BUUCTF re/[ACTF新生赛2020]Oruga

[ACTF新生赛2020]Oruga

进入sub_78A函数，查看主要逻辑



打印迷宫，并确定结果

data=[0, 0, 0, 0, 0x23, 0, 0, 0, 0, 0, 0, 0, 0x23, 0x23, 0x23, 0x23, 0, 0, 0, 0x23, 0x23, 0, 0, 0, 0x4F, 0x4F, 0,
      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x4F, 0x4F, 0, 0x50, 0x50, 0, 0, 0, 0, 0, 0, 0x4C, 0, 0x4F, 0x4F,
      0, 0x4F, 0x4F, 0, 0x50, 0x50, 0, 0, 0, 0, 0, 0, 0x4C, 0, 0x4F, 0x4F, 0, 0x4F, 0x4F, 0, 0x50, 0, 0, 0, 0, 0,
      0, 0x4C, 0x4C, 0, 0x4F, 0x4F, 0, 0, 0, 0, 0x50, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x4F, 0x4F, 0, 0, 0, 0, 0x50, 0,
      0, 0, 0, 0x23, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x23,
      0, 0, 0, 0, 0, 0, 0, 0, 0, 0x4D, 0x4D, 0x4D, 0, 0, 0, 0x23, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x4D, 0x4D, 0x4D,
      0, 0, 0, 0, 0x45, 0x45, 0, 0, 0, 0x30, 0, 0x4D, 0, 0x4D, 0, 0x4D, 0, 0, 0, 0, 0x45, 0, 0, 0, 0, 0, 0, 0,
      0, 0, 0, 0, 0, 0, 0, 0, 0x45, 0x45, 0x54, 0x54, 0x54, 0x49, 0, 0x4D, 0, 0x4D, 0, 0x4D, 0, 0, 0, 0, 0x45, 0,
      0, 0x54, 0, 0x49, 0, 0x4D, 0, 0x4D, 0, 0x4D, 0, 0, 0, 0, 0x45, 0, 0, 0x54, 0, 0x49, 0, 0x4D, 0, 0x4D, 0, 0x4D,
      0x21, 0, 0, 0, 0x45, 0x45]
i=0
j=0
flag=""
for i in range(0,16):
      for j in range(0,16):
            if (data[i * 16 + j] == 0):
                  flag+='0'
            else:
                  if (data[i * 16 + j] == 33):
                        flag+='#'
                  else:
                        flag+='*'
      flag+='\n'
print(flag)

flag{MEWEWEMJM}

总结：

1. 意识到是迷宫，但是没有意识到16*16的情况下，上下移动只需要加减16即可
2. 没有意识到（unsigned int）类型转换后结果一定为正数，所以若v2-240<0时溢出为正数