What is an Intrusion Detection System (IDS)?

Network intrusion detection system

An intrusion detection system (IDS) is a software application or device that monitors a network for policy violations or malicious activity. These threats or violations are either collected centrally or reported using a security information and event management system. Some IDS respond to detected intrusion upon discovery, known as intrusion prevention systems (IPS). Other IDS require an incident responder or analyst to investigate an issue then take the appropriate steps to remediate the threat

Protecting your data from cybercriminals with the right IDS is fundamentally important – choose the type that’s right for you. Let’s take a closer look. 

How Does an IDS Work? 

An IDS monitors network traffic for malicious activity and sends alerts as soon as it is discovered. As mentioned above, it utilises software that checks a system or network for malicious activity or policy violations. IDS protects a computer network from unauthorised user access, sometimes insiders. The intrusion detector learning task builds a predictive model capable of distinguishing between ‘good connections’ and ‘bad connections’. 

The way in which an IDS works can be broken down into the following five steps: 

  1. An IDS monitors traffic on a network or system to detect suspicious activity. 
  1. It analyses the data flowing through a network to look for signs and patterns of abnormal behaviour. 
  1. An IDS compares network activity to a set of predefined patterns and rules to identify an intrusion or attack. 
  1. Once an IDS detects something that matches one of these patterns or rules, it will send an alert to the system administrator. 
  1. The system administrator investigates the alert immediately and takes action to prevent further intrusion or damage.  

How does an IDS differ from a firewall? 

An IDS does not provide overall protection to a network or endpoint. Whereas a firewall acts as a protective system. A firewall works differently by performing an analysis of the metadata of network packets and then either blocks or allows traffic based upon predefined rules. 

How to Choose the Right Type of IDS for Your Business 

Choosing the right IDS is the key to a secure business network. Organisations today rely heavily on computers for storing and managing their sensitive information and intra and inter-organisational communications. Businesses tend to utilise IDS that are provided by Security as a Service (SECaaS) companies, but it is extremely important to choose an IDS that meets the specific needs of your organisation. 

Types of IDS

Let’s take a closer look at the different types of IDS to determine which is best for your organisation. 

Network Intrusion Detection System  

Network intrusion detection systems (NIDS) are set up at designated points within a network to examine traffic from all devices connected to the network. It performs an observation of traffic on the entire subnet and matches the traffic to a collection of known attacks. Once abnormal behaviour is observed or an attack is identified, the alert will be sent to a system administrator. A good example of where NIDS is used best is by installing it onto the subnet where firewalls are situated to see if a malicious actor is trying to break through the firewall. 

Network Node Intrusion Detection System   

A network node intrusion detection system (NNIDS) is extremely similar to the above-mentioned NIDS. However, there is one major difference in that it is only applied to one host at a time instead of the entire subnet. The system checks each node connected to your network for both malicious activity and potential threats.  

Host Intrusion Detection System 

Host intrusion detection system (HIDS) run on independent devices or hosts on a network. HIDS monitor incoming and outgoing packets from a device only and will alert the system administrator if malicious or suspicious activity is detected. It works by taking a snapshot of existing system files and comparing it to the previous snapshot. If the analytical system files are deleted or even edited, an alert will be sent to the system administrator to investigate.  

Protocol-Based Intrusion Detection System 

Protocol-based intrusion detection systems (PIDS) comprise an agent or system that would reside at the frontend of a server, interpreting and controlling the protocol between a device and the server. By monitoring the HTTPS protocol stream and accepting the related HTTP protocol, it is trying to secure the web server.  

Application Protocol-Based Intrusion Detection System 

An application protocol-based intrusion detection system (APIDS) is an agent or system that resides within a group of servers. It identifies an intrusion by monitoring and interpreting the communication on application-specific protocols.  

Network-Based vs. Host-Based IDS 

A network-based IDS is designed to monitor network traffic while a host-based IDS monitors both computers and network traffic. NIDS can only monitor events local to a host while HIDS can detect attacks that cannot be seen. HIDS can operate successfully where network traffic is encrypted. HIDS are unaffected by switched networks. 

Intrusion Prevention System (IPS) vs. IDS 

An IPS takes action by itself to block an attempted intrusion or remediate an incident. An IDS is only designed to provide an alert about a potential incident, which enables a security analyst to investigate the event and determine whether there is any further action required. 

The Benefits of Using an IDS for Network Security 

There are a number of benefits to using intrusion detection system monitoring for network security. Let’s take a closer look at the top four pluses to utilising an IDS within your organisation: 

Detects malicious activity 

An IDS is able to detect suspicious activity and alert the system administrator before any significant damage is done. 

Improves network performance 

An IDS is able to identify any performance issues on a network. This comes in very handy when looking at improving network performance. 

Compliance needs 

An IDS will help your organisation meet its compliance requirements by generating reports and monitoring network activity. 

Provides insights 

An IDS generates key insights into network traffic. These can be used to identify weaknesses and improve overall network security. 

Can an IDS help identify insider threats? 

HIDS is highly effective against insider threats because it looks for unexpected changes, such as deletion, overwriting, and access to certain ports. Alerts are sent to system administrators to investigate activities that seem suspicious. 

IDS Best Practices: How to Configure and Maintain Your System 

Maintaining and securing IDS components is fundamentally important because they tend to be targeted by malicious actors who try to prevent the IDS from detecting attacks or want to gain access to sensitive information within the IDS, such as known configurations and host configurations.  

An IDS comprises several types of components, including agents or sensors, database servers, management servers, management networks, and user and administrator consoles. All applications and components’ operating systems should be kept up-to-date, and all software-based IDS components should be strengthened against threats. The following protective actions should always be considered: 

  • Keep all applications and operating systems up to date with the latest versions 
  • Create separate accounts for each IDS administrator and user 
  • Restrict network access to IDS components 
  • Ensure IDS management communications are adequately protected 
  • Back up configuration settings on a regular basis but ensure existing settings remain before applying updates. 

What are some common challenges with implementing an IDS? 

Besides the obvious evasion techniques, IDS technology is prone to false alarms or even the lack of any alarm. But the main weaknesses are false negatives or false positives. 

How RiskXchange can help you 

RiskXchange uses intrusion detection system (IDS) methods way above and beyond traditional intrusion detection systems which tend to use less advanced firewalls. RiskXchange provides a complete 360-degree view of your attack surface and enhances network security by providing a continuous 24/7 assessment of your attack surface in real time.