Class: PdfScanner::Scanner

Inherits:
Object
  • Object
show all
Defined in:
lib/pdf_scanner/scanner.rb

Constant Summary collapse

DEFAULT_CONFIG_FILE = 
"#{File.dirname(__FILE__)}/config/pdfcop.conf.yml"
DEFAULT_POLICY = 
"standard"
SECURITY_POLICIES = 
{}
ANNOTATION_RIGHTS = 
{
  FileAttachment: i[allowAttachments allowFileAttachmentAnnotation],
  Sound: i[allowSoundAnnotation],
  Movie: i[allowMovieAnnotation],
  Screen: i[allowScreenAnnotation],
  Widget: i[allowAcroforms],
  RichMedia: i[allowRichMediaAnnotation],
  :"3D" => i[allow3DAnnotation]
}

Instance Method Summary collapse

Constructor Details

#initialize(params = {}) ⇒ Scanner 



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# File 'lib/pdf_scanner/scanner.rb', line 23

def initialize(params = {})
  @options = {}
  @options[:output_log] = params[:output_log] if params[:output_log].present?
  @options[:target_file] = params[:target_file] if params[:target_file].present?
  @options[:config_file] = params[:config_file] if params[:config_file].present?
  @options[:policy] = params[:policy] if params[:policy].present?
  @options[:move_dir] = params[:dir] if params[:dir].present?
  @options[:password] = params[:passwd] if params[:passwd].present? # for encrypted file
  @errors = { rejected_policies: [], analysis_failure: [] }
end

Instance Method Details

#analyze_3d_annotation(annot) ⇒ Object 



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# File 'lib/pdf_scanner/scanner.rb', line 224

def analyze_3d_annotation(annot)
  # 3D annotation might pull in JavaScript for real-time driven behavior.
  return unless annot.key?(:"3DD")

  dd = annot[:"3DD"].solve
  u3dstream = nil

  case dd
  when Origami::Stream
      u3dstream = dd
  when Origami::Dictionary
      u3dstream = dd[:"3DD"].solve
  end

  if u3dstream.is_a?(Stream) and u3dstream.key?(:OnInstantiate)
    check_rights(:allowJS)

    if annot.key?(:"3DA") # is 3d view instantiated automatically?
      u3dactiv = annot[:"3DA"].solve

      check_rights(:allowJSAtOpening) if u3dactiv.is_a?(Origami::Dictionary) and (u3dactiv.A == :PO or u3dactiv.A == :PV)
    end
  end
end

#analyze_action(action, triggered_at_opening, level = 0) ⇒ Object 



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# File 'lib/pdf_scanner/scanner.rb', line 272

def analyze_action(action, triggered_at_opening, level = 0)
  if action.is_a?(Origami::Dictionary)
    type = action[:S].is_a?(Origami::Reference) ? action[:S].solve : action[:S]

    case type.value
    when :JavaScript
      check_rights(:allowJS)
      check_rights(:allowJSAtOpening) if triggered_at_opening
    when :Launch
      check_rights(:allowLaunchAction)
    when :Named
      check_rights(:allowNamedAction)
    when :GoTo
      check_rights(:allowGoToAction)
      dest = action[:D].is_a?(Origami::Reference) ? action[:D].solve : action[:D]
      if dest.is_a?(Origami::Array) and dest.length > 0 and dest.first.is_a?(Origami::Reference)
        dest_page = dest.first.solve
        if dest_page.is_a?(Origami::Page)
          analyze_page(dest_page, level + 1)
        end
      end
    when :GoToE
      check_rights(:allowAttachments,:allowGoToEAction)
    when :GoToR
      check_rights(:allowGoToRAction)
    when :Thread
      check_rights(:allowGoToRAction) if action.key?(:F)
    when :URI
      check_rights(:allowURIAction)
    when :SubmitForm
      check_rights(:allowAcroForms,:allowSubmitFormAction)
    when :ImportData
      check_rights(:allowAcroForms,:allowImportDataAction)
    when :Rendition
      check_rights(:allowScreenAnnotation,:allowRenditionAction)
    when :Sound
      check_rights(:allowSoundAnnotation,:allowSoundAction)
    when :Movie
      check_rights(:allowMovieAnnotation,:allowMovieAction)
    when :RichMediaExecute
      check_rights(:allowRichMediaAnnotation,:allowRichMediaAction)
    when :GoTo3DView
      check_rights(:allow3DAnnotation,:allowGoTo3DAction)
    end

    if action.key?(:Next)
      check_rights(:allowChainedActions)
      analyze_action(action.Next)
    end

  elsif action.is_a?(Origami::Array)
    dest = action
    if dest.length > 0 and dest.first.is_a?(Origami::Reference)
      dest_page = dest.first.solve
      if dest_page.is_a?(Origami::Page)
        check_rights(:allowGoToAction)
        analyze_page(dest_page, level + 1)
      end
    end
  end
end

#analyze_annotation(annot, _level = 0) ⇒ Object 



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# File 'lib/pdf_scanner/scanner.rb', line 214

def analyze_annotation(annot, _level = 0)
  check_rights(:allowAnnotations)

  if annot.is_a?(Origami::Dictionary) and annot.key?(:Subtype)
    check_annotation_rights(annot)

    analyze_3d_annotation(annot) if annot.Subtype.value == :"3D"
  end
end

#analyze_page(page, level = 0) ⇒ Object 



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# File 'lib/pdf_scanner/scanner.rb', line 249

def analyze_page(page, level = 0)
  if page.is_a?(Origami::Dictionary)
    #
    # Checking page additional actions.
    #
    if page.key?(:AA)
      if page.AA.is_a?(Origami::Dictionary)

        aa = Origami::Page::AdditionalActions.new(page.AA); aa.parent = page.AA.parent
        analyze_action(aa.O, true, level + 1) if aa.key?(:O)
        analyze_action(aa.C, false, level + 1) if aa.key?(:C)
      end
    end

    #
    # Looking for page annotations.
    #
    page.each_annotation do |annot|
      analyze_annotation(annot, level + 1)
    end
  end
end

#analyze_xfa_forms(xfa) ⇒ Object 



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# File 'lib/pdf_scanner/scanner.rb', line 179

def analyze_xfa_forms(xfa)
  case xfa
  when Origami::Array then
    xml = ""
    i = 0
    xfa.each do |packet|
      if i % 2 == 1
        xml << packet.solve.data
      end

      i = i + 1
    end
  when Origami::Stream then
      xml = xfa.data
  else
      reject("Malformed XFA dictionary")
  end

  xfadoc = REXML::Document.new(xml)
  REXML::XPath.match(xfadoc, "//script").each do |script|
    case script.attributes["contentType"]
    when "application/x-formcalc" then
      check_rights(:allowFormCalc)
    else
      check_rights(:allowJS)
    end
  end
end

#check_annotation_rights(annot) ⇒ Object 



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# File 'lib/pdf_scanner/scanner.rb', line 208

def check_annotation_rights(annot)
  subtype = annot.Subtype.value

  check_rights(*ANNOTATION_RIGHTS[subtype]) if ANNOTATION_RIGHTS.include?(subtype)
end

#check_rights(*required_rights) ⇒ Object 



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# File 'lib/pdf_scanner/scanner.rb', line 173

def check_rights(*required_rights)
  current_rights = SECURITY_POLICIES["POLICY_#{@options[:policy].upcase}"]

  reject(required_rights) if required_rights.any?{|right| current_rights[right.to_s] == false}
end

#load_config_file(path) ⇒ Object 



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# File 'lib/pdf_scanner/scanner.rb', line 148

def load_config_file(path)
  SECURITY_POLICIES.update(Hash.new(false).update YAML.load(File.read(path)))
end

#quarantine(file, quarantine_folder) ⇒ Object 



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# File 'lib/pdf_scanner/scanner.rb', line 164

def quarantine(file, quarantine_folder)
  digest = Digest::SHA256.file(file)
  ext = File.extname(file)
  dest_name = "#{File.basename(file, ext)}_#{digest}#{ext}"
  dest_path = File.join(quarantine_folder, dest_name)

  FileUtils.move(file, dest_path)
end

#reject(cause, exception_message = nil) ⇒ Object 



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# File 'lib/pdf_scanner/scanner.rb', line 152

def reject(cause, exception_message = nil)
  if @options.key?(:move_dir)
    quarantine(@options[:target_file], @options[:move_dir])
  end

  if exception_message.nil?
    @errors[:rejected_policies] << { policy: @options[:policy], message: cause.inspect }
  else
    @errors[:analysis_failure] << { error: exception_message.to_s, message: cause.inspect }
  end
end

#scan ⇒ Object 



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# File 'lib/pdf_scanner/scanner.rb', line 34

def scan
  begin
    @errors = { rejected_policies: [], analysis_failure: [] }
    if !@options.key?(:policy)
      @options[:policy] = DEFAULT_POLICY
    end

    if @options.key?(:move_dir) and !File.directory?(@options[:move_dir])
      abort "Error: #{@options[:move_dir]} is not a valid directory."
    end

    load_config_file(@options[:config_file] || DEFAULT_CONFIG_FILE)

    unless SECURITY_POLICIES.key?("POLICY_#{@options[:policy].upcase}")
      return "Undeclared policy `#{@options[:policy]}'"
    end

    @pdf = Origami::PDF.read(@options[:target_file],
      verbosity: Origami::Parser::VERBOSE_QUIET,
      ignore_errors: SECURITY_POLICIES["POLICY_#{@options[:policy].upcase}"]['allowParserErrors'],
      decrypt: SECURITY_POLICIES["POLICY_#{@options[:policy].upcase}"]['allowEncryption'],
      prompt_password: lambda { '' },
      password: @options[:password]
    )

    if @pdf.encrypted?
      check_rights(:allowEncryption)
    end

    catalog = @pdf.Catalog
    reject("Invalid document catalog") unless catalog.is_a?(Origami::Catalog)

    if catalog.key?(:OpenAction)
      check_rights(:allowOpenAction)
      action = catalog.OpenAction
      analyze_action(action, true, 1)
    end

    if catalog.key?(:AA)
      if catalog.AA.is_a?(Origami::Dictionary)
        aa = Origami::CatalogAdditionalActions.new(catalog.AA); aa.parent = catalog;
        analyze_action(aa.WC, false, 1) if aa.key?(:WC)
        analyze_action(aa.WS, false, 1) if aa.key?(:WS)
        analyze_action(aa.DS, false, 1) if aa.key?(:DS)
        analyze_action(aa.WP, false, 1) if aa.key?(:WP)
        analyze_action(aa.DP, false, 1) if aa.key?(:DP)
      end
    end

    if catalog.key?(:AcroForm)
      acroform = catalog.AcroForm
      if acroform.is_a?(Origami::Dictionary)
        check_rights(:allowAcroForms)
        if acroform.key?(:XFA)
          check_rights(:allowXFAForms)

          analyze_xfa_forms(acroform[:XFA].solve)
        end
      end
    end

    if @pdf.each_named_script.any?
      check_rights(:allowJS)
      check_rights(:allowJSAtOpening)
    end

    if @pdf.each_attachment.any?
      check_rights(:allowAttachments)
    end

    @pdf.each_page do |page|
      analyze_page(page, 1)
    end

    @pdf.each_object.select{|obj| obj.is_a?(Origami::Stream)}.each do |stream|
      if stream.dictionary.key?(:Filter)
        filters = stream.Filter
        filters = [ filters ] if filters.is_a?(Origami::Name)

        if filters.is_a?(Origami::Array)
          filters.each do |filter|
            case filter.value
            when :ASCIIHexDecode
              check_rights(:allowASCIIHexFilter)
            when :ASCII85Decode
              check_rights(:allowASCII85Filter)
            when :LZWDecode
              check_rights(:allowLZWFilter)
            when :FlateDecode
              check_rights(:allowFlateDecode)
            when :RunLengthDecode
              check_rights(:allowRunLengthFilter)
            when :CCITTFaxDecode
              check_rights(:allowCCITTFaxFilter)
            when :JBIG2Decode
              check_rights(:allowJBIG2Filter)
            when :DCTDecode
              check_rights(:allowDCTFilter)
            when :JPXDecode
              check_rights(:allowJPXFilter)
            when :Crypt
              check_rights(:allowCryptFilter)
            end
          end
        end
      end
    end
  rescue StandardError => ex
    reject("Analysis failure", ex)
  end

  @errors
end