A question from Customer Success Office Hours: Cortex XDR Exclusions and Exceptions

[rtsedaka]

What are the differences between Exclusions and Exceptions and related best practices? 

Cortex XDR 

[bbucao · Accepted solution]

Alert Exclusion rules hide alerts and excludes them from being included in Incidents, but does NOT change the behavior of the XDR agent in any way. In addition, when you create an alert exclusion policy you have the option to apply the exclusion to historical alerts, if this option is chosen, existing alerts that match the rule conditions will be grayed out in the alerts table. If all alerts contained in an existing Incident are excluded, the Incident will be auto-resolved.

Creating an Exception rule DOES change the behavior of the XDR agent. If you create an alert exception, Cortex XDR will no longer take action or alert on matching traffic.

Example scenario:

You have a Behavioral Threat Prevention alert that was blocked. You determine the associated traffic to be legitimate business related traffic and therefore do not wish to alert on it in the future.

If you were to create an alert exclusion policy to match this traffic, you would not see future matching alerts, and they would not be included in any future Incidents, but the agent would continue to block the matching traffic since only an alert exclusion was configured.
To prevent the XDR agent from blocking this traffic in the future, you would need to create an Exception.

For both Exclusions and Exceptions, best practice is to define your rules as specific as possible in order to best tune out noise without degrading the ability to alert/prevent malicious activity.

Regards,
Ben