BUUCTF misc 专题（99）[SWPU2019]Network

下载附件，是个txt文件

发现是TTL隐写，直接用脚本跑

import binascii
with open('attachment.txt','r') as fp:
    a=fp.readlines()
    p=[]
    for x in range(len(a)):
       p.append(int(a[x])) 
    s=''
    for i in p:
        if(i==63):
            b='00'
        elif(i==127):
            b='01'
        elif(i==191):
            b='10'
        else:
            b='11'
        s +=b
# print(s)
flag = ''
for i in range(0,len(s),8):
    flag += chr(int(s[i:i+8],2))
flag = binascii.unhexlify(flag)
wp = open('ans.zip','wb')
wp.write(flag)
wp.close()

打开跑出来的ans.zip压缩包，发现需要密码，猜测是伪加密

修改9为0保存后打开txt文件，发现应该是base64的套娃，脚本解密

# -*- encoding: utf-8 -*-
import base64

f = open('flag.txt','rb').read()
while True:
    f = base64.b64decode(f)
    if b'{' in f:
        print(f)
        break
    else:
        continue

 我这里是放在虚拟机里面跑的

flag{189ff9e5b743ae95f940a6ccc6dbd9ab}