What is Indicators of Compromise IoC?

Understanding Indicators of Compromise IoC

Indicators of Compromise (IoCs) serve as the fingerprints of cyber attacks—specific, observable artifacts that suggest malicious activity has occurred or is occurring in your environment. These technical breadcrumbs include file hashes of malware, IP addresses of command and control servers, domain names used in phishing campaigns, registry keys modified by attackers, or unusual patterns in system logs. Unlike more abstract threat intelligence, IoCs are directly actionable—they can be immediately implemented in security controls as detection or blocking rules. Organizations typically collect IoCs from multiple sources: internal security monitoring, threat intelligence providers, information sharing communities, and public repositories of known indicators. Effective use requires understanding indicator context and confidence levels—knowing which indicators represent definitive evidence of compromise versus those that might generate false positives. IoC management presents challenges around lifecycle (indicators become obsolete as attackers change infrastructure), volume (processing thousands of indicators efficiently), and relevance (determining which indicators matter for your specific environment). Advanced security programs increasingly complement IoCs with behavioral detection to identify attacks that don't match known indicators.