Hi all,

I am trying to identify a port scan event.

The basic fact is connection log. For each combination of src (source IP) and dst (destination IP) , detect a port scan event, if over 60 seconds there were at least 20 connection logs with different service and protocol.

The event will stay closed for 10 minute - no event will be sent during this time for this combination of  src and dst. The event will contain the connection logs’ ids (markers).

I tried to implement it using “accumulate” and “over window:time” but it consumes too much memory.

So I am trying to imitate this functionality using several rules and facts.

My drl contains the following lines (among others):

declare CorrelatedEvent

        @role( event)

        @expires( 600s )

end

declare CandidatesWindow

        @role( event)

        @expires( 60s )

end

rule "Create Port Scan Event - 1"

enabled true

dialect "java"   

no-loop               

when

     $log : Log()

      not CorrelatedEvent(getId() == "portScan" , groupByFieldsMap.get("src") == $log.fieldsMap.get("src") ,groupByFieldsMap.get("dst") == $log.fieldsMap.get("dst"))

      $windows : ArrayList()

           from collect( CandidatesWindow(getRuleId() == "portScan" , groupByFieldsMap.get("src") == $log.fieldsMap.get("src") , groupByFieldsMap.get("dst") == $log.fieldsMap.get("dst")))

then

  String id = $log.fieldsMap.get("port").toString();

  System.out.println(new Date().toString()+" windowSize: " + $windows.size());

  for (Object windowObj : $windows) {

    CandidatesWindow window = (CandidatesWindow) windowObj;

    modify ( window ) { addLog($log, id) }

  }

  CandidatesWindow newWindow = new CandidatesWindow("portScan", true);

  newWindow.groupByFieldsMap.put("src", $log.fieldsMap.get("src"));

  newWindow.groupByFieldsMap.put("dst", $log.fieldsMap.get("dst"));

  newWindow.addLog($log, id);

  insert(newWindow);

end

This imitates sliding time windows.

when I tested it, I got the following exception:

Exception executing consequence for rule "Create Port Scan Event - 1" in com.checkpoint.correlation.impl.drools.package1: java.util.ConcurrentModificationException

                at org.drools.runtime.rule.impl.DefaultConsequenceExceptionHandler.handleException(DefaultConsequenceExceptionHandler.java:39)

                at org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:1297)

                at org.drools.common.DefaultAgenda.fireNextItem(DefaultAgenda.java:1221)

                at org.drools.common.DefaultAgenda.fireAllRules(DefaultAgenda.java:1456)

                at org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:710)

                at org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:674)

                at org.drools.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:230)

                at com.checkpoint.correlation.impl.drools.DroolsCEPEngineV1.insertEvents(DroolsCEPEngineV1.java:173)

                at com.checkpoint.correlation.impl.feeder.JsonFileFeeder.init(JsonFileFeeder.java:68)

                at com.checkpoint.correlation.server.CorrelationServer.initFeeder(CorrelationServer.java:63)

                at com.checkpoint.correlation.server.CorrelationServer.run(CorrelationServer.java:28)

                at com.checkpoint.correlation.server.CorrelationServer.runServer(CorrelationServer.java:101)

                at com.checkpoint.correlation.server.CorrelationServer.main(CorrelationServer.java:85)

Caused by: java.util.ConcurrentModificationException

                at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:819)

                at java.util.ArrayList$Itr.next(ArrayList.java:791)

                at com.checkpoint.correlation.impl.drools.package1.Rule_Create_Port_Scan_Event___1_2f94bc67f9064c6e9614982cf9bc8859.defaultConsequence(Rule_Create_Port_Scan_Event___1_2f94bc67f9064c6e9614982cf9bc8859.java:11)

                at com.checkpoint.correlation.impl.drools.package1.Rule_Create_Port_Scan_Event___1_2f94bc67f9064c6e9614982cf9bc8859DefaultConsequenceInvokerGenerated.evaluate(Unknown Source)

                at com.checkpoint.correlation.impl.drools.package1.Rule_Create_Port_Scan_Event___1_2f94bc67f9064c6e9614982cf9bc8859DefaultConsequenceInvoker.evaluate(Unknown Source)

                at org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:1287)

                ... 11 more

It is caused by modify ( window ) in the for loop.

How can I make it work?

Thanks.