Class: LogStash::Filters::Decrypt

Inherits:
Base
  • Object
show all
Defined in:
lib/logstash/filters/decrypt.rb

Instance Method Summary collapse

Instance Method Details

#filter(event) ⇒ Object 



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# File 'lib/logstash/filters/decrypt.rb', line 34

def filter(event)

  if @source
    source = event.get(@source)
    # Replace the event message with our message as configured in the
    # config file.
    parsed = LogStash::Json.load(source)

    parsed_timestamp = parsed.delete(LogStash::Event::TIMESTAMP)
    begin
      timestamp = parsed_timestamp ? LogStash::Timestamp.coerce(parsed_timestamp) : nil
    rescue LogStash::TimestampParserError => e
      timestamp = nil
    end

    threads = []

    @campaigns.each do |file|
      file = File.read(file)
      campaign = LogStash::Json.load(file)
      @keywordstrategy = nil
      @strategies = campaign['SearchStrategies']
      @strategies.each do |strategy|
        if strategy["type"].eql? "KeywordStrategy"
          @logger.info("Found Keyword Strategy")
          @keywordstrategy = strategy
        end
      end
      if parsed["body"].nil? || parsed["body"].empty?
        @logger.info("Empty Body -> Skip")
      elsif @keywordstrategy.nil?
        @logger.info("No Keyword Strategy found -> Skip")
      elsif parsed["body"].include? @keywordstrategy["prefix"]
        @logger.info("Decrypt Body")
        threads << Thread.new {

           if campaign["encryption"]["xor"].any?
             xor=Xor.new(@keywordstrategy["prefix"],parsed["body"],campaign["encryption"]["xor"],@keywordstrategy["keywords"])
             result = xor.xordecrypt
             if result[0]
               parsed["decrypted"] = result[1]
               parsed["tags"] = [campaign["name"],"XOR"]
             end
           end

           if campaign["encryption"]["aes"].any?
             aes=Aes.new(@keywordstrategy["prefix"],parsed["body"],campaign["encryption"]["aes"],@keywordstrategy["keywords"])
             result = aes.aesdecrypt
             if result[0]
               parsed["decrypted"] = result[1]
               parsed["tags"] = [campaign["name"],"AES"]
             end
           end
          }
      else
        @logger.info("Prefix not in Payload -> Skip")
      end
    end

    threads.each { |thr| thr.join }

    # using the event.set API
    parsed.each{|k, v| event.set(k, v)}

    if parsed_timestamp
      if timestamp
        event.timestamp = timestamp
      else
        event.timestamp = LogStash::Timestamp.new
        @logger.warn("Unrecognized #{LogStash::Event::TIMESTAMP} value, setting current time to #{LogStash::Event::TIMESTAMP}, original in #{LogStash::Event::TIMESTAMP_FAILURE_FIELD} field", :value => parsed_timestamp.inspect)
        event.tag(LogStash::Event::TIMESTAMP_FAILURE_TAG)
        event.set(LogStash::Event::TIMESTAMP_FAILURE_FIELD, parsed_timestamp.to_s)
      end
    end
    # correct debugging log statement for reference
    # using the event.get API
    @logger.info("Event after filter", :event => event)
  end

  # filter_matched should go in the last line of our successful code
  filter_matched(event)
end

#register ⇒ Object 



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# File 'lib/logstash/filters/decrypt.rb', line 28

def register
  # Add instance variables
  @campaigns = Dir.glob("campaigns/*.json")
end