10 Indicators of Compromise (IOC) Examples To Look Out For

indicators of compromise

As information security professionals, you play a crucial role in using the term “indicators of compromise” (IOC) to describe any malicious activity that may suggest a computer system has been compromised. Your expertise in identifying IoCs can help quickly determine when an attack has occurred and identify the perpetrators. Your insights can also help determine the extent and severity of an attack and aid in an incident’s forensic analysis.

This guide is not just a theoretical exploration of the top 10 indicators of compromise. It’s a practical tool that can empower your security team to develop effective incident response plans and safeguard your valuable data and assets. By understanding and monitoring these warning signs, you can stay one step ahead of potential threats.

How to Recognize 10 Common Indicators of Compromise

There is a wide range of IoCs to look out for, but they all have the same goal: to warn you that your system has been compromised. The sooner you can identify a compromise, the less damage the attacker can do.

Here are just a few examples of what to look for:

Anomalous Outbound Traffic on the Network

One standard indicator of a compromised system is outbound traffic that is not typically seen on the system.

This could include traffic to unfamiliar or suspicious IP addresses, known malicious websites, or sudden spikes and dips in network traffic. Monitoring for unusual network traffic patterns is crucial for detecting potential security incidents.

Unusual User Account Activity

Unusual activity and unexpected changes in user behavior, such as accessing files or systems they don’t usually need, logging in at unusual times, or making privilege escalation requests, can signal that an account has been compromised.

Monitoring user activities and access patterns is essential for identifying potential insider threats or compromised accounts.

Access Attempts from Outside Geographical Area

If you notice login attempts or suspicious activity originating from unfamiliar locations, it could indicate that an unauthorized user is trying to gain access to your systems. 

Tracking geolocation data, unauthorized access attempts, and analyzing login patterns can help detect these anomalies.

Migration and Aggregation of Files

Observing a sudden influx of files being moved or copied to unusual locations, especially sensitive or critical data, may suggest an attacker is trying to exfiltrate information (i.e. data exfiltration). Implementing file monitoring and data loss prevention (DLP) tools can help identify these suspicious activities.

Influx of Spam Emails

A sudden increase in suspicious, unsolicited emails employees receive could signify a phishing campaign targeting your organization. Integrating email security solutions and training employees to recognize phishing attempts can mitigate this risk.

Unusual Application Activity

Detecting the installation or execution of unfamiliar applications, especially those running with elevated privileges, may signify the presence of malware or unauthorized software.

Leveraging endpoint security solutions and application monitoring can help identify and block these suspicious activities.

DDoS Attack

A distributed denial-of-service (DDoS) attack is a critical threat and can overwhelm your systems, making them unresponsive or unavailable.

This disruption of normal operations is a clear indicator of compromise. Deploying next-generation intrusion prevention systems and traffic monitoring tools can help detect and mitigate DDoS attacks.

Unusual Traffic Between Ports

Observing network traffic patterns that deviate from your organization’s typical activity, such as unexpected connections between specific ports, can raise red flags.

Utilizing network monitoring tools and security information and event management (SIEM) solutions can help identify these anomalies.

Unauthorized Changes to the Registry or System Files

Any unauthorized modifications to critical system files, configuration settings, or the Windows registry may indicate the presence of malware or an attacker attempting to gain persistent access.

If you note an unexplained increase in user access privilege requests, further investigation is recommended. Host-based IOCs, such as changes to registry configurations, keys, system file hashes, and other unusual signs of suspicious registry activity, can be monitored to detect these types of security events.

Unexpected Requests for Increased Access Privileges

Further investigation is recommended if you note an unexplained increase in user access privilege requests.

These requests may be coming from unauthorized users attempting to infiltrate your networks. Robust access management policies and monitoring for anomalous privilege activity can help mitigate this risk.

Having looked at some common specific IoCs, we need to understand the different categories of compromise indicators. As we’ll see below, many IoCs can be categorized as email-based, host-based, or network-based.

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Types of Indicators of Compromise

Email Indicators

Email-based indicators of compromise are red flags that go off in your email inbox should you receive suspicious emails. 

These indicators can range from an unexpected increase in spam to emails with strange file attachments, suspicious files, or unrecognized file names. If you see any of these unusual file activity signs, you must immediately protect your computer from further infection.

Host Indicators

Security professionals can use host-based indicators of compromise to determine whether a system has been compromised and, if so, the scope of the compromise. Host-based indicators can include file signatures, registry keys, process IDs, network connections, and other system data.

Security analysts and cybersecurity experts use various methods, including manual analysis and automated scanning, to collect indicators of compromise from hosts.

Network Indicators

Network-based indicators of compromise are any data or activity on a network that could indicate that the network has been compromised. They can include forensic evidence such as abnormal traffic patterns, sudden changes in user behavior, access from malicious IP addresses, repeated incorrect log-ins, or malware infections.

Network-based indicators of compromise are vital to monitor because they can provide evidence of bad actor activity even if no malware is on the victim’s computer. This makes them useful for detecting cybercriminal attacks that use sophisticated techniques like spear phishing or watering hole attacks.

Behavioral Indicators

Behavioral indicators of compromise are patterns of suspicious behavior and activity that can suggest a user account or system has been compromised.

These might include attempts to access unauthorized resources, unusual login times, or unexpected changes in user behavior. Security teams can identify potential threats and respond quickly by monitoring for these behavioral clues.

Why Your Organization Should Monitor for Indicators of Compromise

The cost of a data breach can be high. For example, in the United States, the average cost of a data breach is over $9 million. This includes the cost of investigating the breach, notifying customers, and repairing damage to the company’s reputation.

Rest assured, monitoring IoCs is one of the most effective ways for a company to mitigate cyberattack damage. By identifying these indicators, companies can detect breaches early and minimize the damage.

The importance of your role in the early detection of indicators of compromise cannot be overstated. It is crucial because it allows companies to respond quickly and limit the scope of the breach. The sooner a breach is detected, the less time the attacker has to steal data, disrupt operations, or cause other damage.

Additionally, monitoring for indicators of compromise can help companies gather valuable threat intelligence. By analyzing the patterns and characteristics of the indicators, security teams can better understand the tactics, techniques, and procedures (TTPs) used by threat actors.

This intelligence can strengthen defenses and improve incident response times and capabilities, helping organizations prepare for and mitigate future attacks.

What Can We Learn from Monitoring Indicators of Compromise?

Careful monitoring of IoCs is essential for protecting an organization’s networks and data. Many indicators of compromise can be monitored, including system files, network traffic, user behavior, and malware.

These indicators can provide valuable information about an organization’s security posture. By tracking indicators of compromise, organizations can quickly identify when something is amiss and take steps to mitigate the threat. In addition, by detecting and responding to threats early, organizations can minimize the damage a data breach could cause.

How to Monitor for Indicators of Compromise

You have several options for monitoring indicators of compromise (IoCs). Training employees and investing in comprehensive security tools is a great place to start.

Raising Employee Awareness

Training employees on indicators of compromise is critical in defending your organization against cyberattacks. Remember: your end users (employees) are your first line of defense against cyberattacks. They often first notice something is wrong with the network or an email they received. Therefore, it is crucial to train employees to recognize indicators of compromise so they can report them quickly.

UEBA & DLP Tools

Various tools can help monitor for indicators of compromise. One such tool is UEBA, or User and Entity Behavior Analytics.

UEBA software uses artificial intelligence and machine learning algorithms to detect malicious or unauthorized activity. It can also identify abnormal behavior, such as employees accessing files they usually wouldn’t or logging in from an unusual location.

Many organizations use UEBA endpoint monitoring tools to detect indicators of compromise on their systems. These tools collect data from devices on the network to establish a behavioral baseline and then monitor and analyze user activity for signs of unusual or abnormal activity.

DLP tools provide a comprehensive solution that monitors user activity, tracks file transfers, and notifies you when indicators of compromise, such as careless security practices, are detected. Extended detection and response (XDR) capabilities can help organizations identify and respond to security incidents in real time.

Indicators of Compromise vs. Indicators of Attack: What’s the Difference?

There are many indicators of compromise and indicators of attack. However, the difference between these two types of indicators can be blurry.

An Indicator of Compromise is an unexpected activity that may indicate that a system has been compromised. For example, a change in normal user behavior or a surprising increase in traffic might be signs of a compromise.

On the other hand, an Indicator of Attack indicates that an attack is in progress. For example, malware signature detection or abnormal network activity attacks in progress could be signs of an attack.

Determining whether a particular event indicates a compromise or an active attack can be difficult. Sometimes, it’s unclear which category an event falls into until further analysis has been performed. That’s why businesses need to monitor for both.

The Best Tool to Monitor Indicators of Compromise

Early detection is critical to preventing data breaches. Organizations need to monitor their systems for indicators of compromise so they can react before sensitive data is compromised. Several tools can help organizations do this, but not all are created equal.

As an insider threat prevention solution, Teramind offers a comprehensive solution that monitors for multiple indicators of compromise. So whether you need to monitor for abnormal user behavior, set up security alerts, or scan for potential insider threats, their endpoint monitoring tools give you the best protection.

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An organization’s IT infrastructure is constantly under attack from various sources. While some attacks are easily recognized, others can be more subtle and go undetected for long periods. Therefore, to maintain the security of an organization’s systems and data, it is vital to be aware of the various indicators of compromise that could indicate a breach has occurred.

Investing in best-in-class tools like Teramind’s DLP and UEBA solutions empowers you to detect, diagnose, and repair breaches quickly before data is lost or stolen. By leveraging advanced security solutions and threat intelligence feeds, organizations can build a robust security strategy to stay ahead of sophisticated cyber threats.


What is an example of an indicator of compromise? 

An example of an indicator of compromise is a sudden increase in network traffic or a significant change in user behavior. These anomalies may suggest a system has been compromised and require further investigation.

What is an example of an IoC? 

An example of an Indicator of Compromise (IOC) is a sudden increase in network traffic or a significant change in user behavior. These anomalies can indicate that a system has been compromised and should be investigated further. Monitoring such indicators is crucial to prevent data breaches and protect sensitive information.

What is an indicator of compromise standard? 

An indicator of compromise standard refers to guidelines or criteria that help organizations identify potential signs of a security breach or compromise. These standards establish a framework for monitoring systems and networks for suspicious activities or anomalies, enabling organizations to respond promptly and mitigate risks.

What are the three types of IoCs? 

The three common types of IoCs, or Indicators of Compromise, are behavioral, network, and host-based indicators. These indicators can help organizations detect and respond to potential attacks by monitoring for abnormal user behavior, unusual network traffic, and suspicious activities at the host level.

What is a behavioral indicator of compromise? 

Behavioral indicators of compromise are patterns of suspicious processes that can indicate a system has been compromised. These indicators include unusual login times, multiple failed login attempts, or employees accessing sensitive information they do not typically need for their jobs. Monitoring these indicators is crucial for detecting and responding to potential security breaches.

What are examples of behavioral indicators? 

Behavioral indicators of compromise suggest a deviation from normal user behavior and may indicate a security breach. Such indicators include changes in login patterns, excessive file access or sharing, or access to unauthorized resources. Monitoring and analyzing these behavioral indicators can help organizations identify and respond to potential security threats.

What is analyzing indicators of compromise? 

Analyzing indicators of compromise involves monitoring for potential signs of a security breach or compromise. These indicators can include sudden increases in network traffic, changes in user behavior, or other anomalies that suggest a system has been compromised. Organizations can respond promptly and mitigate risks to their systems and data by identifying and analyzing these indicators.

What are threat hunting indicators of compromise?

Indicators of compromise (IoCs) are signs or clues suggesting an attacker breached or compromised a system. Examples of IoCs include sudden increases in network traffic, significant changes in user behavior, and anomalies in system security logs. Analyzing these indicators of compromise helps organizations detect and respond to security incidents, protecting their systems and data from potential threats.

Why are indicators of compromise important? 

Indicators of compromise are essential because they can help organizations detect and respond to potential security breaches. By monitoring for anomalies such as sudden increases in network traffic or changes in user behavior, organizations can identify signs of compromise and take the necessary steps to mitigate risks.

What is an advantage of detecting indicators of compromise? 

Indicators of compromise are essential because they help organizations detect potential security breaches and protect sensitive information. Detecting these indicators allows for prompt response and mitigation of risks, providing an advantage in maintaining system and data security.

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