F9883 je 038F98B1
038F9890 jmp 038F9945 <<这里跳出 寻找到jmp指令
038F98B1 lea ebx, dword ptr [ebp+D3A365C]
038F98C9 call ebx ; esi移动到下一个指令
038F98CB jnb 038F983C
038F98D4 mov esi, dword ptr [ebp+D3309A1]
038F98E0 jmp 038F98F5
038F9945 mov eax, dword ptr [ebp+D33262D]
038F9952 mov dword ptr [ebp+D3309A1], eax ; kernel32.OutputDebugStringA
038F999A cmp byte ptr [esi], 0E8
038F999D jnz 038F9A85
038F99AE cmp dword ptr [ebp+D330E21], 0
038F99B5 je 038F9A85
038F99E3 mov al, ??
038F99FE stos byte ptr es:[edi]
038F9A06 mov eax, esi
038F9A11 sub eax, edi
038F9A32 sub eax, 4
038F9A4E stos dword ptr es:[edi]
038F9A63 jmp 038F9C9C
038F9A85 lea ebx, dword ptr [ebp+D3EA5A3]
038F9A9E call ebx ;038FB6FF
038F9AA1 lea ebx, dword ptr [ebp+D3EB8F9]
038F9AB6 call ebx ;038FCA55
038F9ABF or eax, eax
038F9AC1 jnz 038F9AD7
038F9AC8 jmp 038F9B05
038F9AD7 add dword ptr [ebp+D3309A1], 5
038F9AEE jmp 038F999A
038F9B05 lea ebx, dword ptr [ebp+D3EBAC5]
038F9B17 call ebx ;038FCC21
038F9B36 or eax, eax
038F9B38 jnz 038F9B6C
038F9B52 jmp 038F9B9C
038F9B78 add edx, ebx
038F9 B80 jmp 038F9C9C
038F9B9C lea ebx, dword ptr [ebp+D3A365C]
038F9BB9 call ebx ;038B47B8
038F9BE5 mov ecx, dword ptr [ebp+D3309A1] ; kernel32.OutputDebugStringA
038F9BFD mov dword ptr [ebp+D3309A1], esi ; kernel32.7C859D7D
038F9C1A sub ecx, esi
038F9C39 not ecx
038F9C3D inc ecx
038F9C5A sub esi, ecx
038F9C66 rep movs byte ptr es:[edi], byte ptr [esi] <,将api函数体复制到edi
038F9C6F jmp 038F999A
038F9C9C lea ebx, dword ptr [ebp+D3C15FF]
038F9CA3 call ebx ;
038F9CBF mov eax, edi ;复制代码的末尾
038F9CC9 sub eax, dword ptr [ebp+D3305A5] ;-代码头,得到长度
038F9CE5 mov dword ptr [ebp+D331689], eax ;保存长度
038F9CF9 mov eax, dword ptr [ebp+D3305A5]
038F9D00 push edi
038F9D00 push eax
038F9D39 lea ecx, dword ptr [ebp+D3C183C]
038F9D46 call ecx ;038D2998
05AD0059 add byte ptr [eax], al
038F9D5B push eax
038F9D72 push edi
038F9D7B mov eax, dword ptr [ebp+D3305A5]
038F9D9C push eax
038F9DB6 lea ecx, dword ptr [ebp+D3C1974]
038F9DD2 call ecx ;生成一份变态的代码,
038F9DD7 mov edx, eax ;代码结尾
038F9E0A mov ecx, eax ;四处乱放
038F9E11 sub ecx, dword ptr [ebp+D3326CD] 又要计算长度了
038F9E21 cmp dword ptr [ebp+D332A99], 0
038F9E28 je 038F9F0E
038F9F0E push ecx
038F9F44 mov eax,ecx
038F9F54 sub eax, 1
038F9F79 or eax, 0FFF ;计算长度是否超出页面?
038F9F8E inc eax
038F9F96 mov dword ptr [ebp+D332475], eax
038F9FB6 add dword ptr [ebp+D33373D], eax
038F9FC9 mov dword ptr [ebp+D332A99], 0
038F9FDA push 40
038F9FE9 push 1000
038F9FFC push ecx
038FA012 push 0
038FA01F call dword ptr [ebp+D33319D] ;VirutalAlloc?
038FA026 call dword ptr [ebp+D3303C1] ;03845981
038FA03E mov dword ptr [ebp+D3304A1], eax ;新分配的地址
038FA04B mov dword ptr [ebp+D332DD1], eax
038FA067 pop ecx
038FA07C push dword ptr [ebp+D332DD1] 新地址
038FA094 push dword ptr [ebp+D3326CD] 变态代码地址
038FA0A1 push edi api代码结束地址
038FA0CD push dword ptr [ebp+D3305A5] api代码开始地址
038FA0F7 lea eax, dword ptr [ebp+D3C3149]
038FA118 call eax ; 038D42A5打算干什么呢?
038FA11B add dword ptr [ebp+D332A99], ecx
038FA154 mov edi, dword ptr [ebp+D332DD1]
038FA15B mov esi, dword ptr [ebp+D3326CD]
038FA16B rep movs byte ptr es:[edi], byte ptr [esi] 移动代码到新的地址
038FA189 mov esi, dword ptr [ebp+EnCryIAT] ;加密表地址
038FA19D lods dword ptr [esi]
038FA1B7 mov dword ptr [esi-4], 0 ;清零
038FA1CE mov ecx, 2
038FA1E9 or ecx, ecx
038FA1EB jnz 038FA211
038FA200 mov dword ptr [ebp+Flag52F], 1
038FA20A ja 038FA211
038FA211 cmp byte ptr [ebp+Flag526], 0 ; 38f4682
038FA218 je 038FA2B2
038FA22A cmp dword ptr [ebp+Flag52F], 0
038FA231 jnz 038FA2B2
038FA255 call dword ptr [ebp+D3320C1] <<关键函数,这个函数就是处理加密api的iat的
函数很复杂,我是没精力看了,依靠各位了
038FA271 mov byte ptr [ebp+Flag526], 0
038FA284 jmp 038FA393
038FA2B2 rol eax, 5
038FA2CA add eax, 020A27F1 ;对加密表的数据进行处理
038FA2ED add eax, dword ptr [ebp+D3319B9] ;00400000
;加上基地址
038FA2F4 mov ecx, dword ptr [ebp+CurAPIFunc] ; IMM32.ImmCreateContext
;上面存储的函数地址
038FA301 mov dword ptr [eax], ecx ;填入iat
038FA307 lods dword ptr [esi] ;载入加密表的下一个数据
038FA315 mov dword ptr [esi-4],0 ;清零
038FA330 mov dword ptr [ebp+EnCryIAT], esi ; 存储下个处理的加密表地址
038FA35A cmp eax, -1 ;比较数据是否是FFFFFFFF
038FA35D jnz 038FA421
038FA379 cmp dword ptr [esi], DDDDDDDD
038FA37F jnz 038FA421
038FA3AA mov dword ptr [esi], 0 ; 如果FFFFFFFF后面是DDDDDD,
038FA3E8 add esi, 4
038FA3FE mov dword ptr [ebp+EnCryIAT], esi ;那么跳转到202这个地址
038FA40B jmp 038F7202
038FA421 rol eax, 3 ;对加密表的数据进行处理
038FA43B add eax, dword ptr [ebp+D3319B9] ;加上基地址
038FA449 cmp dword ptr [ebp+D330F15], 1
038FA450 je 038FA943
038FA476 cmp dword ptr [esi], AAAAAAAA ;A代表JMP,否则为Call
038FA47C jnz 038FA54F
038FA488 add esi, 4
038FA4A5 mov dword ptr [esi-4], 0
038FA4F4 push eax ;eax,edi交换
038FA4F5 push edi
038FA4F6 pop eax
038FA4F7 pop edi
038FA52D mov al, 0E9
038FA53F jmp 038FA589
038FA54F xor eax, edi
038FA551 xor edi, eax
038FA553 xor eax, edi
038FA573 mov al, 0E8
038FA589 push eax
038FA5B0 cmp dword ptr [ebp+D330E11], 1 ;检查FlagE11 是否1
038FA5B7 je 038FA7E6
038FA5CC mov eax,100
038FA5EA cmp dword ptr [ebp+D3E344A], 0 ;标志位Flag 44A
038FA5F1 je 038FA633
038FA5FD jmp 038FA616
038FA616 lea ebx, dword ptr [ebp+D3C4787] ;38faa71
038FA630 call ebx ; 返回后eax改变
038FA633 cmp byte ptr [edi], 90
038FA636 je 038FA66A
038FA66A cmp dword ptr [ebp+D3E354F], 0
038FA671 je 038FA72E
038FA741 mov ebx, 0
038FA766 cmp eax, 50
038FA769 jb 038FA7E6
038FA78D mov al, 90
038FA791 stos byte ptr es:[edi]
038FA79C pop eax ;上面计算的E9
038FA7D0 stos byte ptr es:[edi]
038FA8CC mov eax, dword ptr [ebp+CurAPIFunc] ; IMM32.ImmIsUIMessageA
038FA8DF sub eax, edi
038FA921 sub eax, 4 ;3行计算jmp地址
038FA92B stos dword ptr es:[edi] ;存入jmp apiaddress
038FA943 lods dword ptr [esi]
038FA954 mov dword ptr [esi-4], 0
038FA972 jmp 038FA330
038FA981 mov dword ptr [ebp+D331BD5], esi
038FA991 push edx
038FA9A0 push 8000
038FA9A6 push 0
038FA9A9 push dword ptr [ebp+D332CE9] ;5af0000
038FA9C5 call dword ptr [ebp+D331F49] ;VirtualFree ???
038FA9DF pop edx
038FA9FE mov ecx, dword ptr [ebp+D331F95]
038FAA35 mov dword ptr [ecx], 0
038FAA46 add ecx, 4
038FAA50 mov dword ptr [ebp+D331F95], ecx
038FAA5D jmp 038F6B60
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