In previous article of the sereies, Enriching Telemetry Events, we walked through how to enrich a domain element of a given telemetry event with WhoIs data like home country, company associated with domain, etc. In this article, we will enrich with a special type of data called threat intel feeds. When a given telemetry event matches data in a threat Intel feed, an alert is generated.

Again, the customers requirement are the following:

1. The proxy events from Squid logs needs to ingested in real-time.
2. The proxy logs has to be parsed into a standardized JSON structure that Metron can understand.
3. In real-time, the squid proxy event needs to be enriched so that the domain named are enriched with the IP information
4. In real-time, the IP with in the proxy event must be checked against for threat intel feeds.
5. If there is a threat intel hit, an alert needs to be raised.
6. The end user must be able to see the new telemetry events and the alerts from the new data source.
7. All of this requirements will need to be implemented easily without writing any new java code.

In this article, we will walk you through how to do 4 and 5.

Threat Intel Framework Explained

Metron currently provides an extensible framework to plug in threat intel sources. Each threat intel source has two components: an enrichment data source and and enrichment bolt. The threat intelligence feeds are bulk loaded and streamed into a threat intelligence store similarly to how the enrichment feeds are loaded. The keys are loaded in a key-value format. The key is the indicator and the value is the JSON formatted description of what the indicator is. It is recommended to use a threat feed aggregator such as Soltra to dedup and normalize the feeds via Stix/Taxii. Metron provides an adapter that is able to read Soltra-produced Stix/Taxii feeds and stream them into Hbase, which is the data store of choice to back high speed threat intel lookups of Metron. Metron additionally provides a flat file and Stix bulk loader that can normalize, dedup, and bulk load or stream threat intel data into Hbase even without the use of a threat feed aggregator.

The below diagram illustrates the architecture:

Step 1: Setup and Pre-requisites

1. You should have completed the instructions in Adding a new Telemetry Data Source

2. Make sure the following variables are configured based on your environment: 

   
   KAFKA_HOST = host where a Kafka broker is installed
   ZOOKEEPER_HOST = host where a Zookeeper server is installed
   PROBE_HOST = Host where your sensor, probes are installed. If don't have any sensors installed, pick the host where a storm supervisor is running
   SQUID_HOST = Host where you want to install SQUID. If you don't care, just install on the PROBE_HOST
   NIFI_HOST = The host where you will install NIFI. You want this this to be same host that you installed Squid.
   HOST_WITH_ENRICHMENT_TAG = This is the host in your inventory hosts file that you put under the group "enrichment" 
   SEARCH_HOST = This is the host where you have elastic or solr running. This is the host in your inventory hosts file that you put under the group "search". Pick one of the search hosts
   SEARCH_HOST_PORT = The port of the search host where indexing is configured. (e.g: 9300)
   METRON_UI_HOST = This is the host where your metron ui web application is running. This is the host in your inventory hosts file that you put under the group "web".
   METRON_VERSION = The release of the metron binaries you are working with (e.g: 0.2.0BETA-RC2)

Step 2: Create a Mock Threat Intel Feed Source

Metron is designed to work with Stix/Taxii threat feeds, but can also be bulk loaded with threat data from a CSV file. In this example we will explore the CSV example. The same loader framework that is used for enrichment here is used for threat intelligence. Similarly to enrichments we need to setup a data.csv file, the extractor config JSON and the enrichment config JSON.

For this example we will be using a Zeus malware tracker list located here: https://zeustracker.abuse.ch/blocklist.php?download=domainblocklist.

1. Log into the $HOST_WITH_ENRICHMENT_TAG as root
2. Lets copy the contents from that link to a file called domainblocklist.csv 

   
   curl https://zeustracker.abuse.ch/blocklist.php?download=domainblocklist | grep -v "^#" | grep -v "^$" | grep -v "^https" | awk '{print $1",abuse.ch"}' > domainblocklist.csv

Step 3: Configure an Extractor Config File

1. Log into the $HOST_WITH_ENRICHMENT_TAG as root
2. Now that we have the "Threat Intel Feed Source" , we need to now configure an extractor config file that describes the the source. Create a file called extractor_config_temp.json and put the following contents in it. 

   
   {
   "config" : {
       "columns" : {
           "domain" : 0
           ,"source" : 1
       }
       ,"indicator_column" : "domain"
       ,"type" : "zeusList"
       ,"separator" : ","
     }
     ,"extractor" : "CSV"
   }

    

3. Run the following to remove the non-ascii characters we run the following:

   1. iconv -c -f utf-8 -t ascii extractor_config_temp.json -o extractor_config.json

Step 4: Configure Element to Threat Intel Feed Mapping

We now have to configure what element of a tuple and what threat intel feed to cross-reference with.This configuration will be stored in zookeeper.

1. Log into the $HOST_WITH_ENRICHMENT_TAG as root
2. Cut and paste this file into a file called "enrichment_config_temp.json" .  

   
   {
        "zkQuorum" : "$ZOOKEEPER_HOST:2181"
       ,"sensorToFieldList" : {
        "squid" : {
             "type" : "THREAT_INTEL"
            ,"fieldToEnrichmentTypes" : {
                  "domain_without_subdomains" : [ "zeusList" ]
             }
        }
      }
   }

    

3. Because copying and pasting from this blog will include some non-ascii invisible characters, to strip them out please run

   iconv -c -f utf-8 -t ascii enrichment_config_temp.json -o enrichment_config.json

Step 5: Run the Threat Intel Loader

Now that we have the threat intel source,  threat intel exractor and threat intel mapping config defined, we can now run the loader to move the data from the threat intel source to the Metron threat intel Store and store the enrichment config in zookeeper.

1. Log into the $HOST_WITH_ENRICHMENT_TAG as root
2. Run the loader

        /usr/metron/$METRON_RELEASE/bin/flatfile_loader.sh -n enrichment_config.json -i domainblocklist.csv -t threatintel -c t -e extractor_config.json

3. After this, the threat intel data will be loaded in Hbase and a Zookeeper mapping will be established. The data will be populated into Hbase table called threatintel. To verify that the logs were properly ingested into Hbase run the following command: 

       hbase shell
       scan 'threatintel'

4. Now check if Zookeeper enrichment tag was properly populated:  

      /usr/metron/$METRON_RELEASE/bin/zk_load_configs.sh -m DUMP -z $ZOOKEEPER_HOST:2181

5. You should see a config for the squid sensor something like the following: 
   1. 
6. Generate some data by using the squid client to execute http requests (do this about 20 times)

       squidclient http://www.actdhaka.com

Step 6: View the Threat Alerts in Metron UI

Now that we have configured real-time threat intel cross referencing so that alerts get generated when there is a hit for the squid sensor, lets render these alerts on the Metron UI. We will be adding 32new panels to visualize the Squid Alerts:  Creating a Threat Intel Hits Count Pane and Alert Detail Panel.

Creating a Threat Intel Hits Count Panel 

1. Log into the Metron UI Dashboard: http://METRON_UI_HOST:5000
2. Select "Visualize" Tab --> Select "Metric" Visualization"= --> Select "From a new search" for Search Source --> Select "squid*" index source
3. In the search box, enter "is_alert =  true" and execute search
4.  Click the Save disk icon on the top right and name  the Visualization "Threat Intel Hits" and click Save
5. Select "Dashboard" Tab --> Click the plus icon --> Select "Visualization" tab --> Search for "Squid Event Count" --> Select it
6. The visualization will be added to the bottom of the dashboard
7. Click the save icon on the top right to save the dashboard.

Creating an Alert Detail Panel 

1. Log into the Metron UI Dashboard: http://METRON_UI_HOST:5000
2. Select "Discover" Tab --> Select the "squid*" index
3. Search only for alerts in the squid index
   1. Type the following in search "is_alert = true" 
   2. click the search icon
4. Now we only to select subset of the fields that we want to display in the detail panel. In the left hand panel under "Available Fields", "add" the following fields:
   1. full_hostname
   2. ip_src_addr
   3. ip_dst_addr
   4. original_string
   5. method
   6. type

Dashboard with the 2 Panels

The following is what the new dashboard would look like with those 2 panels.