UNCTF-日常训练-reverse-easyMaze

没有加壳，主函数也很简洁

int __cdecl main(int argc, const char **argv, const char **envp)
{
  char v5[512]; // [rsp+20h] [rbp-60h] BYREF
  char v6[512]; // [rsp+220h] [rbp+1A0h] BYREF

  sub_401AC0(argc, argv, envp);
  memset(v6, 0, sizeof(v6));
  memset(v5, 0, sizeof(v5));
  puts("Help Me Out!!!!!!!!");
  sub_40AE30("%200s", v6);
  if ( sub_401757(v6) && (unsigned __int8)sub_40161A((__int64)&v6[6]) )
    puts("Yes! Escaped!");
  else
    puts("No way!");
  return 0;
}



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一个验证flag格式

_BOOL8 __fastcall sub_401757(const char *a1)
{
  return !strncmp(a1, "unctf{", 6ui64) && a1[strlen(a1) - 1] == '}';
}
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另一个判断路径

__int64 __fastcall sub_40161A(__int64 a1)
{
  int v1; // eax
  int v3; // [rsp+24h] [rbp-Ch]
  int v4; // [rsp+28h] [rbp-8h]
  int v5; // [rsp+2Ch] [rbp-4h]

  v5 = 0;
  v4 = 0;
  v3 = 0;
  while ( 1 )
  {
    v1 = *(char *)(a1 + v5);
    if ( v1 == 100 )
    {
      ++v4;
    }
    else if ( v1 > 100 )
    {
      if ( v1 == 115 )
      {
        ++v3;
      }
      else
      {
        if ( v1 != 119 )
          return 0i64;
        --v3;
      }
    }
    else
    {
      if ( v1 != 97 )
        return 0i64;
      --v4;
    }
    if ( v4 < 0
      || v3 < 0
      || *((_BYTE *)qword_40F030 + 10 * v3 + v4) == 68
      || *((_BYTE *)qword_40F030 + 10 * v3 + v4) == 48 )
    {
      return 0i64;
    }
    if ( v4 > 9 || v3 > 9 )
      return 0i64;
    if ( *((_BYTE *)qword_40F030 + 10 * v3 + v4) == 83 )
      break;
    if ( (unsigned __int8)sub_4019F4() )
    {
      puts("I See YOU!");
      exit(2);
    }
    ++v5;
  }
  return 1i64;
}
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这里是判断是否走到终点 qword_40F030中存的就是地图数据

  if ( v4 < 0
      || v3 < 0
      || *((_BYTE *)qword_40F030 + 10 * v3 + v4) == 'D'
      || *((_BYTE *)qword_40F030 + 10 * v3 + v4) == '0')
    {
      return 0i64;
    }
    if ( v4 > 9 || v3 > 9 )
      return 0i64;
    if ( *((_BYTE *)qword_40F030 + 10 * v3 + v4) == 'S' )
      break;
    if ( (unsigned __int8)sub_4019F4() )        // 检测debug
    {
      puts("I See YOU!");
      exit(2);
    }
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按x交叉引用找到给其赋值的地方

char *sub_4017AA()
{
  _QWORD *v0; // rax
  char *result; // rax
  __int64 v2[14]; // [rsp+20h] [rbp-70h] BYREF

  qmemcpy(
    v2,
    "Oo00oD00SD0oooo0Doooo0D0oD0o00ooooo00o00oD0D0oooooo00o0o0o0ooDoooooDDDo00o00oooooD0D0000oDoooooooooD",
    100);
  qword_40F030 = malloc(0x80ui64);
  memset(qword_40F030, 0, 0x80ui64);
  v0 = qword_40F030;
  *(_QWORD *)qword_40F030 = v2[0];
  v0[1] = v2[1];
  v0[2] = v2[2];
  v0[3] = v2[3];
  v0[4] = v2[4];
  v0[5] = v2[5];
  v0[6] = v2[6];
  v0[7] = v2[7];
  v0[8] = v2[8];
  v0[9] = v2[9];
  v0[10] = v2[10];
  v0[11] = v2[11];
  *((_DWORD *)v0 + 24) = v2[12];
  result = (char *)qword_40F030 + 100;
  *((_BYTE *)qword_40F030 + 100) = 0;
  return result;
}
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分析下，ws上下，ad左右，左上角是起始点，S是终点 o是可以走的路径

Oo00oD00SD
0oooo0Dooo
o0D0oD0o00
ooooo00o00
oD0D0ooooo
o00o0o0o0o
oDoooooDDD
o00o00oooo
oD0D0000oD
oooooooooD
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手动走一下：dsdddssaaaassssssddddddddwwaawawwddwwwdw

最终flag： unctf{dsdddssaaaassssssddddddddwwaawawwddwwwdw}