IDS/IPS & SIEM Tools
1 Global Definition
An Intrusion Detection System (IDS) monitors networks or hosts to identify suspicious activity and raises alerts for security teams to investigate. An Intrusion Prevention System (IPS) provides active protection by automatically blocking or containing malicious traffic in real time before it can cause damage. A Security Information and Event Management (SIEM) platform serves as a central security operations center that collects, analyzes, and correlates security data from across the entire environment, enabling security teams to detect complex threats and maintain compliance with security standards.
1.1 IDS vs IPS
Intrusion Detection System (IDS)
Continuously monitors traffic or system activity and generates security alerts for investigation.
- NIDS — Monitors network communications
- HIDS — Protects individual servers and workstations
- Provides comprehensive visibility and supports forensic analysis
Intrusion Prevention System (IPS)
Deployed inline with network traffic to automatically block or quarantine malicious content.
- NIPS, HIPS
- Requires careful configuration to minimize false positives
- Essential for automatically stopping confirmed threats
1.2 Detection Methods
Signature-Based Detection
Identifies known threats by matching against established attack patterns.
- Fast and reliable for known malicious patterns
- Limited effectiveness against new or modified attacks
- Examples: Snort/Suricata rules
Anomaly-Based Detection
Identifies unusual behavior that deviates from established normal patterns.
- Effective for detecting previously unknown threats
- Requires establishing behavioral baselines and may generate more alerts
- Valuable for detecting internal threats
Behavioral Analysis
Focuses on attack sequences and methodologies rather than individual indicators.
- Detects multi-stage attacks and misuse of legitimate tools
- Often aligned with MITRE ATT&CK framework
Machine Learning & Analytics
Advanced analytics and UEBA detect sophisticated and slow-evolving threats.
- Excellent for identifying compromised accounts and insider risks
- Requires quality data and continuous refinement
1.3 Deployment & Architecture
Monitoring Access Points
- SPAN/Mirror Ports or Network TAPs for monitoring systems
- Inline Deployment for prevention systems
- Strategic placement at network boundaries and between internal segments
Optimization & Management
- Establish normal traffic patterns, reduce noise from legitimate activity
- Regularly update detection rules and analytical models
- Monitor Detection Accuracy and system performance
Security Data Management
- Network Capture for detailed investigation
- Forward security events to SIEM using Syslog, security agents, or integration APIs
- Synchronize time across systems with NTP
1.4 SIEM Overview
SIEM systems collect, standardize, enrich, and correlate security-related information from across the organization to generate actionable security insights and compliance reports.
Security Data Sources
- Network security devices, endpoint protection, servers, applications, cloud services, identity systems
- Asset management and vulnerability assessment data for context
Data Processing
- Convert diverse data into consistent security event format
- Enhance with threat intelligence, geographic data, asset importance, and user context
Security Correlation
- Pattern recognition across multiple events
- Mapping to security frameworks and attack lifecycles
- Risk-based prioritization and alert refinement
1.5 SIEM Capabilities
Security Operations
- Real-time dashboards and investigation tools
- Alert management with escalation and tracking
- Incident management and timeline analysis
Security Automation
- Security Orchestration playbooks
- Automated threat investigation and context gathering
- Automated containment measures for confirmed threats
Compliance & Reporting
- Secure data retention and protection
- Pre-built compliance reports for security standards
- Role-based access control and audit trails
1.6 Benefits & Challenges
Security Advantages
- Early threat identification and automated protection
- Unified security visibility and accelerated investigation
- Support for risk management and regulatory compliance
Implementation Considerations
- Limited visibility into encrypted communications
- Alert management and system tuning requirements
- Infrastructure requirements for comprehensive monitoring
1.7 Real-World Workflow
- Monitoring system detects unusual network activity → Security alert generated
- SIEM correlates multiple security events and threat intelligence matches
- Automated investigation gathers additional context and escalates priority
- Security analyst confirms threat → Protective measures activated and affected systems secured
- Post-incident review: Enhance detection capabilities, update security baselines, generate compliance documentation
1.8 Why IDS/IPS & SIEM Matter
IDS/IPS systems provide essential threat detection and automated protection capabilities, while SIEM platforms deliver comprehensive security visibility and intelligence for effective incident response and compliance management. Together, these technologies form the foundation of modern security operations, providing the monitoring, analysis, and protection needed to defend today's complex digital environments.