文章目錄
一、奇怪的TTL字段
二、答題步驟
1.二進制
2.foremost
總結
題目連結:
https://adworld.xctf.org.cn/task/task_list?type=misc&number=1&grade=1&page=4發現ttl.txt中的ttl隻有4個值63,127,191,255,寫出他們的二進制表示後發現隻有最高兩位不同
于是考慮做如下轉換,發現寫出來的16進制數開頭是ffd8,應該是jpg,于是寫入檔案中:
```csharp
fp = open('ttl.txt','r')
a = fp.readlines()
p = []
for i in a:
p.append(int(i[4:]))
s = ''
for i in p:
if i == 63:
a = '00'
elif i == 127:
a = '01'
elif i == 191:
a = '10'
elif i == 255:
a = '11'
s += a
# print(s)
import binascii
flag = ''
for i in range(0,len(s),8):
flag += chr(int(s[i:i+8],2))
flag = binascii.unhexlify(flag)
wp = open('res.jpg','wb')
wp.write(flag)
wp.close()
#00111111 63
#01111111 127
#10111111 191
#11111111 255
用foremost直接分開就好了,之後用ps拼在一塊,掃描之後得到如下資訊:
key:AutomaticKey cipher:fftu{2028mb39927wn1f96o6e12z03j58002p}
線上解密網址:
https://www.wishingstarmoye.com/ctf/autokey得到flag :
flag{2028ab39927df1d96e6a12b03e58002e}
- 二進制
- ps
- foremost