BUUCTF_Re_不一样的flag

无壳,ida伪代码:

int __cdecl __noreturn main(int argc, const char **argv, const char **envp)
{
  char v3[29]; // [esp+17h] [ebp-35h] BYREF
  int v4; // [esp+34h] [ebp-18h]
  int v5; // [esp+38h] [ebp-14h] BYREF
  int i; // [esp+3Ch] [ebp-10h]
  char v7[12]; // [esp+40h] [ebp-Ch] BYREF

  __main();
  v4 = 0;
  strcpy(v3, "*11110100001010000101111#");
  while ( 1 )
  {
    puts("you can choose one action to execute");
    puts("1 up");
    puts("2 down");
    puts("3 left");
    printf("4 right\n:");
    scanf("%d", &v5);
    if ( v5 == 2 )
    {
      ++*(_DWORD *)&v3[25];
    }
    else if ( v5 > 2 )
    {
      if ( v5 == 3 )
      {
        --v4;
      }
      else
      {
        if ( v5 != 4 )
LABEL_13:
          exit(1);
        ++v4;
      }
    }
    else
    {
      if ( v5 != 1 )
        goto LABEL_13;
      --*(_DWORD *)&v3[25];
    }
    for ( i = 0; i <= 1; ++i )
    {
      if ( *(int *)&v3[4 * i + 25] < 0 || *(int *)&v3[4 * i + 25] > 4 )
        exit(1);
    }
    if ( v7[5 * *(_DWORD *)&v3[25] - 41 + v4] == 49 )
      exit(1);
    if ( v7[5 * *(_DWORD *)&v3[25] - 41 + v4] == 35 )
    {
      puts("\nok, the order you enter is the flag!");
      exit(0);
    }
  }
}

 看到v3这个奇怪的字符,一共25位,然后有上下左右,

我一直在分析代码,然后想着怎么写脚本,结果,一看

5x5的迷宫,把v3分解成迷宫的样子:

*1111

01000

01010

00010

1111#

#号就是终点,*号就是起点

最后把路径转换成数字就是flag:

flag{222441144222}

posted @ 2022-01-12 19:35  Luccky  阅读(62)  评论(0编辑  收藏  举报