What an IOC does
IOCs are essentially digital fingerprints of malicious activity. These can take many forms, including file hashes (unique identifiers for malware), IP addresses or domains used by attackers, registry keys modified by malicious software, and unusual behavioural patterns within a system. Standardised formats like STIX and TAXII facilitate the exchange of IOCs between security tools and organisations, ensuring threat intelligence is shared effectively. The value of an IOC diminishes as time passes; a 'fresh' IOC is actionable, while a 'stale' IOC is unlikely to represent a current threat.
IOCs in Australian tenants today
For AU mid-market organisations, effectively managing IOCs is increasingly important, particularly given the ACSC Essential Eight guidance on threat detection and response. Microsoft Defender XDR allows for the creation of custom indicators, enabling tailored threat detection. Microsoft Sentinel’s threat intelligence connectors enable the ingestion of IOC feeds from various sources, including potentially ACSC’s threat intelligence sharing platform. Organisations must establish processes to regularly review and update their IOCs to maintain their relevance and effectiveness, aligning with APRA CPS 234’s focus on operational resilience.