Indicators of compromise (IoCs) refer to forensic data like that found in system or file logs that indicate potentially malicious activity on a system or network. They help information security and IT professionals detect data breaches, malware infections, or the presence of threats.

Monitoring for IoCs lets organizations detect attacks and act quickly to prevent breaches or limit the damage by thwarting attacks as soon as possible.

Other interesting terms…

Read More about “Indicators of Compromise (IoCs)”

There are various types of IoCs. We named and described several below.

What Are the Types of Indicators of Compromise?

Security analysts and researchers collate and use IoCs to boost their network and system security. They feed the data into cybersecurity applications so they would monitor for the IoCs’ presence and prevent computers from accessing them.

The most common IoCs are:

  • Unusual outbound network traffic: The traffic that leaves a network could indicate potential issues. Suspicious and unusual amounts of outbound traffic should prompt the IT team to check if anything is amiss. The traffic may be caused by unauthorized data exfiltration.
  • Geographical irregularities: Even the most prominent enterprises don’t have employees in every country. That said, login attempts from countries where your organization doesn’t typically do business could signify a potential security compromise.
  • Database read volume swells: Data exfiltration typically leads to swells in the read volume. That’s why it’s essential to track unusual spikes in network traffic.
  • Large request number for the same file: It’s pretty normal, isn’t it, to keep trying to exfiltrate the file you’re targeting until you succeed. As such, a file that’s repeatedly downloaded could indicate numerous theft attempts.
  • Suspicious registry or system file changes: Several malware often change registry or system files. Any questionable change may be an IoC.
  • Privileged user account activity anomalies: Privileged user accounts have access to sensitive files. As such, abnormalities can help IT teams identify attacks early on before they can do significant damage. Users trying to escalate the privileges of particular accounts are thus suspect.
  • Login red flags: It’s normal for users to take note of their login credentials. So, users trying to log in numerous times could be bad actors attempting to break into the network.
  • HTML response sizes: If your network’s typical HyperText Markup Language (HTML) response size is small, but you notice far larger response sizes, attackers may have exfiltrated your data.
  • Mismatched port-application traffic: Threat actors often exploit ports to instigate attacks. Unusual ports could indicate attempts to compromise the network.
  • DNS request anomalies: Hackers often use command-and-control (C&C) servers to compromise networks. Anomalous Domain Name System (DNS) requests can be IoCs, especially those from countries where the organization doesn’t have legitimate users.

Are Indicators of Compromise the Same as Indicators of Attack?

Indicators of attack and IoCs are similar. But indicators of attack focus on identifying activities while attacks are in progress. While IoCs answer the question, “What happened?”; indicators of attack answer the question, “What is happening and why?”

What Are the Uses of Indicators of Compromise?

Monitoring for IoCs allows organizations to detect and respond to security compromises better. Collecting and correlating IoCs in real-time lets users identify security incidents that may have gone undetected by tools and provides the resources needed to perform forensic analysis. Recurring IoC patterns should also push infosec teams to update their cybersecurity tools and policies to protect against future attacks.

Reporting IoCs can also help other companies and security professionals to automate detecting, preventing, and reporting security incidents. IoCs are critical to battling malware and other cyber attacks. While they may be reactive, organizations that monitor for IoCs diligently can still improve their detection rates and response times significantly.

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Learning to detect IoCs is crucial to comprehensive cybersecurity strategies. They can help improve detection accuracy and speed and hasten remediation times. The faster an organization detects an attack, the less damage it can have on the business and the easier it is to resolve.

IoCs, especially recurring ones, also give organizations insights into threat actors’ tools, tactics, and procedures (TTPs). Incorporating these insights into security tools enhances incident response capabilities and cybersecurity policies to prevent future incidents.