【Root-Me】 Uncompress me

解题报告 CTF Root-Me Programming
CTF
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发布日期:   2019-07-11
更新日期:   2024-11-17
文章字数:   1.6k
阅读时长:   8 分
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水题四连，与 Go back to college 、Encoded string 、The Roman’s wheel 一模一样的解题方法，只是跟 robot 的交互消息改变了而已。

可以去参考 Encoded string 的解题报告，这两题的代码基本一模一样，只是多了一步解压而已。

题目已经明确告知是 zlib 压缩 + Base64 编码，并给出了样例，经测试，处理顺序为：

eJxzrHItCqn0zC8AABBiA2g= => Base64 解码 => zlib 解压 => AzErTyIop

换言之我们需要对 robot 给出的字符串先做 Base64 解码，再做 zlib 解压。

解题代码贴在下面（python 版本为 3.5.2）：

#!/usr/bin/python
# -*- coding: UTF-8 -*-

import zlib
import base64
import re
import socket
CHARSET = 'utf-8'



def send_cmd(irc_sock, cmd) :
    """
    发送命令到 IRC 服务器

    Args:
        irc_sock: 与 IRC 服务器的 socket 连接
        cmd: 待发送的命令（不需 \r\n 结束符，会自动补全）

    Returns:
        None
    """

    print('  =>  %s' % cmd)
    irc_sock.send(('%s\r\n' % cmd).encode(CHARSET))
    return


def send_msg(irc_sock, to, msg) :
    """
    发送 PRIVMSG 私信命令到 IRC 服务器

    Args:
        irc_sock: 与 IRC 服务器的 socket 连接
        to: 接收私信的对象
        msg: 待发送的私信内容

    Returns:
        None
    """

    cmd = 'PRIVMSG %s :%s' % (to, msg)
    send_cmd(irc_sock, cmd)
    return


def conn_irc(irc_host, irc_port, irc_chan, username, anywords) :
    """
    连接到 IRC 服务器的指定聊天频道

    Args:
        irc_host: IRC 服务器主机
        irc_port: IRC 服务端口
        irc_chan: IRC 聊天频道
        username: 在 IRC 聊天室标识自己身份的昵称（任意值均可，只要未被他人在 IRC 上使用即可）
        anywords: 首次加入 IRC 聊天室后用于打招呼的语句，任意即可

    Returns:
        irc_sock: 与 IRC 服务器的 socket 连接
    """

    irc_sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    irc_sock.connect((irc_host, irc_port))

    # NICK 和 USER 命令必须先发送，以声明自己身份
    # （注意同一个 IP 不能同时开两次以上的连接，否则只有第一次能够注册成功）
    send_cmd(irc_sock, 'NICK %s' % username)
    send_cmd(irc_sock, 'USER %s %s %s :%s' % (username, username, username, anywords))
    send_cmd(irc_sock, 'JOIN %s' % irc_chan)    # 加入频道
    return irc_sock



def interface(irc_sock, bot_name, username) :
    """
    在 IRC 聊天室与 robot 进行消息交互

    Args:
        irc_sock: 与 IRC 服务器的 socket 连接
        bot_name: 机器人的昵称
        username: 自己的昵称

    Returns:
        None
    """

    finish = False
    while finish == False :
        rsp_data = irc_sock.makefile(encoding=CHARSET)

        # 逐行解析响应数据
        for line in rsp_data:
            print(line, end='')

            if line.startswith('PING') :
                send_cmd(irc_sock, line.replace('PING', 'PONG'))

            # :EXP!EXP@hzv-tsd.o51.eaqa1b.IP MODE EXP +x
            elif line.startswith(':%s' % username) :
                send_msg(irc_sock, bot_name, '!ep4')

            # :Candy!Candy@root-me.org PRIVMSG EXP :eJyLyvIui/DKdw8IMvQyN/GxLDA0zDStCDaIdPY1AgCAhQhx
            elif line.startswith(':%s' % bot_name) :
                mth = re.match(r':.+?:(\S+)$', line)
                if mth :
                    cipher = mth.group(1)
                    zip_byte = base64.b64decode(cipher)     # base64 解码
                    byte = zlib.decompress(zip_byte)        # zlib 解压
                    plain = bytes.decode(byte, CHARSET)     # byte 转字符串
                    send_msg(irc_sock, bot_name, '!ep4 -rep %s' % plain)

                else :
                    send_cmd(irc_sock, 'QUIT')  # 退出聊天频道
                    finish = True
                    break
    return


if __name__ == '__main__' :
    irc_host = 'irc.root-me.org'
    irc_port = 6667
    irc_chan = '#root-me_challenge'
    bot_name = 'Candy'
    username = 'EXP'
    anywords = 'http://exp-blog.com'

    # 连接到 ROOTME 的 IRC 聊天室并加入 CHALLENGE 聊天频道
    irc_sock = conn_irc(irc_host, irc_port, irc_chan, username, anywords)

    # 在聊天室与 robot 进行消息交互
    interface(irc_sock, bot_name, username)

    # 关闭 IRC 的 socket 连接
    irc_sock.shutdown(2)
    irc_sock.close()

运行代码后，结果如下：

# uncompress_me.py
  =>  NICK EXP
  =>  USER EXP EXP EXP :http://exp-blog.com
  =>  JOIN #root-me_challenge
:irc.hackerzvoice.net NOTICE Auth :*** Looking up your hostname...
:irc.hackerzvoice.net 451 JOIN :You have not registered
:irc.hackerzvoice.net NOTICE Auth :*** Could not resolve your hostname: Domain name not found; using your IP address (223.74.73.34) instead.
:irc.hackerzvoice.net NOTICE Auth :Welcome to HackerzVoice!
:irc.hackerzvoice.net 001 EXP :Welcome to the HackerzVoice IRC Network EXP!EXP@223.74.73.34
:irc.hackerzvoice.net 002 EXP :Your host is irc.hackerzvoice.net, running version InspIRCd-2.0
:irc.hackerzvoice.net 003 EXP :This server was created 19:52:09 Aug 12 2013
:irc.hackerzvoice.net 004 EXP irc.hackerzvoice.net InspIRCd-2.0 BHIRSWcghiorswx FLMNPRSYabcefhijklmnopqrstvz FLYabefhjkloqv
:irc.hackerzvoice.net 005 EXP AWAYLEN=200 CALLERID=g CASEMAPPING=rfc1459 CHANMODES=be,k,FLfjl,MNPRScimnprstz CHANNELLEN=64 CHANTYPES=# CHARSET=ascii ELIST=MU EXCEPTS=e EXTBAN=,NRSUcjmz FNC KICKLEN=255 MAP :are supported by this server
:irc.hackerzvoice.net 005 EXP MAXBANS=60 MAXCHANNELS=20 MAXPARA=32 MAXTARGETS=20 MODES=20 NETWORK=HackerzVoice NICKLEN=31 OVERRIDE PREFIX=(Yqaohv)!~&@%+ SECURELIST SSL=0.0.0.0:6697 STARTTLS STATUSMSG=!~&@%+ :are supported by this server
:irc.hackerzvoice.net 005 EXP TOPICLEN=307 USERIP VBANLIST WALLCHOPS WALLVOICES :are supported by this server
:irc.hackerzvoice.net 042 EXP 959AAVARW :your unique ID
:irc.hackerzvoice.net 375 EXP :irc.hackerzvoice.net message of the day
:irc.hackerzvoice.net 372 EXP :-     ██████████     ╻ ╻┏━┓┏━╸╻┏ ┏━╸┏━┓╺━┓╻ ╻┏━┓╻┏━╸┏━╸
:irc.hackerzvoice.net 372 EXP :-   ████████    ██   ┣━┫┣━┫┃  ┣┻┓┣╸ ┣┳┛┏━┛┃┏┛┃ ┃┃┃  ┣╸ 
:irc.hackerzvoice.net 372 EXP :-   ██    ██    ██   ╹ ╹╹ ╹┗━╸╹ ╹┗━╸╹┗╸┗━╸┗┛ ┗━┛╹┗━╸┗━╸
:irc.hackerzvoice.net 372 EXP :-   ██████████████   
:irc.hackerzvoice.net 372 EXP :-     ██████████     IRC network at irc.hackerzvoice.net.
:irc.hackerzvoice.net 372 EXP :-     ██  ██  ██     HZV will never die.
:irc.hackerzvoice.net 372 EXP :- 
:irc.hackerzvoice.net 372 EXP :- 
:irc.hackerzvoice.net 372 EXP :- Bienvenue sur l'irc HackerzVoice !
:irc.hackerzvoice.net 372 EXP :- ==================================
:irc.hackerzvoice.net 372 EXP :- 
:irc.hackerzvoice.net 372 EXP :- - Besoin d'aide ? Rejoignez nous sur #help : /join #help
:irc.hackerzvoice.net 372 EXP :- 
:irc.hackerzvoice.net 372 EXP :- ----- Règles du serveur --------------------------------------
:irc.hackerzvoice.net 372 EXP :-  [+] No flooding
:irc.hackerzvoice.net 372 EXP :-  [+] No DoS bots
:irc.hackerzvoice.net 372 EXP :-  [+] No clones
:irc.hackerzvoice.net 372 EXP :-  [+] No spamming
:irc.hackerzvoice.net 372 EXP :-  [+] No takeovers
:irc.hackerzvoice.net 372 EXP :-  [+] No whiners
:irc.hackerzvoice.net 372 EXP :- --------------------------------------------------------------
:irc.hackerzvoice.net 372 EXP :- 
:irc.hackerzvoice.net 372 EXP :- Il est possible de se connecter à ce serveur :
:irc.hackerzvoice.net 372 EXP :- - irc.hackerzvoice.net:6667
:irc.hackerzvoice.net 372 EXP :- - irc.hackerzvoice.net:6697 (SSL)
:irc.hackerzvoice.net 372 EXP :- 
:irc.hackerzvoice.net 372 EXP :- ### Contact
:irc.hackerzvoice.net 372 EXP :- 
:irc.hackerzvoice.net 372 EXP :- Admin : Hackira (hackira@hzv.fr)
:irc.hackerzvoice.net 372 EXP :- 
:irc.hackerzvoice.net 372 EXP :- #### Sites web
:irc.hackerzvoice.net 372 EXP :- - https://www.hackerzvoice.net/
:irc.hackerzvoice.net 372 EXP :- - https://www.lehack.org/
:irc.hackerzvoice.net 372 EXP :- 
:irc.hackerzvoice.net 372 EXP :- #### Réseaux sociaux
:irc.hackerzvoice.net 372 EXP :- - Twitter : https://www.twitter.com/asso_hzv
:irc.hackerzvoice.net 376 EXP :End of message of the day.
:irc.hackerzvoice.net 251 EXP :There are 244 users and 85 invisible on 2 servers
:irc.hackerzvoice.net 252 EXP 2 :operator(s) online
:irc.hackerzvoice.net 254 EXP 106 :channels formed
:irc.hackerzvoice.net 255 EXP :I have 309 clients and 1 servers
:irc.hackerzvoice.net 265 EXP :Current Local Users: 309  Max: 355
:irc.hackerzvoice.net 266 EXP :Current Global Users: 329  Max: 375
:irc.hackerzvoice.net 396 EXP hzv-9ks.o51.eaqa1b.IP :is now your displayed host
:EXP!EXP@hzv-9ks.o51.eaqa1b.IP MODE EXP +x
  =>  PRIVMSG Candy :!ep4
:Candy!Candy@root-me.org PRIVMSG EXP :eJyLyvIui/DKdw8IMvQyN/GxLDA0zDStCDaIdPY1AgCAhQhx
  =>  PRIVMSG Candy :!ep4 -rep ZjKvXJoGPR1J74L9p11i5xS0YCM2
:Candy!Candy@root-me.org PRIVMSG EXP :You dit it! You can validate the challenge with the password tumasp0wned
  =>  QUIT

Process finished with exit code 0

其实前面一大段 :irc.hackerzvoice.net ****** 都是连接到 IRC 聊天室后自动返回的画屏信息，最后几行才是真正的交互内容。显然地，我计算出了结果并成功得到了密码。

注：若网络不好导致 2秒内 没有发送成功， IRC 会提示 too late ，多试几次就好

答案下载

flag 下载后的 flagzip 的文件需要手动更改后缀为 *.zip，然后解压即可（为了避免直接刷答案）

文章作者: EXP
文章链接: https://exp-blog.com/safe/ctf/rootme/programming/uncompress-me/
版权声明: 本博客所有文章除特別声明外，均采用 CC BY 4.0 许可协议。转载请注明来源 EXP !
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