Reference:
https://www.cisco.com/c/dam/en/us/td/docs/security/ces/overview_guide/Cisco_Cloud_Hybrid_Email_Security_

The process that uses STIX and allows uploads and downloads of block lists is sharing. STIX (Structured Threat Information Expression) is a standard language and format for exchanging cyber threat intelligence data. Block lists are collections of observables, such as IP addresses, URLs, or domains, that are associated with malicious activity and can be used to block or monitor network traffic. Cisco Threat Intelligence Director (TID) is a feature that operationalizes threat intelligence data by consuming, normalizing, publishing, and correlating data from various sources, including third-party STIX feeds. TID enables the administrator to upload STIX files from local or remote sources, or download STIX files from the Firepower Management Center (FMC) to share with other systems. TID also allows the administrator to configure actions (such as block or monitor) based on the indicators and observables in the STIX files, and generate incidents and observations when the system detects traffic that matches the threat intelligence data123 References := 1: Firepower Management Center Configuration Guide, Version 6.2.3 - Threat Intelligence Director 2 2: Introduction to STIX - GitHub Pages 4 3: Third-Party Integration of Security Feeds with FMC (Cisco Threat Intelligence Director) - Cisco Community 3