There are numerous tools to detect attacks and exploits and take steps to block or stop cyberattacks. Firewalls prevent unauthorized traffic from entering the network, spam filters reject unwanted email messages, and antimalware tools protect endpoints from malware are just a few examples of tools that are universal across just about every organization, regardless of size or industry. Another valuable security tool that is almost as ubiquitous is a network intrusion detection system (IDS). Here’s what you need to know about a network IDS and how it can help you protect your network and secure data.

What Is an IDS?

So, what does an IDS do? One definition for IDS explains that it is a security service that monitors and analyzes network or system events for the purpose of finding, and providing real-time or near real-time warning of, attempts to access system resources in an unauthorized manner.

Unlike a firewall, which sits at the perimeter and acts as a gatekeeper to monitor network traffic and determine if it should be allowed into the network or endpoint at all, an IDS focuses on the traffic that is on the internal network to identify any suspicious or malicious activity. This allows an IDS to detect attacks that manage to slip past the firewall, as well as attacks originating from within the network.

Most IDS solutions use a combination of signature-based detection, which compares traffic against a database of known attacks or attack techniques, and anomaly-based detection, which simply looks for suspicious activity or behavior that is strange or varies significantly from the established norm to detect threats.

Why You Need Network IDS

No firewall is foolproof, and no network is impenetrable. Attackers continuously develop new exploits and attack techniques designed to circumvent your defenses. Many attacks leverage other malware or social engineering to obtain user credentials that grant them access to your network and data. A network intrusion detection system (NIDS) is crucial for network security because it enables you to detect and respond to malicious traffic.

The primary benefit of an intrusion detection system is to ensure IT is notified when an attack or network intrusion might be taking place. A network intrusion detection system (NIDS) monitors both inbound and outbound traffic on the network, as well as data traversing between systems within the network. The network IDS monitors network traffic and triggers alerts when suspicious activity or known threats are detected, so the IT team can examine them more closely and take the appropriate steps to block or stop an attack.

Taking Action on Network IDS Alerts

Network IDS is crucial for comprehensive security, but effective use requires some considerations. While monitoring and analyzing network traffic for suspicious or potentially malicious activity, false positives and false negatives can occur. Therefore, it’s essential to have IT personnel with the expertise to interpret IDS alerts accurately and take appropriate action.

False positives

Signature-based threat detection is generally accurate. But when it comes to anomaly-based detection and identifying potentially suspicious or malicious activity, you will likely encounter false positives. A false positive is when the network IDS flags normal activities or legitimate traffic as suspicious or malicious. The intrusion detection system needs to have a solid baseline of what normal traffic looks like and be properly tuned to ignore legitimate or allowed traffic.

False negatives

On the other side of the spectrum from false positives, you also face a risk that suspicious or malicious activity will not be detected 100 percent of the time. This is particularly an issue with zero-day attacks or emerging threats that rely on new exploits and attack techniques that the IDS is unfamiliar with.

Security experts

With a network IDS, the biggest challenge — aside from false negatives and false positives — can be the sheer volume of alerts. One of the most important elements of using a network intrusion detection system effectively is ensuring you have security personnel with the knowledge and skills to necessary weed out false alarms and identify suspicious or malicious traffic the network IDS might have missed.

Attacks don’t have work hours — they occur around the clock every day. You should have a security operations center (SOC) with experts who can monitor alerts and analyze log data to identify and prioritize potential attacks and take the appropriate action to block the traffic or thwart the attack.

A network IDS is just one important element of an overall security strategy within a managed detection and response (MDR) solution. With Fortra’s Alert Logic MDR, your comprehensive coverage includes our industry-leading network IDS across hybrid, cloud, and on-premises environments. Our always-on threat monitoring means we can detect network faster that can lead to shorter attacker dwell time and less damage to your environment.

Fortra's Alert Logic Staff
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Fortra's Alert Logic Staff

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