Capture the flag (CTF)

Metasploitable: 2 - walkthrough

Metasploitable: 2 surfaced on VulnHub on June 12^th, 2012. Created by Metasploit, it can be found at https://www.vulnhub.com/entry/metasploitable-2,29/. It is the second machine in the Metasploitable series. The objective is to get root privileges.

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For the attacking machine, I will be using Kali 2017.1.

Once booted, this is what the victim machine will look like:

We start the attack by finding the IP of the victim machine by using the netdiscover command:

$ netdiscover

Now that we know our target IP, let's start by scanning the ports and try to get more information about it:

The scan shows us that the following ports are open:

• Port 21 - Running vsftpd
• Port 22 - Running OpenSSH
• Port 23 - Running telnet
• Port 25 - Running Postfix smtpd
• Port 53 - Running ISC BIND
• Port 80 - Running Apache web server
• Port 111 - Running RPC
• Port 139 - Running Samba
• Port 445 - Running Samba
• Port 512 - Running netkit-rsh
• Port 513 - Running some sort of login
• Port 514 - Running tcp-wrapped
• Port 1099 - Running JAVA RMI Registry
• Port 1524 - Running Metasploitable root shell
• Port 2049 - Running RPC
• Port 2121 - Running ProFTPD
• Port 3306 - Running MySQL
• Port 5432 - Running PostgreSQL
• Port 5900 - Running VNC
• Port 6000 - Running X11
• Port 6667 - Running UnreallRCd
• Port 8009 - Running Apache Jserv
• Port 8180 - Running Apache Tomcat

As we can see, many services are running on the machine. This is going to be interesting.

Let's start at the top. I remember Metasploit having an exploit for vsftpd. Let's see if my memory serves me right:

It is there! However, it is for version 2.3.4. Checking back at the scan results, shows us that we are in luck:

Using that exploit:

$ use exploit/unix/ftp/vsftpd_234_backdoor

$ set PAYLOAD cmd/unix/interact

Moreover, we are root! Pretty simple.

Let's see how else we can exploit this machine:

Moving on to the next port, 22 for OpenSSH. While doing some research, I found that OpenSSH 4.7p1 Debian 8ubuntu1 is vulnerable to Bruteforce. CVE 2008-0166 (https://www.rapid7.com/db/vulnerabilities/openssl-debian-weak-keys ).

For the vulnerability, I found an exploit: https://www.exploit-db.com/exploits/5632/

Let's use this and see what we get:

$ ruby ./5632.rb 172.16.92.140 root rsa/2048

Note: To test for all the files in the rsa/2048 (https://github.com/offensive-security/exploit-database-bin-sploits/raw/master/sploits/5622.tar.bz2 ) increase the THREADCOUNT in the exploit.

And a key is found. Let's try to use it and see if this works:

$ ssh -i rsa/2048/57c3115d77c56390332dc5c49978627a-5429 root@172.16.92.140

And we are root!

Note: For exploitation of Port 80, 445, 5432, and 8180 kindly refer to Metasploitable - 1: Walkthrough and the process are similar.

Moving on to Port 23, let's run Metasploit:

$ use auxiliary/scanner/telnet/telnet_version

As we can see, it shows us the credentials msfadmin:msfadmin.

$ telnet 172.16.92.140

Playing around with this shows us that msfadmin user has sudo root privileges:

Moving on to port 1099 running Java RMI registry, let' search what it gives us:

After going a basic google search, I found the following exploit: https://www.rapid7.com/db/modules/exploit/multi/misc/java_rmi_server

$ use exploit/multi/misc/java_rmi_server

And we have root!

Moving on port 5900, I tried to connect it via VNC and tried the common passwords:

$ vncviewer 172.16.92.140

It turns out that the password is "password" and we have root privileges as well.

Moving on to port 6667, we can see that UnreallRCd is running with version Unreal3.2.8.1. A basic search shows that a vulnerability is present (CVE 2010-2075) for backdoor command execution:

$ use exploit/unix/irc/unreal_ircd_3281_backdoor

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It worked and gave us root!