⚙️ What is Threat Detection?

Definition:

Threat detection is the process of identifying malicious activity or security breaches in a system or network.

Goal:

• Detect attacks early
• Respond quickly to prevent damage
• Maintain confidentiality, integrity, and availability

---

1️⃣ SIEM (Security Information and Event Management)

Definition:

SIEM collects, aggregates, and analyzes logs and events from multiple sources to detect suspicious patterns.

Key Functions:

1. Log collection → from servers, network devices, firewalls, apps
2. Correlation → detect patterns across systems
3. Alerting → notify security team about potential threats
4. Reporting & compliance → audit trails, regulatory compliance

Examples:

• Splunk, IBM QRadar, ArcSight, Azure Sentinel

Pros:

• Centralized view of security events
• Can detect complex multi-step attacks

Cons:

• Reactive; relies on logs
• Requires tuning to reduce false positives

---

2️⃣ IDS (Intrusion Detection System)

Definition:

IDS monitors network or host activity to detect suspicious behavior or policy violations, but does not block traffic.

Types:

1. Network IDS (NIDS) → monitors network traffic
2. Host IDS (HIDS) → monitors individual systems

Detection Methods:

• Signature-based: match known attack patterns
• Anomaly-based: detect deviations from normal behavior

Pros:

• Detects attacks in real-time
• Can provide alerts for forensic analysis

Cons:

• Cannot prevent attacks (alert only)
• Signature-based IDS cannot detect unknown attacks

Examples:

• Snort, Suricata, OSSEC

---

3️⃣ IPS (Intrusion Prevention System)

Definition:

IPS is similar to IDS but can actively block malicious traffic instead of just alerting.

Functions:

• Detect malicious activity (like IDS)
• Drop packets or terminate connections
• Protect networks automatically

Pros:

• Real-time prevention of attacks
• Reduces workload on security team

Cons:

• False positives can block legitimate traffic
• Needs careful configuration

Examples:

• Cisco Firepower, Palo Alto Threat Prevention

---

🔄 Comparison Table

Feature	SIEM	IDS	IPS
Purpose	Analyze logs/events	Detect intrusions	Detect & prevent intrusions
Action	Alert/report	Alert	Block / prevent
Data Source	Logs from multiple sources	Network/Host traffic	Network/Host traffic
Detection	Correlation & patterns	Signatures/Anomalies	Signatures/Anomalies
Real-time	Usually near real-time	Real-time	Real-time

---

🧩 Analogy

• SIEM: Security dashboard → collects CCTV footage and alarms, analyzes patterns
• IDS: Security guard → notices suspicious behavior and calls the team
• IPS: Security guard + automatic lock → notices suspicious behavior and blocks entry immediately

---

✅ Key Takeaways

1. Threat detection = identify malicious activity early
2. SIEM → centralizes logs, correlates events, alerts
3. IDS → detects intrusions, alerts only
4. IPS → detects intrusions, actively blocks them
5. For robust security → often used together: SIEM + IDS/IPS

---