Question 420
A risk review at a distributed branch estate focuses on preventing this issue again: An HTTPS EDL remains stale after the feed host rotates its certificate and the firewall cannot validate the new server identity. Which recurring control is most suitable?
Explanation
Correct Answer
Alert on certificate-expiry windows for externally hosted feed endpoints. This control reduces recurrence of the documented mechanism: Secure EDL retrieval depends on a valid and trusted HTTPS server connection. It creates a repeatable check around the needed response: Update the approved certificate profile or restore the feed server's trusted chain for HTTPS retrieval.
Incorrect Answers
Lint each feed as its declared list type before deployment. That safeguard addresses another potential failure: A URL EDL uses IP/CIDR entries so the firewall ignores the values when applying a URL Filtering policy. It is not the most targeted recurring control for the described cause: Secure EDL retrieval depends on a valid and trusted HTTPS server connection.
Document refresh cadence and operational verification for urgent indicator updates. That safeguard addresses another potential failure: An administrator modifies an EDL text file but immediately commits firewall configuration expecting that commit itself to fetch the new indicators. It is not the most targeted recurring control for the described cause: Secure EDL retrieval depends on a valid and trusted HTTPS server connection.
Validate threat-feed schema and entry types before publishing updates. That safeguard addresses another potential failure: An SOC provides an external IP threat feed containing URL strings and domain names inside a file configured as an IP external dynamic list. It is not the most targeted recurring control for the described cause: Secure EDL retrieval depends on a valid and trusted HTTPS server connection.