Demystifying Intrusion Detection Systems (IDS)

As cybersecurity threats continue to increase, the defenses businesses use against them also have to increase. While firewalls are still considered a core part of network security, they are now considered insufficient on their own. They need to be backed up by an Intrusion Detection System (IDS). Here is a quick guide to what you need to know about IDSs.

IDS vs firewall

Although an IDS and a firewall are both frontline defenses against intrusion, they operate in very different ways. Here is an overview of the three main ways an IDS differs from a firewall.

Purpose: An IDS monitors traffic and aims to identify patterns indicative of potential security threats. A firewall acts as a barrier between a trusted internal network and untrusted external networks, controlling incoming and outgoing traffic based on predetermined security rules.

Deployment location: An IDS is deployed strategically within the network to analyze traffic and detect potential threats. It can be network-based (NIDS) or host-based (HIDS). A firewall is deployed at the network perimeter or between network segments, regulating the traffic entering or leaving the network.

Mechanism of action: An IDS alerts administrators or security personnel to investigate and respond to potential breaches. Firewalls actively enforce access policies by allowing or blocking traffic based on predefined rules.

Common cyber threats an IDS can detect

As you might expect, there is a lot of crossover between the threats an IDS can detect and the threats a firewall can detect. Essentially, using an IDS and a firewall gives you two chances to block common threats. Here is an overview of the five main threats an IDS defends against).

Malware

An IDS employs signature-based detection to identify known patterns or signatures of malware and viruses within network traffic. This includes recognizing the unique code sequences or characteristics associated with specific malicious entities.

It will also flag activities indicative of malware infections. These include unusual file access patterns, unauthorized system modifications, and unexpected communication with malicious domains.

Unauthorized access attempts

An IDS analyzes login behavior to identify how legitimate users behave. It then monitors user behavior and alerts when it detects unusual patterns of user authentication. For example, if it notices multiple failed login attempts from different locations in a short time it will alert that a brute force attack may be in progress.

DoS and DDoS attacks

IDS establishes a baseline of normal network behavior and traffic. It will then alert if it detects usual activity. This could include abnormal spikes in network traffic, a sudden increase in data transfer, or irregular access times. This not only prevents known threats such as (D)DoS attacks but also catches novel threats that lack predefined signatures.

SQL injection and cross-site scripting (XSS) attacks

IDS utilizes pattern matching to detect SQL injection attempts and XSS attacks by identifying malicious code patterns in web requests. It scrutinizes input parameters and identifies attempts to manipulate queries or inject malicious scripts.

Network Scanning and reconnaissance

An IDS detects patterns indicative of network scanning activities, where attackers probe for open ports and vulnerabilities. Unusual scanning behavior triggers alerts, allowing administrators to preemptively respond to potential threats. It also identifies enumeration attempts, where attackers seek to gather information about network resources.

Advantages of implementing an IDS

Here are the three main advantages of implementing an IDS.

Early threat detection: IDS provides proactive monitoring of network traffic, swiftly identifying and alerting security teams to potential threats. This early detection capability enables organizations to respond promptly to emerging cyber threats, preventing or minimizing the impact of security incidents.

Incident response enhancement: By continuously analyzing network activities, IDS aids in incident response by providing detailed insights into the nature and scope of security incidents. Security teams can leverage these insights to rapidly investigate and mitigate threats, reducing the time it takes to identify and address security breaches.

Regulatory compliance and reporting: Many regulatory frameworks mandate robust security measures and incident reporting. Implementing IDS assists organizations in achieving and maintaining regulatory compliance by actively monitoring security events, generating detailed reports, and facilitating timely disclosure of incidents to relevant authorities.

Challenges in IDS implementation

Here are the three main challenges of implementing an IDS.

False positives and negatives: IDS systems may incorrectly identify benign activities as threats and/or miss actual security incidents. This is part of the reason why they work best in combination with complementary tools such as firewalls.

Integration with existing security infrastructure: Ensuring seamless integration with diverse security tools and infrastructure poses a challenge. Compatibility issues may arise, requiring careful configuration and coordination to achieve effective collaboration.

Resource intensiveness and scalability: IDS implementations demand significant computational resources, and scaling these systems to accommodate growing network demands can be resource-intensive. Organizations must carefully manage resource allocation to maintain optimal IDS performance.