Strelka

From https://github.com/target/strelka:

Strelka is a real-time file scanning system used for threat hunting, threat detection, and incident response. Based on the design established by Lockheed Martin’s Laika BOSS and similar projects (see: related projects), Strelka’s purpose is to perform file extraction and metadata collection at huge scale.

Depending on what options you choose in Setup, it may ask if you want to use Zeek or Suricata for metadata. Whichever engine you choose for metadata will then extract files from network traffic. Strelka then analyzes those files and they end up in /nsm/strelka/processed/.

Security Onion checks file hashes before sending to Strelka to avoid analyzing the same file multiple times in a 48 hour period.

Alerts

Strelka scans files using YARA rules. If it detects a match, then it will generate an alert that can be found in Alerts, Dashboards, Hunt, or Kibana. Here is an example of Strelka detecting Poison Ivy RAT:

Drilling into that alert, we find more information about the file and the YARA rule:

You can read more about YARA rules in the Adding Local Rules section.

Logs

Even if Strelka doesn’t detect a YARA match, it will still log metadata about the file. You can find Strelka logs in Dashboards, Hunt, and Kibana. Here’s an example of the default Strelka dashboard in Dashboards:

Configuration

Strelka reads its configuration from /opt/so/conf/strelka/. However, please keep in mind that if you make any changes to this directory they may be overwritten since the configuration is managed with Salt.

Diagnostic Logging

Strelka diagnostic logs are in /nsm/strelka/log/. Depending on what you’re looking for, you may also need to look at the Docker logs for the containers:

sudo docker logs so-strelka-backend
sudo docker logs so-strelka-coordinator
sudo docker logs so-strelka-filestream
sudo docker logs so-strelka-frontend
sudo docker logs so-strelka-manager

More Information

Note

For more information about Strelka, please see https://github.com/target/strelka.