It’s a well-known fact that sometimes malicious or anomalous activities can occur on a system, thus making the existence of a host intrusion detection system extremely important.

A host intrusion detection system’s job is to detect the nefarious activities taking place and send them for analysis, in order to be understood and stopped before causing real damage.

Today we are taking a deep dive into finding out what HIDS is, why you need it and why it is important to have it.

What is HIDS (Host Intrusion Detection System)?

HIDS stands for host-based intrusion detection system and represents an application that is monitoring a computer or network for suspicious activities. The activities monitored can include intrusions created by external actors and also by a misuse of resources or data internally.

How Does HIDS Work?

Imagine a security system that alerts you of any anomalous activities taking place in your company’s IT infrastructure.

HIDS software works in a similar way, by logging the suspicious activity and reporting it to the administrators managing the devices or networks in question.

It’s common knowledge that most applications that are running on devices and networks can and will create log messages of the activities and functions performed while a session is active. You can collect and organize all the data created by yourself, but this will quickly become expensive from a time management perspective – that is just because of the sheer volume of data that you need to keep track of.

HIDS tools monitor the log files generated by your applications and create a historical record of activities and functions, therefore allowing you to quickly identify any anomalies and signs of an intrusion that may have occurred.

A host intrusion detection system tools also compile your log files whilst allowing you to keep them organized and makes it easy for you to search or sort the files by application, date, or other metrics.

HIDS Detection Methods

Most HIDS systems utilize a combination of these 2 methods:

Host Intrusion Detections Systems Based on Signatures

This type of intrusion detection system is focusing on searching for a previously known pattern, identity, or a specific intrusion event. Most IDSs are coming from a definitions database that needs regular updates to keep up with regular and known cyber threats. As long as the database is up to date this type of IDS will do a good job.

However, attackers can make small changes to their attack methods so that databases cannot keep up in real-time.

Host Intrusion Detections Systems Based on Anomalies

As opposed to signature-based HIDS, anomaly-based ones rely more on analyzing “trustworthy behavior” and use machine learning techniques to flag malicious behavior. This will translate sometimes into a higher false-positive rate, as the system will also flag legitimate behavior as well.

Anomaly-based IDS is a good option for determining when someone is probing your network prior to a real attack taking place. The success of this type of IDS also depends on the degree of distribution across the network and the level of training provided by the IT admins.

Why Do You Need a Host Intrusion Detection System?

If you are still not convinced we can go deeper and say that the key function that makes HIDS a must-have is the detection feature, which saves you the need to sort through the log files for unusual behavior once they’re organized and compiled.

A host intrusion detection system uses rules and policies in order to search your log files, flagging those with events or activity the rules have determined could be indicative of potentially malicious behavior.

By definition, all IT Admins are supposed to be the most familiar with the systems they are managing and with the operations they are running. That is why they are the best candidates when it comes to defining the rules their HIDSs will be using when scanning log files. All admins can and should take advantage of the predefined rules already built into the system. All preset rules have been written by security experts and they help to find common signs of intrusion.

The entire purpose of HIDS software is to make the detection process easier for administrators, freeing up your team’s resources to deal with other day-to-day responsibilities.

HIDS is not the only tool that admins have at hand in order to deal with malicious activities, aside from the host intrusion detection system there also exists NIDS  – Network Intrusion Detection System.


HIDS looks at particular host-based behaviors (at the endpoint level) including what apps are utilized, what files are accessed, and what information is stored in the kernel logs.

NIDS examines the data flow between computers, often known as network traffic. They basically monitor the network for unusual activity.

As a result, NIDS can identify an attacker before he can perform a breach, while HIDS acts as a second layer of defense and take action at the endpoint level if the system is breached.

If you’re wondering which Intrusion detection system you should use, it might be a good idea to start looking also at Security Information and Event Management. This is the subsection of computer security services that bring together both NIDS and HIDS solutions that provide real-time analysis of security alerts generated by applications and network hardware.

Thus, you will need both NIDS & HIDS for a solid security regimen. They usually work together & complement each other’s capabilities.
NIDS allows for a fast response as real-time data monitoring can trigger alerts but while HIDS analyses logged files for signs of malicious activity.

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The host intrusion detection system also allows you to examine historical data in order to determine activity patterns which are useful particularly to detect activity from experienced hackers who often vary their methods of intrusion to be more unpredictable and therefore less easily traced.

In conclusion

Each system complements the other, creating a more comprehensive intrusion detection system.

HEIMDAL™ Threat Prevention is the right choice as it stops even the hidden threats using AI at the Perimeter-level with Network Prevention, Detection, and Response tool as well as with the experience of complete DNS protection.

You don’t need to have any solution installed on your endpoints, this being crucial when malicious actors engage in traffic-sniffing attacks or your employees are using their personal (and potentially compromised) devices.

What Is EDR? Endpoint Detection and Response

Security Information and Event Management (SIEM). What It Is and How It Works.

What Is an Intrusion Prevention System – IPS?

Taking Host Intrusion Prevention System (HIPS) Apart


Thanks for the awesome article. Very insightful!

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