SIEM vs. IDS: Key Differences and Using Them Together

What Is Security Information and Event Management (SIEM)? 

Security Information and Event Management (SIEM) is a cybersecurity solution that collects and aggregates log data from various sources within an organization’s IT infrastructure, including networks, devices, and applications. This data is then analyzed to identify abnormal patterns or potential security threats, aiding in real-time security monitoring and incident response.

SIEM solutions are designed to provide a holistic view of an organization’s information security. They leverage data analytics, event correlation, and aggregation techniques to provide insight into security incidents, enabling IT teams to detect, investigate, and respond to cybersecurity threats. SIEM systems typically include dashboards, alerting mechanisms, and reporting tools to support compliance and security governance.

What Is an Intrusion Detection System (IDS)? 

An Intrusion Detection System (IDS) is a device or software application specifically designed to monitor network or system activities for malicious activities or policy violations. Once detected, the activity or violation is reported to an administrator or collected centrally using a SIEM system.

IDS technology plays a crucial role in a cybersecurity defense strategy, providing real-time analysis of network traffic or system configuration to detect potential vulnerabilities or intrusions. By analyzing patterns and comparing them against a database of known threats, IDS can identify suspicious activities, such as malware infections, unauthorized system access, or other security policy breaches, facilitating timely intervention and mitigation.

Understanding Related Security Systems: IPS and HIPS 

What is an Intrusion Protection System (IPS)?

An Intrusion Protection System (IPS) is a network security technology designed to detect and prevent identified threats in real-time. IPS often complements an Intrusion Detection System (IDS), which detects and alerts on potential security breaches; IPS can automatically take action to block or mitigate the threat without human intervention.

IPS operates by inspecting network traffic and looking for suspicious activity or patterns based on a set of predefined security rules or signatures. When a potential threat is detected, the IPS can take various actions, such as blocking traffic from a malicious IP address, dropping harmful packets, or closing affected network connections. Additionally, IPS systems are often integrated with other security technologies, including firewalls and SIEM systems, to provide a layered defense.

What is Host-Based Intrusion Detection/Protection (HIPS)?

Host-Based Intrusion Detection/Protection Systems (HIPS) are security solutions designed to monitor and protect individual hosts or computers from malicious activities and vulnerabilities. Unlike network-based systems that protect at the perimeter, HIPS provides security at the host level, offering deep visibility into the activities occurring on the host itself, including system calls, file system access, and network traffic.

HIPS combines the capabilities of intrusion detection and prevention, enabling it to not only detect suspicious activity but also take proactive measures to block or mitigate threats. This dual functionality is achieved through the use of various detection techniques, such as anomaly detection, behavioral analysis, and signature-based detection. By operating on the host itself, HIPS can offer protection against threats that may bypass perimeter defenses.

Tips from the expert

Steve Moore is Vice President and Chief Security Strategist at Exabeam, helping drive solutions for threat detection and advising customers on security programs and breach response. He is the host of the “The New CISO Podcast,” a Forbes Tech Council member, and Co-founder of TEN18 at Exabeam.

In my experience, here are actionable tips for integrating SIEM, IDS/IPS, and other security tools into a robust cybersecurity strategy:

Integrate threat intelligence into IDS and SIEM rules
Feed real-time threat intelligence (e.g., IoCs) into both IDS signatures and SIEM correlation rules. This ensures detection of the latest threats at both the network and broader security levels.

Prioritize IDS tuning based on critical assets
Begin with tuning IDS rules for high-value network segments or hosts. This ensures detailed monitoring where it matters most while reducing false positives from less critical areas.

Leverage SOAR for IDS-driven automation
Integrate IDS alerts with a SOAR platform to automate containment actions, such as isolating compromised systems or blocking suspicious IPs, ensuring rapid response with minimal manual intervention.

Correlate IDS data with SIEM UEBA for advanced insights
Use SIEM’s User and Entity Behavior Analytics (UEBA) to analyze IDS alerts. This helps identify insider threats or advanced persistent threats (APTs) by linking packet-level data to anomalous user or device behaviors.

Deploy HIPS for granular host-level detection
Use Host-Based Intrusion Detection/Protection Systems (HIPS) to complement network-focused IDS. HIPS provides deep visibility into endpoint activities, filling gaps where IDS may miss threats.

SIEM vs. IDS: Integration, Scope, and Function 

SIEM systems provide a comprehensive view of an organization’s security status by aggregating and analyzing data from various sources, including IDS. This allows SIEM to offer insights into a broader scope of security events, making it useful for incident response and compliance reporting. 

IDS focuses on monitoring and reporting specific types of malicious activities and policy violations within network traffic or on host systems. While IDS is essential for immediate threat detection, SIEM leverages the data from IDS and other sources for a more holistic analysis.

The primary function of an IDS is to detect unauthorized access or attacks on a network or system. It operates by analyzing traffic or system behavior for known threats and anomalies, alerting security personnel to potential issues. SIEM, on the other hand, not only collects and analyzes data from IDS but also from firewalls, antivirus tools, and other security technologies. This allows SIEM to identify complex threat patterns and coordinate an effective response.

SIEM vs. IDS: How Do They Support Response and Mitigation? 

IPS Integrates with Firewalls/Access Control Systems

Intrusion Protection Systems (IPS) integrate with firewalls and access control systems to enhance the security posture of an organization’s network. By working in conjunction with firewalls, which serve as the first line of defense by controlling incoming and outgoing network traffic based on predetermined security rules, IPS adds an additional layer of security.

When integrated, IPS can analyze the traffic allowed through by the firewall in real time, identifying and mitigating threats before they reach the network’s internal resources. This not only improves the detection of sophisticated attacks that may pass through firewall rules but also enables automated response actions, such as blocking malicious traffic or quarantining infected systems.

SIEM integrates SOAR

SIEM systems commonly integrate with Security Orchestration, Automation, and Response (SOAR) platforms. While SIEM provides visibility into security events across the organization, SOAR enhances these capabilities by automating workflows and response actions.

The integration of SIEM with SOAR allows for the automated gathering of threat intelligence and execution of predefined response protocols to security incidents, significantly reducing response times. SOAR enables security teams to implement complex workflows that can automatically prioritize incidents based on severity, gather contextual information, and execute response actions such as isolating infected endpoints or blocking IP addresses.

SIEM vs. IDS: Complexity and Resource Requirements

IDS is Easy to Configure But Challenging to Tune

Intrusion Detection Systems (IDS) are relatively straightforward to set up, making them accessible for organizations of various sizes to implement as part of their cybersecurity defenses. Initial configuration typically involves defining the network segments to monitor and applying pre-configured detection rules or signatures. However, the challenge with IDS lies in its ongoing tuning to balance sensitivity and specificity.

Tuning involves adjusting the system to minimize false positives (benign activities flagged as threats) and false negatives (actual threats missed by the system). This requires a deep understanding of the network’s normal traffic patterns, the organization’s security policies, and the evolving threat landscape. Effective tuning is critical for ensuring that IDS remains an efficient tool for detecting genuine threats without causing alert fatigue.

SIEM is Harder to Configure But Easier to Tune

Setting up a Security Information and Event Management (SIEM) system is inherently more complex than configuring an IDS because it involves integrating multiple data sources and configuring rules for event correlation, analysis, and alerting. The complexity arises from the need to understand the data formats and security logs generated by different systems, such as firewalls, IDS, antivirus solutions, and various other network and security devices.

Despite its initial complexity, SIEM systems are generally easier to tune compared to IDS. Once the system is up and running, SIEM’s advanced analytics and correlation capabilities allow for more precise adjustments based on the organization’s specific security requirements and threat environment. Tuning a SIEM involves refining the correlation rules and analytics to improve accuracy in identifying real threats and reducing false positives.

Choosing Between SIEM and IDS/IPS 

Core Need: Protecting a Closed Network or Distributed Environment

When deciding between SIEM and IDS/IPS for your organization, the core network environment plays a crucial role. For closed networks, where all devices and users operate within a controlled physical and network perimeter, IDS/IPS solutions might be sufficient to monitor and protect against internal and perimeter threats. These systems can effectively detect unauthorized access attempts and prevent intrusions in environments where network traffic is more predictable and contained.

In contrast, distributed environments, characterized by remote locations, cloud services, and mobile access, require a more comprehensive approach to security. SIEM solutions are better suited for these environments due to their ability to aggregate and analyze data from a wide variety of sources across different locations. SIEM’s centralized monitoring and analysis provide insights into complex threat patterns that span across cloud, on-premises, and remote infrastructure.

Existing Security Infrastructure, Resources, Locations, and Capabilities

The choice between SIEM and IDS/IPS also depends on the organization’s existing security infrastructure, resources, physical locations, and technical capabilities. Organizations with limited IT security resources might lean towards IDS/IPS for its simpler setup and lower maintenance compared to SIEM. However, for businesses with multiple locations, including cloud-based assets, and the capability to manage complex systems, SIEM offers a more integrated and comprehensive view of security events.

Organizations should also consider their technical staff’s expertise and the ability to manage and tune complex security systems. While IDS/IPS can be relatively straightforward to deploy and manage, SIEM systems require a higher level of expertise due to their complexity and the need for ongoing tuning to accurately correlate and analyze security data from disparate sources.

Specific Security Needs and Compliance Requirements

Specific security needs and compliance requirements are significant factors in choosing between SIEM and IDS/IPS. If the primary concern is to meet specific regulatory compliance that mandates real-time analysis, incident detection, and reporting across all network and system activities, a SIEM solution is indispensable. SIEM systems can provide the comprehensive logging, monitoring, and reporting capabilities required to comply with standards such as GDPR, HIPAA, SOX, and PCI-DSS.

For organizations focused on detecting and preventing unauthorized access and threats to their network infrastructure without compliance-driven requirements, IDS/IPS may be sufficient. These systems can effectively identify and block potential security threats at the network or host level, providing a focused approach to intrusion detection and prevention.

How SIEM and IDS Work Together 

IDS Events Enhance SIEM Detection

Integrating IDS with SIEM systems enhances the overall security monitoring and threat detection capabilities of an organization. IDS can feed detailed event logs and alerts about potential security incidents directly into the SIEM system. This integration allows SIEM to leverage IDS’s detailed, packet-level analysis, enriching the SIEM’s broader dataset with specific detection events.

IDS Events Trigger Automation

The combination of IDS and SIEM can significantly improve incident response times through automation. IDS detections can trigger automated workflows within the SIEM, such as alerts, incident ticket creation, or even direct responses like blocking IP addresses or isolating affected systems. This automated response capability ensures that potential threats are addressed swiftly, reducing the window of opportunity for attackers and minimizing the impact of security incidents.

IDS Packet-Level Inspection Improves SIEM Confidence

The packet-level inspection capabilities of IDS provide a high level of detail about network traffic and potential threats. When this data is integrated into SIEM systems, it significantly enhances the confidence in threat detection and analysis. SIEM can use this detailed information to better understand complex attacks, reduce false positives, and more accurately identify genuine threats.

Exabeam Platform Capabilities: SIEM, UEBA, SOAR, Insider Threats, Compliance, TDIR

The Exabeam Security Operations Platform applies AI and automation to security operations workflows for a holistic approach to combating cyberthreats, delivering the most effective threat detection, investigation, and response (TDIR): 

• AI-driven detections pinpoint high-risk threats by learning normal behavior of users and entities, and prioritizing threats with context-aware risk scoring. 
• Automated investigations simplify security operations, correlating disparate data to create threat timelines. 
• Playbooks document workflows and standardize activity to speed investigation and response. 
• Visualizations map coverage against the most strategic outcomes and frameworks to close data and detection gaps. 

With these capabilities, Exabeam empowers security operations teams to achieve faster, more accurate, and consistent TDIR.