CrackMe第九题算法分析

growuphappily · 发表于 2020-2-23 19:21

本帖最后由 growuphappily 于 2020-2-23 19:23 编辑

0x00 前言

继续上一篇，开始分析算法
先回到上次爆破的地方，在段首下断点
注册，断下
算法：

[Asm] 纯文本查看 复制代码

004020AE   > \8B45 A8       mov eax,dword ptr ss:[ebp-0x58]                         ;  取出name
004020B1   .  8975 A8       mov dword ptr ss:[ebp-0x58],esi                         ;  ebp-0x58清零
004020B4   .  8B35 FC404000 mov esi,dword ptr ds:[<&MSVBVM50.__vbaVarMove>]         ;  MSVBVM50.__vbaVarMove
004020BA   .  8D55 94       lea edx,dword ptr ss:[ebp-0x6C]
004020BD   .  8D4D BC       lea ecx,dword ptr ss:[ebp-0x44]
004020C0   .  8945 9C       mov dword ptr ss:[ebp-0x64],eax
004020C3   .  C745 94 08000>mov dword ptr ss:[ebp-0x6C],0x8
004020CA   .  FFD6          call esi                                                ;  MSVBVM50.__vbaVarMove; <&MSVBVM50.__vbaVarMove>
004020CC   .  8D4D A4       lea ecx,dword ptr ss:[ebp-0x5C]
004020CF   .  FF15 B4414000 call dword ptr ds:[<&MSVBVM50.__vbaFreeObj>]            ;  MSVBVM50.__vbaFreeObj
004020D5   .  B8 01000000   mov eax,0x1
004020DA   .  8D8D 54FFFFFF lea ecx,dword ptr ss:[ebp-0xAC]
004020E0   .  8985 5CFFFFFF mov dword ptr ss:[ebp-0xA4],eax
004020E6   .  8985 4CFFFFFF mov dword ptr ss:[ebp-0xB4],eax
004020EC   .  8D55 BC       lea edx,dword ptr ss:[ebp-0x44]
004020EF   .  51            push ecx                                                ; /Step8 = NULL
004020F0   .  8D45 94       lea eax,dword ptr ss:[ebp-0x6C]                         ; |
004020F3   .  BB 02000000   mov ebx,0x2                                             ; |
004020F8   .  52            push edx                                                ; |/var18 = NULL
004020F9   .  50            push eax                                                ; ||retBuffer8 = 005ADA10
004020FA   .  899D 54FFFFFF mov dword ptr ss:[ebp-0xAC],ebx                         ; ||MSVBVM50.__vbaMidStmtVar
00402100   .  899D 44FFFFFF mov dword ptr ss:[ebp-0xBC],ebx                         ; ||计算name长度
00402106   .  FF15 18414000 call dword ptr ds:[<&MSVBVM50.__vbaLenVar>]             ; |\__vbaLenVar
0040210C   .  8D8D 44FFFFFF lea ecx,dword ptr ss:[ebp-0xBC]                         ; |
00402112   .  50            push eax                                                ; |End8 = 005ADA10
00402113   .  8D95 E8FEFFFF lea edx,dword ptr ss:[ebp-0x118]                        ; |
00402119   .  51            push ecx                                                ; |Start8 = NULL
0040211A   .  8D85 F8FEFFFF lea eax,dword ptr ss:[ebp-0x108]                        ; |
00402120   .  52            push edx                                                ; |TMPend8 = NULL
00402121   .  8D4D DC       lea ecx,dword ptr ss:[ebp-0x24]                         ; |
00402124   .  50            push eax                                                ; |TMPstep8 = 005ADA10
00402125   .  51            push ecx                                                ; |Counter8 = NULL
00402126   .  FF15 20414000 call dword ptr ds:[<&MSVBVM50.__vbaVarForInit>]         ; \__vbaVarForInit
0040212C   .  8B3D 04414000 mov edi,dword ptr ds:[<&MSVBVM50.__vbaFreeVarList>]     ;  MSVBVM50.__vbaFreeVarList
00402132   >  85C0          test eax,eax
00402134   .  0F84 9C000000 je Andréna.004021D6
0040213A   .  8D55 94       lea edx,dword ptr ss:[ebp-0x6C]
0040213D   .  8D45 DC       lea eax,dword ptr ss:[ebp-0x24]
00402140   .  52            push edx
00402141   .  50            push eax
00402142   .  C745 9C 01000>mov dword ptr ss:[ebp-0x64],0x1
00402149   .  895D 94       mov dword ptr ss:[ebp-0x6C],ebx                         ;  MSVBVM50.__vbaMidStmtVar
0040214C   .  FF15 90414000 call dword ptr ds:[<&MSVBVM50.__vbaI4Var>]              ;  MSVBVM50.__vbaI4Var
00402152   .  8D4D BC       lea ecx,dword ptr ss:[ebp-0x44]                         ; |
00402155   .  50            push eax                                                ; |Start = 0x5ADA10
00402156   .  8D55 84       lea edx,dword ptr ss:[ebp-0x7C]                         ; |
00402159   .  51            push ecx                                                ; |dString8 = NULL
0040215A   .  52            push edx                                                ; |RetBUFFER = NULL
0040215B   .  FF15 38414000 call dword ptr ds:[<&MSVBVM50.#632>]                    ; \rtcMidCharVar
00402161   .  8D45 84       lea eax,dword ptr ss:[ebp-0x7C]
00402164   .  8D4D A8       lea ecx,dword ptr ss:[ebp-0x58]                         ;  取第一位
00402167   .  50            push eax                                                ; /String8 = 005ADA10
00402168   .  51            push ecx                                                ; |ARG2 = NULL
00402169   .  FF15 70414000 call dword ptr ds:[<&MSVBVM50.__vbaStrVarVal>]          ; \__vbaStrVarVal
0040216F   .  50            push eax                                                ; /String = "?@"
00402170   .  FF15 0C414000 call dword ptr ds:[<&MSVBVM50.#516>]                    ; \转为ASCII
00402176   .  66:8985 4CFFF>mov word ptr ss:[ebp-0xB4],ax
0040217D   .  8D55 CC       lea edx,dword ptr ss:[ebp-0x34]
00402180   .  8D85 44FFFFFF lea eax,dword ptr ss:[ebp-0xBC]
00402186   .  52            push edx                                                ; /var18 = NULL
00402187   .  8D8D 74FFFFFF lea ecx,dword ptr ss:[ebp-0x8C]                         ; |
0040218D   .  50            push eax                                                ; |var28 = 005ADA10
0040218E   .  51            push ecx                                                ; |saveto8 = NULL
0040218F   .  899D 44FFFFFF mov dword ptr ss:[ebp-0xBC],ebx                         ; |MSVBVM50.__vbaMidStmtVar
00402195   .  FF15 94414000 call dword ptr ds:[<&MSVBVM50.__vbaVarAdd>]             ; \__vbaVarAdd
0040219B   .  8BD0          mov edx,eax
0040219D   .  8D4D CC       lea ecx,dword ptr ss:[ebp-0x34]
004021A0   .  FFD6          call esi                                                ;  MSVBVM50.__vbaVarMove
004021A2   .  8D4D A8       lea ecx,dword ptr ss:[ebp-0x58]
004021A5   .  FF15 B8414000 call dword ptr ds:[<&MSVBVM50.__vbaFreeStr>]            ;  MSVBVM50.__vbaFreeStr
004021AB   .  8D55 84       lea edx,dword ptr ss:[ebp-0x7C]
004021AE   .  8D45 94       lea eax,dword ptr ss:[ebp-0x6C]
004021B1   .  52            push edx
004021B2   .  50            push eax
004021B3   .  53            push ebx                                                ;  MSVBVM50.__vbaMidStmtVar
004021B4   .  FFD7          call edi                                                ;  MSVBVM50.__vbaFreeVarList
004021B6   .  83C4 0C       add esp,0xC
004021B9   .  8D8D E8FEFFFF lea ecx,dword ptr ss:[ebp-0x118]
004021BF   .  8D95 F8FEFFFF lea edx,dword ptr ss:[ebp-0x108]
004021C5   .  8D45 DC       lea eax,dword ptr ss:[ebp-0x24]
004021C8   .  51            push ecx                                                ; /TMPend8 = NULL
004021C9   .  52            push edx                                                ; |TMPstep8 = NULL
004021CA   .  50            push eax                                                ; |Counter8 = 005ADA10
004021CB   .  FF15 AC414000 call dword ptr ds:[<&MSVBVM50.__vbaVarForNext>]         ; \__vbaVarForNext
004021D1   .^ E9 5CFFFFFF   jmp Andréna.00402132
004021D6   >  8D4D CC       lea ecx,dword ptr ss:[ebp-0x34]
004021D9   .  8D95 54FFFFFF lea edx,dword ptr ss:[ebp-0xAC]
004021DF   .  51            push ecx                                                ; /var18 = NULL
004021E0   .  8D45 94       lea eax,dword ptr ss:[ebp-0x6C]                         ; |
004021E3   .  52            push edx                                                ; |var28 = NULL
004021E4   .  50            push eax                                                ; |SaveTo8 = 005ADA10
004021E5   .  C785 5CFFFFFF>mov dword ptr ss:[ebp-0xA4],0x499602D2                  ; |
004021EF   .  C785 54FFFFFF>mov dword ptr ss:[ebp-0xAC],0x3                         ; |
004021F9   .  FF15 5C414000 call dword ptr ds:[<&MSVBVM50.__vbaVarMul>]             ; \__vbaVarMul
004021FF   .  8BD0          mov edx,eax
00402201   .  8D4D CC       lea ecx,dword ptr ss:[ebp-0x34]
00402204   .  FFD6          call esi                                                ;  MSVBVM50.__vbaVarMove
00402206   .  8B1D A0414000 mov ebx,dword ptr ds:[<&MSVBVM50.__vbaMidStmtVar>]      ;  MSVBVM50.__vbaMidStmtVar
0040220C   .  8D4D CC       lea ecx,dword ptr ss:[ebp-0x34]
0040220F   .  51            push ecx
00402210   .  6A 04         push 0x4
00402212   .  8D95 54FFFFFF lea edx,dword ptr ss:[ebp-0xAC]
00402218   .  6A 01         push 0x1
0040221A   .  52            push edx
0040221B   .  C785 5CFFFFFF>mov dword ptr ss:[ebp-0xA4],Andréna.00401C34            ;  UNICODE "-"
00402225   .  C785 54FFFFFF>mov dword ptr ss:[ebp-0xAC],0x8
0040222F   .  FFD3          call ebx                                                ;  MSVBVM50.__vbaMidStmtVar; <&MSVBVM50.__vbaMidStmtVar>
00402231   .  8D45 CC       lea eax,dword ptr ss:[ebp-0x34]
00402234   .  8D8D 54FFFFFF lea ecx,dword ptr ss:[ebp-0xAC]
0040223A   .  50            push eax
0040223B   .  6A 09         push 0x9
0040223D   .  6A 01         push 0x1
0040223F   .  51            push ecx
00402240   .  C785 5CFFFFFF>mov dword ptr ss:[ebp-0xA4],Andréna.00401C34            ;  UNICODE "-"
0040224A   .  C785 54FFFFFF>mov dword ptr ss:[ebp-0xAC],0x8
00402254   .  FFD3          call ebx                                                ;  MSVBVM50.__vbaMidStmtVar
00402256   .  8B45 08       mov eax,dword ptr ss:[ebp+0x8]
00402259   .  50            push eax
0040225A   .  8B10          mov edx,dword ptr ds:[eax]                              ;  Andréna.004032F0
0040225C   .  FF92 04030000 call dword ptr ds:[edx+0x304]
00402262   .  50            push eax
00402263   .  8D45 A4       lea eax,dword ptr ss:[ebp-0x5C]
00402266   .  50            push eax
00402267   .  FF15 24414000 call dword ptr ds:[<&MSVBVM50.__vbaObjSet>]             ;  MSVBVM50.__vbaObjSet
0040226D   .  8BD8          mov ebx,eax
0040226F   .  8D55 A8       lea edx,dword ptr ss:[ebp-0x58]
00402272   .  52            push edx
00402273   .  53            push ebx                                                ;  MSVBVM50.__vbaMidStmtVar
00402274   .  8B0B          mov ecx,dword ptr ds:[ebx]
00402276   .  FF91 A0000000 call dword ptr ds:[ecx+0xA0]
0040227C   .  85C0          test eax,eax
0040227E   .  7D 12         jge short Andréna.00402292
00402280   .  68 A0000000   push 0xA0
00402285   .  68 201C4000   push Andréna.00401C20
0040228A   .  53            push ebx                                                ;  MSVBVM50.__vbaMidStmtVar
0040228B   .  50            push eax
0040228C   .  FF15 14414000 call dword ptr ds:[<&MSVBVM50.__vbaHresultCheckObj>]    ;  MSVBVM50.__vbaHresultCheckObj
00402292   >  8B45 A8       mov eax,dword ptr ss:[ebp-0x58]
00402295   .  8D4D CC       lea ecx,dword ptr ss:[ebp-0x34]
00402298   .  8945 9C       mov dword ptr ss:[ebp-0x64],eax
0040229B   .  8D45 94       lea eax,dword ptr ss:[ebp-0x6C]
0040229E   .  50            push eax                                                ; /var18 = 005ADA10
0040229F   .  51            push ecx                                                ; |var28 = NULL
004022A0   .  C745 A8 00000>mov dword ptr ss:[ebp-0x58],0x0                         ; |
004022A7   .  C745 94 08800>mov dword ptr ss:[ebp-0x6C],0x8008                      ; |
004022AE   .  FF15 48414000 call dword ptr ds:[<&MSVBVM50.__vbaVarTstEq>]           ; \__vbaVarTstEq

看起来令人头疼。。VB的函数很奇怪，返回值不放eax非要放ebp-0x34
继续跟，看到了一个可疑的字符串：“177-6049-2150”
把它放进注册码试试
结果注册成功！
也就是说，growuphappily的注册码就是177-6049-2150！
然而，我分析了一小时，没有结果
我最终决定，，还是放进VB反编译器吧。。。

[Visual Basic] 纯文本查看 复制代码

Private Sub Command1_Click() '401FF0
  loc_00402092: var_58 = Text2.Text
  loc_004020CA: var_44 = var_58
  loc_00402126: For var_24 = 1 To Len(var_44) Step 1
  loc_00402132: 
  loc_00402134: If var_108 = 0 Then GoTo loc_004021D6
  loc_00402169: var_58 = CStr(Mid(var_44, CLng(var_24), 1))
  loc_00402176: var_B4 = Asc(var_58)
  loc_004021A0: var_34 = var_34 + Asc(var_58)
  loc_004021CB: Next var_24
  loc_004021D1: GoTo loc_00402132
  loc_004021D6: 'Referenced from: 00402134
  loc_00402204: var_34 = var_34 * 1234567890
  loc_0040222F: call ebx(8, 00000001h, 00000004h, var_34, var_108, var_118, Me, undef 'Ignore this '__vbaFreeVarList, %ecx = %S_edx_S, 004041A0h)
  loc_00402254: call ebx(8, 00000001h, 00000009h, var_34)
  loc_00402276: var_58 = Text1.Text
  loc_00402298: var_64 = var_58
  loc_004022CB: If (var_58 = var_34) = 0 Then GoTo loc_00402391
  loc_004022D1: Beep
  loc_00402308: var_B4 = "对了！"
  loc_00402327: var_A4 = "  RiCHTiG !!!!   ....  weiter mit dem N&#228;chsten !!!"
  loc_00402374: var_54 = MsgBox("  RiCHTiG !!!!   ....  weiter mit dem N&#228;chsten !!!", 48, "对了！", 10, 10)
  loc_0040238C: GoTo loc_00402446
  loc_00402391: 'Referenced from: 004022CB
  loc_004023C2: var_B4 = "抱歉，这不对！"
  loc_004023E1: var_A4 = "可惜，错了，如果你做不到，那就E-Mail我在 [url=mailto:xxxxxxxxxx@xxx.xxx]xxxxxxxxxx@xxx.xxx[/url](脱敏)"
  loc_0040242E: var_54 = MsgBox("可惜，错了，如果你做不到，那就E-Mail我在 [url=mailto:xxxxxxxxxx@xxx.xxx]xxxxxxxxxx@xxx.xxx[/url](脱敏)", 16, "抱歉，这不对！", 10, 10)
  loc_00402446: 'Referenced from: 0040238C
  loc_00402459: GoTo loc_0040248F
  loc_0040248E: Exit Sub
  loc_0040248F: 'Referenced from: 00402459
  loc_004024C0: GoTo loc_00esi
End Sub

可以看出，就是把Name每个字符的ASCII加在一起再乘以1234567890
然后中间的那两个call不知道是干什么用的
先算出前面几步操作得出的值结果为1771604922150
再与注册码对比：177-6049-2150
这不就是把第四位，第九位换成‘-’了吗！
上注册机：

[Python] 纯文本查看 复制代码

a = 0
for i in input('请输入你的名字:'):
    a += ord(i)
a *= 1234567890
key = ''
for i in range(len(str(a))):
    if i in [3,8]:
        key += '-'
        continue
    key += str(a)[i]
print(key)

0x03 最后

评分不要钱！评分不要钱！评分不要钱！

solly · 发表于 2020-2-25 11:53

中间两个call是VB函数 MID()
Mid(sn, 4, 1) = "-"
Mid(sn, 9, 1) = "-"
就是把4、9位换成“-”号

chenjingyes · 发表于 2020-2-23 22:46

谢谢楼主分享

qianyu666 · 发表于 2020-2-24 00:53

有点难度

lateday · 发表于 2020-2-24 09:02

Mark一下，太强了

lzz2592 · 发表于 2020-2-24 09:09

进来学习一下。

nj2004 · 发表于 2020-2-24 09:14

厉害?，好好学习

reagan_he · 发表于 2020-2-24 09:16

谢谢分享

deity1314 · 发表于 2020-2-24 09:22

进来学习一下。

hua111 · 发表于 2020-2-24 09:42

每天认真看

yaoyao7 · 发表于 2020-2-24 10:12

需要好好消化一下感谢分享

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[原创] CrackMe第九题算法分析

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