Snaring the Bad Folks. Project by Netflix’s Cloud… | by Netflix Technology Blog | Dec, 2021

Snaring the Bad Folks. Project by Netflix’s Cloud… | by Netflix Technology Blog | Dec, 2021


Snare was built from the ground up to be scalable to manage Netflix’s massive scale. We currently process tens of millions of log records every minute and analyze these events to perform in-house custom detections. We collect findings from a number of sources, which includes AWS Security Hub, AWS Config Rules, and our own in-house custom detections. Once ingested, findings are then enriched and processed with additional metadata collected from Netflix’s internal data sources. Finally, findings are checked against suppression rules and routed to our control plane for triaging and remediation.

We’ve developed, deployed, and operated Snare for almost a year, and since then, we’ve seen tremendous improvements while handling our cloud security findings. A number of findings are auto remediated, others utilize slack alerts to loop in the oncall to triage via the Snare UI. One major improvement was a direct time savings for our detection squad. Utilizing Snare, we were able to perform more granular tuning and aggregation of findings leading to an average of 73.5% reduction in our false positive finding volume across our ingestion streams. With this additional time, we were able to focus on new detections and new features for Snare.

Speaking of new detections, we’ve more than doubled the number of our in-house detections, and onboarded several detection solutions from security vendors. The Snare framework enables us to write detections quickly and efficiently with all of the plumbing and configurations abstracted away from us. Detection authors only need to be concerned with their actual detection logic, and everything else is handled for them.

As for security vendors, we’ve most notably worked with AWS to ensure that services like GuardDuty and Security Hub are first class citizens when it comes to detection sources. Integration with Security Hub was a critical design decision from the start due to the high amount of leverage we get from receiving all of the AWS Security findings in a normalized format and in a centralized location. Security Hub has played an integral role in our platform, and made evaluations of AWS security services and new features easy to try out and adopt. Our plumbing between Security Hub and Snare is managed through AWS Organizations as well as EventBridge rules deployed in every region and account to aid in aggregating all findings into our centralized Snare platform.

One area that we are investing heavily is our automated remediation potential. We’ve explored a few different options ranging from fully automated remediations, manually triggered remediations, as well as automated playbooks for additional data gathering during incident triage. We decided to employ AWS Step Functions to be our execution environment due to the unique DAGs we could build and the simplistic “wait”/”task token” functionality, which allows us to involve humans when necessary for approval/input.

Building on top of step functions, we created a 4 step remediation process: pre-processing, decision, remediation, and post-processing. Pre/post processing can be used for managing out-of-band resource checks, or any work that needs to be done in order to ensure a successful remediation. The decision step is used to perform a final pre-flight check before remediation. This can involve a human reachout, verifying the resource is still around, etc. The remediation step is where we perform our actual remediation. We’ve been able to use this to a great deal of success with infrastructure-wide misconfigured resources being automatically fixed near real time, and enabling the creation of new fully automated incident response playbooks. We’re still exploring new ways we might be able to use this, and are excited for how we might evolve our approach in the near future.

Diagram from a remediation to enable S3’s public access block on a non-compliant bucket. Each choice stage allows for dynamic routing to a variety of different stages based on the output of the previous function. Wait stages are used when human intervention/approval is needed.



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