IDS VS SIEM: Essential Guide to OT Security

Companies can use a couple of security tools to enhance IIoT security. These tools are crucial in protecting critical systems from malware, ransomware, viruses, and more. Two important examples of these tools are Intrusion Detection Systems (IDS) and Security Information and Event Management (SIEM). Often, in comparing critical security tools, an IDS vs SIEM vs IPS comparison is made, but in dealing with each comparison appropriately, we’ll be examining IDS vs SIEM today.

What Is an Intrusion Detection System (IDS)

Intrusion detection systems are cybersecurity tools that alert a central control system or IT security team member of any malicious or suspicious activity on a network. It is vital to note that IDS does not act to remove the threat. Its key duty is to alert the appropriate designated personnel or system of intrusion. IDS is a first-stage security tool that works with other tools to ensure complete CPS security.

What is SIEM?

Initially, security information and event management tools were simply log management solutions that merged security information management (SIM) and security event management (SEM) functions and took stock of various security logs. With time, SIEM has evolved into a more holistic security tool using user and entity behavior analytics (UEBA), AI, machine learning, and other advanced systems to identify threats before they occur and help security teams respond to security threats before they occur.

In various IDS vs SIEM vs IPS comparisons, the general conclusion is that these systems work together effectively, as they share some features in common, such as detection tools rather than threat elimination tools. It is also consensus that their differences also make them complementary tools in the cybersecurity process.

Differences Between IDS and SIEM

There are a couple of differences that set IDS and SIEM apart; they include:

Major functions

On the surface, both tools seem to inform appropriate elimination systems, like an IPS of threats, but they have key functional differences.

• IDS: An IDS has a key task of monitoring network traffic. Through this means, it can identify suspicious activities going through a network.
  
• SIEM: SIEMs, on the other hand, monitor, collect, and analyze security-related data across multiple sources. The collected information is then used to identify potential security threats.

Mode of operation

While both tools collect data, their approach to data collection differs.

• IDS: The exclusive methods IDS uses to identify known threats are signature matching and rule-based detection.
  
• SIEM: Regarding security information and event management (SIEM), advanced analytics like correlation, anomaly detection, and analysis utilizing machine learning models are used to spot potential dangers.
  

Alert type

Both tools provide alerts for IT experts to work with, but the type of alerts they give differs.

• IDS: IDS is primarily a notification security tool, but its alerts often require further investigation before being acted upon.
  
• SIEM: On the other hand, SIEM delivers real-time alerts that are actionable right off the bat.

Data storage

IDS and SIEM have different storage capacities.

• IDS: IDS solutions generally have limited storage capacities; while this is a disadvantage, they are suitable short-term security tools.
  
• SIEM: Because of the amount of data they work with, SIEMs are often designed with large storage capacity.

Data storage

Both solutions require data sources to be analyzed for possible threats and suspicious activities to function effectively.

• IDS: IDS has one primary data source: the network traffic in which it functions. Depending on its mode of operation, it could also get its data from its existing collection of signatures.
  
• SIEM: On the other hand, SIEMs collect data from various sources, including working IDS tools, firewalls, SIEM tools, and other security tools within a working system.

Compliance

Compliance with national and international standards is vital in securing cyber-physical systems.

• IDS: Compliance is not the end goal behind most IDS designs, but they often meet some compliance standards.
  
• SIEM: SIEMs are usually designed to meet compliance requirements. They do this by providing companies with centralized log collection, analysis, and reporting systems.
  

The Challenges of Using IDS and SIEM Systems

There are a few common key challenges between IDS and SIEMs.

1. Data Overload and Alert Fatigue:
   When they identify a threat or detect a threat in a network packet, both IDS and SIEM systems generate numerous alerts. These alerts often include false positives, like a new authorized user gaining access to a secure network for the first time. Repetitive false positives can make IT personnel numb to the alerts making them miss actual threats.
2. Lack of Operational Context in IT/OT Environments:
   Industrial systems mix machinery, sensors, and control systems with IT infrastructure. Designed for IT contexts, IDS and SIEM solutions might lack the background to separate normal operating variations from malicious activities. Without this knowledge, security teams can miss minor indicators of an attack or misread mechanical processes as threats.
3. Reactive, Post-Incident Response:
   While IDS and SIEM systems can identify abnormal behavior, their design occasionally delays security teams’ reactions to events. Post-incident reactions could compromise the ability of a company to foresee and minimize risks. In sectors where downtime and interruptions are expensive, waiting until danger strikes is a disadvantage; proactive and predictive threat management becomes even more critical.

The Cost and Complexity of IDS and SIEM Solutions

IDS are more straightforward in execution and their entire process when compared with SIEM. Intrusion detection systems (IDS) can be deployed at a network’s partition to monitor its traffic and send alerts of intrusions, but SIEMs run a bit more complex systems. SIEMs are more complex as they parse a lot more information and have to make predictive decisions on potential threats. This makes them more costly compared to IDS.  

IDS Pros and Cons

Pros of IDS:

• IDS can be trained to address specific malicious content within a network packet.
• IDS can identify the types of attacks and the number of times attacks have occurred over a given network.
• IDS excels in real-time monitoring, making it a vital first-line defense against malicious activity. 
• IDS can look at data in the context of the protocol.
• IDS’s straightforward design makes it cost-effective and relatively simple to implement.

Cons of IDS:

• IDS only detects and alerts but does not act to neutralize threats. 
• IDS is unable to process encrypted data packets.
• IDS can generate false positives, leading to unnecessary alerts and potential resource inefficiencies.

SIEM Pros and Cons

Pros of SIEM:

• SIEM helps with regulatory compliance, allowing OT businesses to align with global safety standards.
• SIEM shortens the time it takes to detect and identify threats, allowing you to react faster. 
• SIEM offers a more comprehensive approach, integrating advanced analytics, AI, and machine learning to proactively identify and prioritize threats. 
• SIEM’s predictive capabilities and real-time insights help organizations avoid potential attacks, reducing downtime and operational disruptions.
• SIEM provides accurate logs that are useful for other industrial cybersecurity applications. 

Cons of IDS:

• SIEM tools can be resource-intensive, requiring significant investment in setup, maintenance, and skilled personnel for effective operation. 
• SIEM tools can be time-consuming to implement.
• SIEMs can be expensive.