What Is an Intrusion Detection System?

As the name suggests, an Intrusion Detection System or IDS is a security system that helps you detect a potential attack against an application, network, or computer. Since it is a detection system, its core job is to detect and report a potential security attack to the administrator.

Cyber attackers are skilled at identifying and exploiting security loopholes in a system or network. While IDS can detect a possible threat, it cannot do anything to thwart it except report it.

While this answers the question of what is intrusion detection system is, in this article, we will talk about an IDS System and understand how it works.

How does IDS work?

Since an IDS needs to detect a possible threat, it is not placed in the real-time communication path between the receiver and sender of information. It analyses a copy of the traffic stream. This ensures that it does not interfere with network performance while doing its job.

The purpose of IDS in cyber security is to stop a hacker or a cyber-miscreant before any damage is done to the network or application. It creates a track of the network and system activities and then starts looking for deviations or anomalies.

It can identify events like Christmas tree scans, DNS poisoning, etc. Interestingly, you can implement an IDS network as a security device or an application.

An IDS detects threats using the following two methods:

Signature-based Method: The IDS identifies an attack based on certain patterns in this method. If there are some commonly known malicious codes, then IDS understands the pattern of the code and tries to find them in incoming traffic. Hence, this method is applicable only when the signature of the attack is recorded in the system.
Anomaly-based Method: In this method, IDS creates an activity model by using machine learning. It then compares any suspected code or activity with the model to determine its trustworthiness.

Types of IDS Detection

IDS detection is of five types as described below:

NIDS or Network-based Intrusion Detection System

This monitors a protected network by analysing all incoming and outgoing traffic from various devices on the network. It looks at metadata and packet contents to determine threats, if any. It is deployed at crucial points on the network.

HIDS or Host-based Intrusion Detection System

This IDS is specifically designed to detect threats to a host computer. Hence, it focuses on analysing the traffic to the computer and identifying any malicious activity.

PIDS or Protocol-based Intrusion Detection System

This IDS system is designed for a web server. Hence, its job is to examine the server and user protocol.

APIDS Application Protocol-based Intrusion Detection System

This is an application-specific IDS. It monitors and analyses application protocols. This helps it identify any deviations and report them immediately.

HIDS or Hybrid Intrusion Detection System

This combines two or more IDS approaches. Hence, you can use this to tailor the detection system as per your preferences.

Benefits of Intrusion Detection Systems

Hackers are evolving and using technological advancements to create newer tactics for gaining unauthorised access to servers, networks, and applications.

Hence, network security technologies must keep pace and stay ahead of the hackers. An Intrusion Detection System plays an integral part in the protection of a network and offers the following benefits:

Identify any malicious activity or threat and inform the administrator before damage is done.
Detect various cyber threats like malware infections, data breaches, etc.
Monitor and analyse network traffic in real-time, ensuring immediate reporting of any suspicious event.
Identify known threats quickly by matching patterns or signatures of known malicious activities.
Conduct behavioural analysis to identify new threats with no recorded signature.
Ensure regulatory compliance.
Provide insights into network traffic and help optimise the overall network performance.
Saves costs in the long run since the financial implications of a security breach can be huge.

Intrusion Detection Systems are good but can only detect a threat. Hence, most organisations use them with an Intrusion Protection System or IPS that can take action against a threat.

Combined with Vulnerability protection, Antivirus, Antimalware, and Antispyware, these two can make for a comprehensive threat prevention solution.

How hackers avoid detection by IDS

If you are planning to deploy the IDS network, make sure you know how hackers try to avoid it. This can help you create security policies accordingly.

Attackers fragment the file into small parts. Hence, IDS does not identify it as a threat since no signature exists. These fragments are reconstructed after passing through IDS.
Another popular way is called Flooding. In this method, the attacker tries to overwhelm IDS by flooding it with too many activities and crashing it or using the traffic to hide malicious activities.
Some attackers might alter the program code in a manner that makes it undetectable by IDS.
Attackers can also use encryption to hide attacks and avoid being detected by IDS.

Summing Up

We spoke about what IDS is, how it works, the different types of IDS detection, and the benefits an IDS system offers.

This should give you a good understanding of an Intrusion Detection System. If you are thinking of boosting the security infrastructure of your organisation, then consider adding IDS to the list of tools and systems.

FAQs for Intrusion Detection System

Q1. How does an IDS differ from a firewall?

A firewall is a barrier that ensures nobody can access the server or network without authorisation. On the other hand, an Intrusion Detection System analyses incoming and outgoing traffic to spot a potential threat or attack. Hence, they serve two very different purposes.

Q2. Is IDS effective against modern cyber threats like zero-day exploits?

Signature-based IDS systems might not be able to detect modern cyber threats. However, advanced IDS systems with Anomaly-based detection can be effective against such threats.

Q3. Can IDS be deployed in cloud environments?