Crowdsourced TI aggregates intelligence from many contributors — VirusTotal (file/URL reputation), AlienVault OTX (IoC sharing), ISACs (sector-specific), MISP (open-source sharing platform).
ISACs (Information Sharing and Analysis Centers) provide sector-specific TI — FS-ISAC (financial), H-ISAC (healthcare), E-ISAC (electricity). Sharing TI benefits all participants. Automated STIX/TAXII ingestion makes TI actionable in SIEM/SOAR.