Required as No single defense is foolproof and attackers often exploit gaps between systems. The layers help delay, detect, and mitigate threats, while also aligning with best practices from NIST, ISO 27001, CIS, etc.

Physical Security

• Biometric access controls
• Security guards, CCTV
• Locked server rooms

• Environmental controls (fire suppression, cooling)

Network Security

• Firewalls (e.g., pfSense, Cisco ASA)
• Intrusion Detection/Prevention Systems (IDS/IPS)
• Network segmentation (VLANs, DMZ)

• VPNs and secure tunneling

Endpoint Security

• Antivirus / EDR solutions (e.g., CrowdStrike, SentinelOne)
• Device encryption (BitLocker, FileVault)
• USB and device control policies

• Mobile Device Management (MDM)

Application Security

• Input validation, output encoding
• Secure coding practices (OWASP Top 10)
• Web Application Firewalls (WAF)

• Regular code audits and penetration testing

Data Security

• Encryption (AES-256, TLS)
• Data Loss Prevention (DLP)
• Access controls and data classification

• Secure backups and disaster recovery

Identity & Access Management (IAM)

• Strong authentication (MFA, biometrics)
• Least privilege principle
• Role-Based Access Control (RBAC)

• Identity federation (e.g., SSO, SAML, OAuth)

Security Awareness & Human Layer

• Phishing simulation and training
• Security policies and acceptable use policies
• Regular training and refreshers

• Insider threat detection programs

Cloud Security (if using cloud infrastructure)

• IAM configuration
• Encryption of cloud storage

• Misconfiguration monitoring (e.g., AWS Config, Azure Defender)

Compliance & Monitoring Layer

• SIEM systems (Splunk, QRadar)
• Continuous compliance checks (CIS Benchmarks, NIST, PCI-DSS)
• Centralized logging and alerting

• Audit trails

• Zero Trust Architecture – trust nothing, verify everything.
• Regular patching and updates
• Security by design – build security into systems from the start.
• Continuous monitoring and threat hunting

• Incident response planning – test regularly