Intrusion detection systems (IDS) are found in cyber security strategies all around the world. These simple, yet effective tools provide a strong first line of defense for organizations of all sizes. Even more compelling than the functionality of IDS is the ability to enjoy a modern alternative that includes all the power and features of an IDS without any of the challenges. In this introductory guide to IDS, we will explore:

• IDS Basics
• Benefits
• Types of IDS Systems
• Switching to a Modern Alternative

What is intrusion detection?

Intrusion detection is the idea of continuously monitoring a system or network for unauthorized access attempts or malicious activity. Intrusion detection techniques often include monitoring traffic, comparing traffic to a set of predefined rules or signatures, and then issuing alerts when traffic matches a malicious pattern.

Intrusion detection usually concentrates on identifying and reporting potential security breaches rather than preventing them outright, though there are exceptions to this. Early detection of intrusions allows security teams to take action and minimize damage. This can involve isolating infected devices, blocking attackers, or launching incident response procedures.

What is an intrusion detection system (IDS)?

An intrusion detection system (IDS) is a cybersecurity tool that analyzes system activity or network traffic for patterns that might indicate an attack. These patterns could be:

• Unusual login attempts (repeated failed logins, access from unexpected locations)
• Attempts to exploit known vulnerabilities in software
• Denial-of-service attacks flooding the system with traffic

By identifying these patterns, IDS helps security personnel identify potential threats and take necessary steps to mitigate those threats. There are two main types of intrusion detection systems:

• Network Intrusion Detection System (NIDS): This type of system monitors network traffic for suspicious activity, such as port scans, denial-of-service attacks, or attempts to exploit vulnerabilities.
• Host-based Intrusion Detection System (HIDS): This type of system is installed on individual devices and monitors the activity on those devices for suspicious activity.

When an IDS detects suspicious activity, it will typically send an alert to a security administrator. The security administrator can then investigate the alert and take appropriate action, such as blocking the attacker's IP address or shutting down a compromised device.

Intrusion detection systems are an important part of a layered security defense. They can help to identify and respond to attacks that other security measures, such as firewalls, may miss. However, it's important to note that IDS systems are not foolproof and can sometimes generate false alarms or cause alert fatigue.

What are the 5 components of an IDS?

Intrusion detection system software can be broken down into 5 essential components that work together to detect suspicious activity:

1. Sensors (Data Acquisition Units): These modules function as the primary data collection mechanism for the IDS. They are deployed at strategic points within the network (network sensors) or on individual hosts (host-based sensors). Network sensors continuously capture and transmit network traffic data to the IDS for analysis. Host-based sensors monitor system activity on the device, including logs, file access attempts, and running processes.
   
   
2. Data Processing and Analysis Engine: The analysis engine is the core component responsible for evaluating data collected by the sensors. It employs various techniques to identify potential intrusions:
   
   
   • Signature-based Detection: This approach involves matching captured data against a database of known attack signatures. These signatures represent characteristic patterns of malicious activity.
   • Anomaly Detection: This technique involves employing statistical algorithms to establish baselines for normal network traffic or system activity. The engine then identifies significant deviations from these baselines as potential intrusions.
     
     
3. Alert Generation Engine: Upon detecting suspicious activity, the analysis engine triggers the alert generation engine. This engine is responsible for formulating alerts that include details of the suspected intrusion, such as the type of activity detected, its timestamp, and the source IP address. These alerts are then disseminated to:
   
   
   • Security Personnel: For investigation and response actions.
   • Security Information and Event Management (SIEM) System: A central repository that aggregates security events from various sources, including IDS alerts, to facilitate a comprehensive view of security posture.
     
     
4. Management Interface: This software component provides a user interface for security administrators to interact with the IDS. It allows them to:
   
   
   • Configure the IDS: This involves defining security rules for anomaly detection, managing sensor deployment, and establishing alert thresholds and destinations.
   • Monitor System Activity: Security personnel can utilize the console to view real-time data on detected threats, analyze historical data, and investigate security incidents.
     
     *It is important to note that not all IDS have a management interface available
     
     
5. Knowledge Base: The IDS maintains a repository of critical information for reference and analysis purposes. This knowledge base typically includes:
    
   • Attack Signatures: A well-maintained database of known attack signatures that facilitates signature-based detection.
   • Security Rules: Custom rules are defined by the security administrator to identify suspicious behavior specific to the organization's network or system.
   • Alert History: A chronological record of all generated alerts, including timestamps, details of the detected activity, and the current investigation status.

What are the 3 types of intrusion detection systems?

The three types of intrusion detection systems in cyber security based on detection methods are Anomaly-based, Signature-based, and Hybrid. These methods define how the IDS analyzes data to identify potential intrusions.

1. Anomaly-Based IDS: Anomaly-based IDS focuses on identifying deviations from normal behavior within a network or system. It works by establishing a baseline for normal activity by statistically analyzing network traffic or system activity over time. This baseline becomes a reference for identifying anomalies. The IDS then continuously monitors network traffic or system activity and compares the real-time data to the established baselines. Significant deviations from these baselines are flagged as potential intrusions.
2. Signature-Based IDS: Signature-based IDS relies on a predefined database of attack signatures to identify malicious activity. These signatures represent known patterns or fingerprints of network attacks or suspicious system behavior. The IDS continuously monitors network traffic or system activity and compares this data against the database of attack signatures. Any matches trigger an alert, indicating a potential intrusion attempt.
3. Hybrid IDS: A hybrid IDS combines both anomaly-based and signature-based detection methods to address the limitations of each approach. A hybrid system leverages signature-based detection for known threats and anomaly-based detection for novel attacks. This enhances the overall effectiveness of intrusion detection.

Each of these three detection methods (Anomaly-based, Signature-based, Hybrid) offers different strengths and weaknesses. Choosing the most suitable approach depends on factors like the specific security requirements of the network, the resource availability for managing the IDS, and the acceptable level of false positives.

It is also important to consider switching to a more advanced modern network security solution, such as network detection and response (NDR). Clear NDR™ - Enterprise (formerly Stamus Security Platform) is a modern NDR solution that leverages the best from IDS technology without the same challenges faced by IDS users. Learn more about Clear NDR - Enterprise.

What are the 2 main types of IDS?

There are two main categories for Intrusion Detection Systems (IDS) based on their deployment and data source:

1. Network Intrusion Detection System (NIDS): NIDS act as network monitoring devices deployed at strategic points within a computer network. Their primary function is to continuously capture and analyze network traffic data traversing a specific network segment. NIDS can be implemented in two primary ways:
   
   
   • Dedicated hardware appliances: These are specialized devices solely designed to perform NIDS functions.
   • Software applications on network servers: Existing network servers can be leveraged to host NIDS software, enabling them to perform network traffic analysis alongside other server functionalities.
     
     NIDS typically utilizes network adapter promiscuous mode. This mode allows the NIDS to capture all network traffic on the attached network segment, regardless of its intended recipient. NIDS employs two main techniques for analyzing captured network traffic data: signature-based detection and anomaly-based detection.
     
     
2. Host-Based Intrusion Detection System (HIDS): In contrast to NIDS which focuses on network traffic analysis, HIDS provides security for individual devices (hosts) within the network. HIDS function as software agents deployed directly on the operating system of the host device itself. Their primary function is to monitor and analyze activity occurring on the host device. HIDS are deployed as software agents on individual servers, desktops, or laptops within the network. A single HIDS agent is typically installed on each host device for dedicated monitoring.
   
   HIDS collects data from various sources on the host device, including:
    
   • System logs: These logs record events and activities within the operating system of the host device.
   • File access attempts: HIDS monitors attempts to access files on the host device, including successful and failed attempts.
   • Running processes: HIDS maintains a record of processes currently running on the host device.
   
   HIDS primarily utilizes anomaly-based detection techniques. By analyzing the collected data, HIDS establishes baselines for typical host activity. Significant deviations from these baselines, such as unusual file access attempts or unexpected processes running, can indicate potential intrusions or suspicious behavior.

What are the benefits of intrusion detection systems?

Intrusion Detection Systems (IDS) offer several advantages in bolstering your network or system's security posture. Here are some key benefits:

• Early Warning and Improved Threat Detection: IDS continuously monitors for suspicious activity. By identifying potential intrusions early on, IDS provides valuable lead time for security personnel to investigate and respond before attackers can inflict significant damage. This can help prevent data breaches, unauthorized access attempts, and the spread of malware.
  Enhanced Security Visibility: IDS offers a broader view of security threats across your network or system. NIDS provides insights into network traffic patterns, helping to identify potential vulnerabilities and malicious activity targeting your network infrastructure. HIDS provides visibility into activities on individual devices, uncovering suspicious file access attempts or unauthorized program execution that might go unnoticed otherwise.
• Improved Incident Response: The early warnings and detailed information provided by IDS can significantly streamline incident response efforts. Security personnel can leverage IDS alerts to prioritize threats, expedite investigations, and take appropriate actions to contain and mitigate security incidents.
  Compliance and Regulatory Requirements: Many industries and regulations mandate organizations to implement security measures for data protection. IDS can play a crucial role in demonstrating compliance with these regulations by providing audit trails and logs of detected security events.
• Defense-in-Depth Approach: IDS is a vital component of a layered security defense strategy. They complement other security measures like firewalls and access controls by providing an additional layer of intrusion detection and threat analysis. This layered approach strengthens your overall security posture and makes it more difficult for attackers to gain access to your systems.
• Reduced Risk of Data Breaches: By proactively identifying and in some cases blocking threats, IDS can significantly reduce the risk of data breaches. Early detection allows you to isolate compromised systems and prevent attackers from exfiltrating sensitive data.

It's important to note that IDS are not foolproof. They can generate false positives and may not be able to detect all types of attacks. However, their benefits in terms of early threat detection, improved visibility, and enhanced security response make them a valuable tool for any organization looking to strengthen its cybersecurity defenses.

Which type of intrusion detection system can also block attacks?

Intrusion Detection Systems (IDS) themselves typically focus on detection and alerting, not actively blocking attacks. However, there's a closely related system called an Intrusion Prevention System (IPS) that can block attacks in addition to detection. Here are the key differences:

• Intrusion Detection System (IDS): Monitors for suspicious activity and raises an alarm when a threat pattern is detected. An IDS doesn't directly interfere with network traffic or system processes.
• Intrusion Prevention System (IPS): Functions similarly to an IDS in terms of monitoring and detection. However, an IPS has the additional capability to actively block attacks it identifies as malicious. It can achieve this by taking actions like:
   
  • Dropping packets: Blocking malicious network traffic packets from reaching their intended target.
  • Closing ports: Disabling network ports that attackers are attempting to exploit.
  • Terminating processes: Stopping suspicious programs or processes that might be malicious.
    
    

Some solutions, like Suricata, offer combined intrusion detection and prevention systems that provide both detection and prevention functionalities within a single system depending on how the user configures it at set-up.

What are the basic types of intrusion?

There are several fundamental types of intrusion attacks that IDS systems are designed to detect:

1. Unauthorized Access Attempts: This is a classic intrusion scenario where an unauthorized user tries to gain access to a system or network. This could involve brute-force attacks attempting to crack passwords, exploiting known vulnerabilities in login systems, or using social engineering tactics to trick users into revealing their credentials.
2. Denial-of-Service (DoS) Attacks: These attacks aim to overwhelm a system or network with a flood of traffic, making it unavailable to legitimate users. DoS attacks can target various resources like network bandwidth, servers, or applications.
3. Privilege Escalation: In this type of intrusion, an attacker who already has some access to a system attempts to elevate their privileges to gain higher-level control. This can allow them to perform actions they wouldn't normally be authorized for, such as accessing sensitive data or modifying system configurations.
4. Scanning and Sniffing: Attackers often use scanning techniques to identify vulnerabilities in systems or networks. They might also use sniffing tools to capture network traffic and steal sensitive information like usernames, passwords, or data in transit.
5. Malware Installation: A common intrusion objective involves installing malicious software (malware) on a system. This malware can range from viruses and worms that self-replicate and disrupt system operations to Trojans that steal data or provide attackers with remote access.
6. Insider Threats: Not all intrusions originate from external attackers. Insider threats involve malicious activity by authorized users who already have access to a system or network. These insiders might misuse their privileges to steal data, sabotage systems, or install malware.
7. Social Engineering Attacks: While not a technical intrusion itself, social engineering tactics are often employed to facilitate other intrusion types. Attackers use deception, manipulation, or trickery to gain access to sensitive information, systems, or networks. Successful social engineering can provide attackers with a foothold in a system, allowing them to launch other intrusion attempts.
   
   

By understanding these common intrusion types, security professionals can configure IDS to effectively monitor suspicious activity and raise alerts when potential threats are detected.

What is an example of a network-based intrusion detection system?

Perhaps the best network-based intrusion detection system example is Suricata.

Suricata is a free, open-source IDS/IPS cybersecurity tool that acts as both an Intrusion Detection System (IDS) and an Intrusion Prevention System (IPS). It is used by organizations all around the world to detect cyber threats and monitor networks for suspicious activity.

Suricata’s strength lies in its versatility. When tuned correctly, it is a high-performance tool that can handle large volumes of network traffic and generate vast amounts of network traffic data. It is also extremely flexible, offering deep analysis of various protocols and the ability to customize rule sets to fit your organization’s specific needs. Because it’s an open-source IDS/IPS, Suricata benefits from a large, active community that constantly develops and refines its capabilities.

Put simply, Suricata is a powerful and adaptable tool that provides a robust layer of defense for any organization’s network security strategy.

Why use NIDS?

Here are some compelling reasons to use Network Intrusion Detection Systems (NIDS):

• Enhanced Network Security: NIDS acts as a vigilant security guard, continuously monitoring network traffic for suspicious activity. They can detect a wide range of threats, including malware attempts, port scans, denial-of-service attacks, and attempts to exploit network vulnerabilities. By identifying these threats early on, NIDS provides valuable time for security personnel to investigate and respond before attackers can inflict significant damage.
• Improved Threat Visibility: NIDS offers a broader view of security threats across your network. They provide insights into network traffic patterns, helping you identify potential vulnerabilities and malicious activity targeting your network infrastructure. This increased visibility allows you to proactively address security weaknesses and strengthen your overall network defense posture.
• Early Warning System: NIDS functions as an early warning system, alerting you to potential intrusions before they can escalate into major security incidents. This allows you to take timely action to contain threats, minimize potential damage, and prevent attackers from achieving their objectives.
• Compliance with Regulations: Many industries and regulations mandate organizations to implement security measures for data protection. NIDS can play a crucial role in demonstrating compliance with these regulations by providing audit trails and logs of detected security events.
• Defense-in-Depth Approach: NIDS is a vital component of a layered security defense strategy. They work alongside other security measures like firewalls and access controls to provide an additional layer of intrusion detection and threat analysis. This layered approach strengthens your overall security posture and makes it more difficult for attackers to gain access to your systems.
• Reduced Risk of Data Breaches: By proactively identifying and containing intrusions, NIDS can significantly reduce the risk of data breaches. Early detection allows you to isolate compromised systems and prevent attackers from exfiltrating sensitive data.

Explore a modern alternative

Legacy IDS produces too many alerts with too many false positives, provides limited threat detection that lacks sufficient attack visibility into anomalous activity and more subtle attack signals and doesn’t include important contextual evidence needed to inform impact assessment and response. Traditional IDS vendors have failed to innovate in ways that solve these challenges, leading to inefficient or downright ineffective threat detection.

You need a network security platform that doesn’t generate an endless stream of useless alerts across part of your network, and instead automatically identifies alerts of interest and notifies you of only serious and imminent threats. Your organization deserves response-ready detection with visibility into your entire network regardless of the environment with easy access to all the contextual evidence you need to stop an attack before it can cause damage. Replace your legacy IDS with a modern network detection and response platform that gives you these features and more.

Clear NDR™ - Enterprise (formerly Stamus Security Platform™) is a network-based threat detection and response solution that eliminates the challenges of legacy IDS while lowering your response time. Clear - NDR harnesses the full potential of your network, bringing state-of-the-art threat detection, automated event triage, and unparalleled visibility to the security team.

Book a demo to see if Clear NDR is right for your organization.