[RoarCTF2019] TankGame

不多说，用dnspy反编译data文件夹中的Assembly-CSharp文件

使用分析器分析一下可疑的FlagText 发现其在WinGame中被调用，跟进WinGame函数

public static void WinGame()
 {
     if (!MapManager.winGame && (MapManager.nDestroyNum == 4 || MapManager.nDestroyNum == 5))
     {
         string text = "clearlove9";
         for (int i = 0; i < 21; i++)
         {
             for (int j = 0; j < 17; j++)
             {
                 text += MapManager.MapState[i, j].ToString();
             }
         }
         string a = MapManager.Sha1(text);
         if (a == "3F649F708AAFA7A0A94138DC3022F6EA611E8D01")
         {
             FlagText._instance.gameObject.SetActive(true);
             FlagText.str = "RoarCTF{wm-" + MapManager.Md5(text) + "}";
             MapManager.winGame = true;
         }
     }
 }

拿flag逻辑很简单，如果被摧毁的方块数为4或5且此时游戏没有结束，那么遍历21x17的某数组尽数加入某字符串。判断sha1(“clearlove9”+mapstate)是否为指定值，如果是则flag为"RoarCTF{wm-" + MapManager.Md5(text) + "}"，这个md5是“clearlove9”+mapdata的md5的前十个字符。

MapState为游戏当前的地图数据，观察游戏初始时的地图数据（21x17）和我们游戏地图相比对得出：

?

8 空的
1 砖头
4 水
5 草
2 钢铁
0 家（炸了之后就是9）

?其中只有砖头和家可以打碎，打碎后砖头变成空（1）家打碎了就gg了。接下来写脚本遍历所有情况即可(python2环境下运行，python3 hashlib的要求不同，该脚本会报错)。

import hashlib
data = [
    [8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8],
    [8, 8, 4, 5, 8, 1, 1, 1, 1, 1, 1, 8, 8, 8, 8, 4, 8],
    [8, 2, 8, 1, 8, 8, 5, 1, 8, 8, 8, 1, 8, 1, 8, 4, 8],
    [8, 5, 8, 2, 8, 8, 8, 8, 1, 8, 8, 4, 8, 1, 1, 5, 8],
    [8, 8, 8, 8, 2, 4, 8, 1, 1, 8, 8, 1, 8, 5, 1, 5, 8],
    [8, 8, 8, 8, 5, 8, 8, 1, 5, 1, 8, 8, 8, 1, 8, 8, 8],
    [8, 8, 8, 1, 8, 8, 8, 8, 8, 8, 8, 8, 1, 8, 1, 5, 8],
    [8, 1, 8, 8, 1, 8, 8, 1, 1, 4, 8, 8, 8, 8, 8, 1, 8],
    [8, 4, 1, 8, 8, 5, 1, 8, 8, 8, 8, 8, 4, 2, 8, 8, 8],
    [1, 1, 8, 5, 8, 2, 8, 5, 1, 4, 8, 8, 8, 1, 5, 1, 8],
    [9, 1, 4, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8],
    [1, 1, 8, 1, 8, 8, 2, 1, 8, 8, 5, 2, 1, 8, 8, 8, 8],
    [8, 8, 8, 8, 4, 8, 8, 2, 1, 1, 8, 2, 1, 8, 1, 8, 8],
    [8, 1, 1, 8, 8, 4, 4, 1, 8, 4, 2, 4, 8, 4, 8, 8, 8],
    [8, 4, 8, 8, 1, 2, 8, 8, 8, 8, 1, 8, 8, 1, 8, 1, 8],
    [8, 1, 1, 5, 8, 8, 8, 8, 8, 8, 8, 8, 1, 8, 8, 8, 8],
    [8, 8, 1, 1, 5, 2, 8, 8, 8, 8, 8, 8, 8, 8, 2, 8, 8],
    [8, 8, 4, 8, 1, 8, 2, 8, 1, 5, 8, 8, 4, 8, 8, 8, 8],
    [8, 8, 2, 8, 1, 8, 8, 1, 8, 8, 1, 8, 2, 2, 5, 8, 8],
    [8, 2, 1, 8, 8, 8, 8, 2, 8, 4, 5, 8, 1, 1, 2, 5, 8],
    [8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8]
]
text = ''
for i in range(21):
    for j in range(17):
        text += str(data[i][j])
text = list(text)
def work(data,index,num):
    if num == 3:
        temp=''.join(data)
        if hashlib.sha1('clearlove9'+temp).hexdigest() == '3f649f708aafa7a0a94138dc3022f6ea611e8d01':
            key=hashlib.md5('clearlove9'+temp).hexdigest().upper()[:10]
            flag="RoarCTF{wm-"+key+"}"
            print(flag)
        return
    if index == 21*17:
        return
    if data[index] =='1':
        temp=list(data)
        temp[index]='8'
        work(temp,index+1,num+1)
    work(data,index+1,num)

if __name__ == "__main__":
    work(text,0,0)