Using Zeek's new JavaScript support for MISP integration

By Arne Welzel January 3, 2024

Using Zeek’s new JavaScript support for MISP integration

With Zeek 6.0, experimental JavaScript support was added to Zeek, making Node.js and its vast ecosystem available to Zeek script developers to more easily integrate with external systems.

MISP Integration

As a tech-demo, the popular Zeek package dovehawk has been re-implemented using JavaScript. The re-implementation is named zeekjs-misp and has been published on GitHub.

In essence, the new package uses Node’s https module to communicate with MISP’s Rest API, achieving the following:

Demo

One component for the demo is a misp-docker docker-compose setup. The misp-docker project makes it very easy to run a local MISP instance for testing. The default “Tor ALL nodes” feed is enabled in this instance. This feed provides ip-dst attributes for all currently known Tor nodes. zeekjs-misp fetches these and converts the ip-dst attributes into Zeek Intel::ADDR intelligence items.

The other component of the demo is a Zeek container running in host-network mode with the zeekjs-misp package installed. Zeek’s official container images have JavaScript support built-in by default. For demonstration purposes, the individual commands are reproduced below. Usually, the package installation via zkg would be done in a dedicated Dockerfile. The MISP options would conventionally be placed into local.zeek instead of directly on the command line.

First, the container is started and the zeekjs-misp package installed:

$ docker pull zeek/zeek
$ docker run --net=host --rm -it zeek/zeek
# zeek -N Zeek::JavaScript
Zeek::JavaScript - Experimental JavaScript support for Zeek (built-in)
# echo "yes" | zkg install zeekjs-misp
The following packages will be INSTALLED:
  zeek/awelzel/zeekjs-misp (main)

Proceed? [Y/n] Installing "zeek/awelzel/zeekjs-misp"
Installed "zeek/awelzel/zeekjs-misp" (main)
Loaded "zeek/awelzel/zeekjs-misp"

Thereafter, Zeek is invoked as follows. This loads the zeekjs-misp and frameworks/intel/seen packages and uses the wireless interface of the host (available within the container due to running in host networking mode). It further configures the zeekjs-misp authentication options for use with the testing MISP instance and enables debug logging:

# zeek -C -i  wlp0s20f3 zeekjs-misp frameworks/intel/seen  MISP::url=https://localhost MISP::api_key=6gIV…BAJ MISP::insecure=T MISP::debug=T
<params>, line 1: listening on wlp0s20f3

zeek-misp: Starting up zeekjs-misp
zeek-misp: url https://localhost
zeek-misp: api_key 6gIV...
zeek-misp: refresh_interval 120000
zeek-misp: max_item_sightings 5n
zeek-misp: max_item_sightings_interval 5000
zeek-misp: Schedule for 120000...
zeek-misp: Loading intel data through attributes search
zeek-misp: Attribute search {"tags":[],"to_ids":1,"eventid":[],"type":"!yara,!malware-sample,!ssdeep,!pattern-in-traffic,!btc","from":1695133600}
zeek-misp: searchAttributes done items=8660 requestMs=213.13ms insertMs=108.82661300897598ms
zeek-misp: Summary of attribute types
zeek-misp:   ip-dst = 8660
zeek-misp: Attributes search done

The output shows that 8660 ip-dst attributes have been fetched from the MISP instance and inserted into Zeek’s Intelligence store. Attributes are fetched every 2 minutes by default. The package provides further configurability to limit the time range, filter attributes by types, or limit to attributes of specific events only.

There is now a single Zeek process running, monitoring the wireless interface of the host. Running nc on the host system to establish a connection to one of the active Tor node IPs shows Zeek successfully detecting the connection and producing an intel.log entry.

On the host system:

$ nc -z -v 97.107.139.108 80
Connection to 97.107.139.108 80 port [tcp/http] succeeded!

Within the container where Zeek is running, the Intel::match event and sighting report is logged and the intel.log file populated.

<params>, line 1: listening on wlp0s20f3
...
zeek-misp: zeek-misp: Intel::match 97.107.139.108
zeek-misp: Sightings reported 97.107.139.108
^Z

# zeek-cut -m ts uid id.resp_h seen.indicator seen.indicator_type sources < intel.log 
ts      uid     id.resp_h       seen.indicator  seen.indicator_type     sources
1702911422.470607       CXNOS517lUT5M5wBuk      97.107.139.108  97.107.139.108  Intel::ADDR     MISP-1

Navigating to the event in the MISP UI for the Tor All Nodes feed shows an increased number of sightings:

MISP sightings reported by zeekjs-misp

Conclusion

Zeek’s new JavaScript support enables easier integration with external systems. The zeekjs-misp package allows connecting Zeek with a MISP instance using MISP’s extensive REST API. Note that the zeekjs-misp package is currently meant as a tech demo. The author of the package isn’t a MISP user and deploying it in a production environment may come with further requirements.

Feedback and contributions on GitHub are more than welcome. Also, feel free to reach out in the Zeek Slack’s package channel.

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