What Is an Intruder Detection System?

Cyber attacks are evolving at a high rate daily, creating an alarming situation for all business owners of the digital world. Crafting effective security policies will not help alone. It is more important to tighten security gaps within their networks and digital resources.

Everybody needs to realize that it is better to implement preventive measures instead of mitigating the loss after an attack. For that, it is crucial to enable intruder detection systems to detect the attacks and risks, so you can act promptly to prevent them from causing any damage.

An intruder detection system helps you protect sensitive data and network integrity. Learn more about this system, its types, its importance, and much more in this article.

Introduction To Intruder Detection System IDS

Networks and servers of big companies and organizations are constantly exposed to security threats. The intrusion detection system monitors traffic and detects security threats and intruding activities trying to penetrate the network.

It is available in the form of a system, device, or software application. As soon as it detects malicious activity or abnormal data packets, it instantly sends alerts to the administrator. The administrator immediately counteracts the attack upon receiving alerts and protects the system.

Intruder Detection System is often confused with Intrusion Prevention Systems (IPS), which have similar functions but different features. In addition to monitoring and reporting suspicious traffic, IPS can prevent malicious traffic from invading further without the involvement of IT professionals. In comparison, the job of the Intrusion Detection System ends with alerting the administrator. IPS stands a step ahead of IDS; however, no difference lies in the performance of IDS and IPS when detecting attacks.

How Intrusion Detection System Works

There are three methods by which IDS performs the intended task. Scroll down to acknowledge how it works so smartly.

Signature-based Intrusion Detection System (SIDS)

According to this method, IDS uses malicious instruction sequences, referred to as patterns and signatures, of the incoming traffic to identify its nature. It has some signatures of common attacks stored in its database.

It compares the database signature with the traffic signature. If both are the same, it sends alarms to the concerned administrator. Otherwise, it allows the data packets to enter the network.

Anomaly-based Intrusion Detection System (AIDS)

AIDS works by comparing two behavior models; the one developed for normal traffic and the other shown by suspicious activity. IDS uses machine learning to develop an expected model of genuine activity and matches it with the activity’s original model. If it finds a difference between the two, it recognizes the activity as a suspected intrusion and instantly flags the admin. Since this detection method does not follow predefined patterns, it can detect unknown malicious activities with machine learning.

Hybrid Intrusion Detection System

It features a combination of SIDS and HIDS capabilities, which makes it equally suitable for known and novel attacks. When traffic arrives, it analyzes if the packets’ signature matches any of the sequences from the database. If it finds a perfect match, alarms are generated. Else, an anomaly-based detection technique is used to compare traffic behavior with normal behavior.

Types Of Intrusion Detection System IDS

Intrusion detection systems can be divided into two broad types, which are as follows:

Network Intrusion Detection System (NIDS)

This threat detection system monitors network traffic to and from the devices. Professionals install it at the most favorable location so that it can extend its detection services to the entire network.

Since it is designed to provide network security, it cannot detect data traveling to individual network devices. However, it efficiently reports malicious threats taking place on the network surface.

Host Intrusion Detection System (HIDS)

Host Intrusion Detection Systems ensure deep analysis of the traffic received by network devices or hosts, which NIDS cannot achieve. Each data packet and system file traveling to and from the endpoints passes through this system to detect deleted, altered and misconfigured content. In case a system file does not appear as it should, it triggers the alarms.

Additionally, if a malicious activity goes undetected by network intrusion detection systems, it will likely get detected by HIDS. While searching for content abnormalities in packets, HIDS sometimes triggers false alarms upon discovering non-malicious abnormal behaviors.

How Intrusion Detection System Can Be Useful

Intrusion Detection Systems are significantly important for digital data protection needs. Additionally, they help us with various security-related tasks. Let’s see how!

Enhances Network Security

IDS monitors inbound and outbound traffic and precisely observes the signatures and behaviors of network packets. It quickly identifies malicious activities and allows you to take the necessary action against that activity. Thus, your network resources stay safe from unauthorized access.

Determines Security Weaknesses

Alongside threat alerts, IDS also gives information about the network areas targeted by nefarious actors. This information helps you identify your network’s vulnerabilities and security gaps, allowing you to make security improvements.

Helps Chase Actors

If you are willing to trace the attacker, IDS can help you out. It can provide the source address from where the activity was hosted or triggered.

Helps Control Cyber Attacks

IDS also notes some critical details of intrusion practices, such as the type of attack, techniques adapted to launch the attack, and the resources being targeted. Cybersecurity professionals can use this information to analyze the nature and complexity of cyber attacks. This way, they can review and update security strategies, solutions, and tools to efficiently prevent and mitigate real-world threats.

Makes Data Organization Convenient

IDS gives information about which data and network resources incur attacks more frequently. With this, you can determine which files or information are critically valuable, so you can separate them from less important content and keep them sorted. Organizing a massive amount of data without the help of IDS would be a lot of hassle.

Limitations Of Intrusion Detection Systems

Installing intrusion detection systems improves network security to a great extent. Sometimes, IDSs fail to meet this goal due to the following limitations:

False Alerts

In some situations, Intrusion Detection Systems do not detect accurately and hence generate false positives or false negatives. For example, during anomaly detection, IDS only accepts activities whose behavior matches a trusted behavior. However, an anomalous behavior does not necessarily mean the activity is a security attack. So, if it is a legitimate activity, the alarm turns out to be a false positive.

Inability To Interpret Encrypted Traffic

IDSs cannot read encrypted data. So, those trying to attack a system go for an encrypted file to escape the detection system. They hide malware in encrypted packets, which then affect computer systems.

Signature Updates

Signature-based IDS analyzes incoming network traffic, comparing it with database signatures. The more signatures the database contains, the more known attacks IDS can detect. Therefore, frequently updating signatures is essential to improve the functionality of SIDS.

How Attackers Attempt To Evade Intrusion Detection Systems

Cyber attackers use the following evasion techniques to bypass an IDS successfully:

DoS Attack

Flooding and fragmentation are two of the most common types of evasion techniques. Attackers attempt to overwhelm the centralized logging server with floods of TCP and UDP packets. Once the server is overloaded, it loses the ability to process further packets. Thus, the unprocessed packets manage to enter the network.

Another DoS technique includes making small fragments of these packets to allow attackers to launch the attack while the IDS remains busy reassembling packets.

Malware Encryption

As encrypted files can not be penetrated, the content within such files is not monitored by IDS. Actors encode malware software, file, or e-mail to escape IDS and reach the victim smoothly.

Address Spoofing

This technique involves the misconfiguration of source addresses to trick an IDS. Attackers change their addresses to appear as legitimate sources or use incorrectly configured proxy servers that go undetected by IDS. Consequently, IDS give false negatives, facilitating cyber-attacks.

Scanning Attacks

Attackers sneak into sensitive server information, like open and closed ports, acceptable traffic criteria, etc., by sending packets to a network. They use this information to identify the network’s vulnerabilities and points from where they can escape IDS.

Is Firewall The Same As Intrusion Detection System?

IDS detects threats carried by data packets exchanged between external sources and network resources. It can not respond to those threats. However, firewalls detect abnormal traffic behavior and block threats by restricting unauthorized access.

IDS works well for both external and internal traffic. In contrast, a firewall handles external traffic only and can not detect internal security risks.

Final Thoughts About Intrusion Detection Systems

Network traffic carries various bugs, infected codes, and untrustworthy behaviors that can cause system disruption, data theft, and other costly consequences. Therefore, it is crucially essential to monitor network traffic through IDS.

An enabled IDS also offers additional benefits, such as tracking attacking practices and source details.

Derik Belair

As President and CEO, Derik leads the vision, strategy and growth of Augmentt. Prior to founding Augmentt, Derik was the Vice President at SolarWinds, leading the digital marketing strategy for SolarWinds’ Cloud division. Derik has been working in the channel for over 20 years, starting his career as a channel sales rep at Corel Corp. and eventually becoming the first employee at N-able Technologies in April of 2000.
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