Indicators of Compromise

Overview

An indicator of compromise (IOC) is a piece of information that can be used to help identify the following threats:

• Malware

• An attack

• Other potentially malicious activity

IOCs (once obtained from a reputable source) can be added to a continuous monitoring solution like an SIEM. If there are any matches of IOCs against actual events observed on endpoints or the network, an alert can be generated.

Caution when relying on IOCs

Not all IOCs are created equal. Therefore, some caution needs to be followed when using IOCs from intel feeds. For example, harmless IP addresses and domains can occasionally get swept up in the information collected from a previous security event. Suppose a security incident involved a Google IP address because the attack started when someone searched for something on Google. The search results included a link to malware because of a search engine optimization (SEO) attack. If all IOCs were automatically added to a monitoring solution without prior review, legitimate sites like Google could start triggering alerts, quickly overwhelming the security staff with false positives. Therefore, take all IOCs with a grain of salt, and subject them to a quality control check before use.