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Rapid7 Threat CommandIndicators of compromise (IOCs) are pieces of contextual information discovered in forensic analysis that serve to alert analysts of past/ongoing attacks, network breaches, or malware infections. These unique clues – or artifacts – are often seen as maliciously used IP addresses, URLs, domains, or hashes. It certainly helps to be alerted to an IOC so that you know something has potentially gone wrong, but very often IOCs lack context that can empower a security operations center (SOC) to prioritize and act quickly to secure a breach.
Although use of the acronym IOC is widespread in the cybersecurity community, the phrase “indicator of compromise” generally means any type of threat intelligence that could indicate something out of the ordinary. In addition to those mentioned above, scenarios typically identified by an IOC include changes in network traffic, ransomware attacks, or identity and access management (IAM) anomalies.
When systems signal themselves with activity that lies outside of the normal baseline range, contextual information can help teams to define the type of potential attack and refine security operations like anti-malware procedures and devices, alter SIEM configuration, and conduct more thorough and efficient investigations.
In fact, according to Forrester, many cybersecurity vendors are now disseminating IOC security intelligence feeds into many enterprise functions. This helps to natively spot IOCs within a security tool as opposed to using a separate IOC feed.
The process for identifying IOCs is a process of poring through analytics and threat intelligence to identify anomalous behaviors that could be nefarious – or could be nothing at all. Again, analysts and investigators will need to rely heavily on context to make significant headway.
That said, not all processes to identify early indicators of a pending compromise will be the same or even similar. They’ll be business and use-case specific. Let’s take a look at some more common IOC identification methods:
Since IOCs are essentially clues that can – after some digital forensics work – point to something nefarious, they can come in many shapes and sizes. Let's take a look at some examples of IOCs that can and should set off alarm bells:
There are several overlapping concepts between IOCs and indicators of attack (IOAs). However, it helps to zoom in on key differences to understand why analysts would define an issue as either an IOC or IOA.
We've spoken about artifacts previously, but it may help to add some context. Artifacts are usually historical in nature. They are digital footprints of a malicious event that has already occurred, and are found by performing threat hunts based on specific intelligence. Security analysts and threat hunters can also leverage outside artifact libraries to familiarize themselves with what to look for on their own networks.
After artifacts are found and determined to indicate a potential breach or ongoing threat, teams can put an incident response plan into action. The faster security practitioners can learn that a compromise has actually taken place, the faster they can determine what happened, respond, and – hopefully – have a better idea of the kinds of artifacts to look for in the future.
IOAs help keep attacks out of your organization’s history. They are signs that an attack could be imminent. With IOAs, teams are able to take more of an offensive stance, acting on extended detection and response (XDR) threat telemetry that goes beyond the network perimeter as attack surfaces stretch even further.
Interpreted correctly, IOAs will not only help teams respond to future or in-progress breaches, they can also help predict what an attacker might do and where they might go next. This can be incredibly helpful in prioritizing response and remediation efforts based on the systems being targeted and data attempting to be accessed and/or exfiltrated.
The benefits of IOCs are many. Primary among them is they can help companies remediate breaches and perhaps provide context on the types of attacker behavior to look for in the future. Let's take a look at a few others:
IOCs are important for an effective managed detection and response (MDR) program because it’s critical for an MDR provider to be able to identify IOCs across their entire customer ecosystem.
This helps the provider to spot trends in attacker behavior, build out net detections as IOCs are found, tailor incident response plans, and disseminate that information to their customer base so that those individual security organizations can implement IOC data into their own prevention technologies.
It’s also important for MDR programs to consider the efficiency gains and cost savings that can come with leveraging IOCs to inform breach response. Customer satisfaction is also a growth driver, particularly after successful implementation of an MDR provider-recommended plan or after a provider has automatically tested IOCs and applied them to customer logs to create alerts when those indicators pop up in their networks.
All of these aspects combine to help MDR providers retain customers, improve their own operations, as well as strengthen the larger security community by sharing findings.