zoukankan      html  css  js  c++  java
  • 攻防世界-进阶-2-IgniteMe

    main函数代码

    int __cdecl main(int argc, const char **argv, const char **envp)
    {
      int result; // eax
      size_t i; // [esp+4Ch] [ebp-8Ch]
      char v5[4]; // [esp+50h] [ebp-88h]
      char v6[28]; // [esp+58h] [ebp-80h]
      char v7; // [esp+74h] [ebp-64h]
    
      sub_402B30(&unk_446360, "Give me your flag:");
      sub_4013F0(sub_403670);
      sub_401440(v6, 127);
      if ( strlen(v6) < 0x1E && strlen(v6) > 4 )
      {
        strcpy(v5, "EIS{");
        for ( i = 0; i < strlen(v5); ++i )
        {
          if ( v6[i] != v5[i] )
          {
            sub_402B30(&unk_446360, "Sorry, keep trying! ");
            sub_4013F0(sub_403670);
            return 0;
          }
        }
        if ( v7 == 125 )
        {
          if ( (unsigned __int8)sub_4011C0(v6) )
            sub_402B30(&unk_446360, "Congratulations! ");
          else
            sub_402B30(&unk_446360, "Sorry, keep trying! ");
          sub_4013F0(sub_403670);
          result = 0;
        }
        else
        {
          sub_402B30(&unk_446360, "Sorry, keep trying! ");
          sub_4013F0(sub_403670);
          result = 0;
        }
      }
      else
      {
        sub_402B30(&unk_446360, "Sorry, keep trying!");
        sub_4013F0(sub_403670);
        result = 0;
      }
      return result;
    }
    

    加密函数代码

    bool __cdecl sub_4011C0(char *a1)
    {
      size_t v2; // eax
      signed int v3; // [esp+50h] [ebp-B0h]
      char v4[32]; // [esp+54h] [ebp-ACh]
      int v5; // [esp+74h] [ebp-8Ch]
      int v6; // [esp+78h] [ebp-88h]
      size_t i; // [esp+7Ch] [ebp-84h]
      char v8[128]; // [esp+80h] [ebp-80h]
    
      if ( strlen(a1) <= 4 )
        return 0;
      i = 4;
      v6 = 0;
      while ( i < strlen(a1) - 1 )
        v8[v6++] = a1[i++];
      v8[v6] = 0;
      v5 = 0;
      v3 = 0;
      memset(v4, 0, 0x20u);
      for ( i = 0; ; ++i )
      {
        v2 = strlen(v8);
        if ( i >= v2 )
          break;
        if ( v8[i] >= 97 && v8[i] <= 122 )
        {
          v8[i] -= 32;
          v3 = 1;
        }
        if ( !v3 && v8[i] >= 65 && v8[i] <= 90 )
          v8[i] += 32;
        v4[i] = byte_4420B0[i] ^ sub_4013C0(v8[i]);
        v3 = 0;
      }
      return strcmp("GONDPHyGjPEKruv{{pj]X@rF", v4) == 0;
    }
    

    代码分析

     if ( v8[i] >= 97 && v8[i] <= 122 )
        {
          v8[i] -= 32;
          v3 = 1;
        }
        if ( !v3 && v8[i] >= 65 && v8[i] <= 90 )
          v8[i] += 32;
    

    大写变成小写,小写变成大写。

    return (a1 ^ 0x55) + 72;

    v4[i] = byte_4420B0[i] ^ sub_4013C0(v8[i]);
    //转变为
    v4[i] = byte_4420B0[i] ^ {(v8[i] ^ 0x55) + 72}
    //则
    v8[i]=(v4[i]^byte_4420B0[i]-72)^0x55
    //其中,需要将其转换为ASCII
    v4="GONDPHyGjPEKruv{{pj]X@rF"
    

    4420B0中的数据需要在进入十六进制视图中查看,提取出其中32位

    0D 13 17 11 02 01 20 1D 0C 02 19 2F 17 2B 24 1F
    1E 16 09 0F 15 27 13 26 0A 2F 1E 1A 2D 0C 22 04

    脚本

    分两步走, 第一步求出v8:
    for i in range(len(v4)):
    v8 += chr(((ord(v4[i]) ^ byte_4420B0[i]) - 72) ^ 0x55)
    第二部根据v8推出flag
    直接大写变成小写就可以了

  • 相关阅读:
    axios全局配置
    014 Javascript(148
    013 Javascript(134
    axios的基本使用
    axios简介
    012 Javascript(126
    016 HTML+CSS(Class198
    015 HTML+CSS(Class184
    014 HTML+CSS(Class165
    LCA题目选讲2
  • 原文地址:https://www.cnblogs.com/banpingcu/p/12683713.html
Copyright © 2011-2022 走看看