Defense in Depth

Defense in Depth (also “Layered Security” or “Multi-Layer Defense”) is a security strategy that implements multiple layers of protection controls to create redundancy and resilience, ensuring that if one layer fails, the others continue to protect assets. This strategy combines physical, technical, and administrative controls at different levels of infrastructure, applications, and processes, being fundamental for protecting against advanced persistent threats (APT), reducing attack surface, and improving overall organizational security posture.

What is Defense in Depth?

Defense in Depth is a security approach that recognizes that no individual control is perfect and that threats can evolve, so it implements multiple layers of defense to create a robust and resilient system.

Fundamental Principles

Multiple Layers of Protection

  • Redundancy: Multiple controls for the same threat
  • Diversity: Different types of controls
  • Depth: Multiple levels of defense
  • Coverage: Complete perimeter protection

Fail Secure

  • Fail Closed: If it fails, blocks by default
  • Gradual Degradation: Gradual loss of functionality
  • Recovery: Automatic recovery capability
  • Monitoring: Failure detection

Intelligent Redundancy

  • Complementary Controls: Controls that reinforce each other
  • Early Detection: Detection at multiple points
  • Coordinated Response: Coordinated response between layers
  • Learning: Improvement based on incidents

Defense in Depth Layers

Layer 1: Policies and Procedures

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class PolicyLayer:
    def __init__(self):
        self.policies = {}
        self.procedures = {}
        self.compliance_frameworks = {
            'ISO_27001': {'coverage': 0.9, 'maturity': 'high'},
            'NIST': {'coverage': 0.8, 'maturity': 'medium'},
            'COBIT': {'coverage': 0.7, 'maturity': 'medium'}
        }
    
    def create_policy(self, policy_id, policy_config):
        """Create security policy"""
        self.policies[policy_id] = {
            'policy_id': policy_id,
            'name': policy_config['name'],
            'category': policy_config['category'],
            'scope': policy_config['scope'],
            'requirements': policy_config.get('requirements', []),
            'enforcement_level': policy_config.get('enforcement_level', 'mandatory'),
            'review_frequency': policy_config.get('review_frequency', 'annual'),
            'last_review': None,
            'next_review': None,
            'compliance_status': 'pending'
        }
    
    def create_procedure(self, procedure_id, procedure_config):
        """Create security procedure"""
        self.procedures[procedure_id] = {
            'procedure_id': procedure_id,
            'name': procedure_config['name'],
            'policy_id': procedure_config['policy_id'],
            'steps': procedure_config.get('steps', []),
            'responsible_role': procedure_config.get('responsible_role', 'Security_Team'),
            'frequency': procedure_config.get('frequency', 'as_needed'),
            'automation_level': procedure_config.get('automation_level', 'manual'),
            'success_metrics': procedure_config.get('success_metrics', [])
        }
    
    def assess_policy_coverage(self):
        """Assess policy coverage"""
        coverage_areas = {
            'access_control': 0,
            'data_protection': 0,
            'incident_response': 0,
            'business_continuity': 0,
            'compliance': 0
        }
        
        for policy in self.policies.values():
            category = policy['category']
            if category in coverage_areas:
                coverage_areas[category] += 1
        
        total_policies = len(self.policies)
        coverage_percentage = {
            area: (count / total_policies * 100) if total_policies > 0 else 0
            for area, count in coverage_areas.items()
        }
        
        return coverage_percentage
    
    def get_policy_effectiveness(self, policy_id):
        """Get policy effectiveness"""
        if policy_id not in self.policies:
            return None
        
        policy = self.policies[policy_id]
        
        # Effectiveness factors
        factors = {
            'clarity': 0.8,  # Policy clarity
            'enforcement': 0.7,  # Compliance level
            'awareness': 0.9,  # Staff knowledge
            'review_frequency': 0.6,  # Review frequency
            'compliance': 0.8  # Regulatory compliance
        }
        
        effectiveness = sum(factors.values()) / len(factors)
        
        return {
            'policy_id': policy_id,
            'effectiveness_score': effectiveness,
            'factors': factors,
            'recommendations': self.get_improvement_recommendations(factors)
        }
    
    def get_improvement_recommendations(self, factors):
        """Get improvement recommendations"""
        recommendations = []
        
        if factors['clarity'] < 0.8:
            recommendations.append('Improve policy clarity')
        if factors['enforcement'] < 0.8:
            recommendations.append('Increase compliance level')
        if factors['awareness'] < 0.8:
            recommendations.append('Improve staff training')
        if factors['review_frequency'] < 0.8:
            recommendations.append('Increase review frequency')
        if factors['compliance'] < 0.8:
            recommendations.append('Improve regulatory compliance')
        
        return recommendations

# Usage example
policy_layer = PolicyLayer()

# Create policies
policy_layer.create_policy('POL-001', {
    'name': 'Access Control Policy',
    'category': 'access_control',
    'scope': 'All users and systems',
    'requirements': ['Authentication', 'Authorization', 'Audit'],
    'enforcement_level': 'mandatory'
})

policy_layer.create_policy('POL-002', {
    'name': 'Data Protection Policy',
    'category': 'data_protection',
    'scope': 'All data assets',
    'requirements': ['Encryption', 'Classification', 'Retention'],
    'enforcement_level': 'mandatory'
})

# Assess coverage
coverage = policy_layer.assess_policy_coverage()
print(f"Policy coverage: {coverage}")

# Assess effectiveness
effectiveness = policy_layer.get_policy_effectiveness('POL-001')
print(f"Policy effectiveness: {effectiveness['effectiveness_score']:.2f}")

Layer 2: Physical Controls

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class PhysicalSecurityLayer:
    def __init__(self):
        self.physical_controls = {}
        self.access_points = {}
        self.monitoring_systems = {}
        self.environmental_controls = {}
    
    def install_physical_control(self, control_id, control_config):
        """Install physical control"""
        self.physical_controls[control_id] = {
            'control_id': control_id,
            'type': control_config['type'],
            'location': control_config['location'],
            'function': control_config['function'],
            'status': 'active',
            'last_maintenance': None,
            'next_maintenance': None,
            'effectiveness': 0.0
        }
    
    def create_access_point(self, point_id, point_config):
        """Create access point"""
        self.access_points[point_id] = {
            'point_id': point_id,
            'name': point_config['name'],
            'location': point_config['location'],
            'access_type': point_config['access_type'],
            'controls': point_config.get('controls', []),
            'monitoring': point_config.get('monitoring', True),
            'access_log': []
        }
    
    def log_access_attempt(self, point_id, user_id, access_type, timestamp, success):
        """Log access attempt"""
        if point_id in self.access_points:
            access_record = {
                'user_id': user_id,
                'access_type': access_type,
                'timestamp': timestamp,
                'success': success,
                'point_id': point_id
            }
            
            self.access_points[point_id]['access_log'].append(access_record)
    
    def assess_physical_security(self):
        """Assess physical security"""
        assessment = {
            'total_controls': len(self.physical_controls),
            'active_controls': len([c for c in self.physical_controls.values() if c['status'] == 'active']),
            'access_points': len(self.access_points),
            'monitored_points': len([p for p in self.access_points.values() if p['monitoring']]),
            'security_score': 0.0
        }
        
        # Calculate security score
        if assessment['total_controls'] > 0:
            control_effectiveness = sum(c['effectiveness'] for c in self.physical_controls.values()) / assessment['total_controls']
            monitoring_coverage = assessment['monitored_points'] / assessment['access_points'] if assessment['access_points'] > 0 else 0
            
            assessment['security_score'] = (control_effectiveness + monitoring_coverage) / 2
        
        return assessment
    
    def get_access_anomalies(self, point_id, time_window_hours=24):
        """Detect access anomalies"""
        if point_id not in self.access_points:
            return []
        
        access_log = self.access_points[point_id]['access_log']
        cutoff_time = datetime.now() - timedelta(hours=time_window_hours)
        
        recent_access = [record for record in access_log if record['timestamp'] >= cutoff_time]
        
        anomalies = []
        
        # Detect off-hours access
        off_hours_access = [r for r in recent_access if r['timestamp'].hour < 6 or r['timestamp'].hour > 22]
        if off_hours_access:
            anomalies.append({
                'type': 'off_hours_access',
                'count': len(off_hours_access),
                'description': 'Access outside normal hours'
            })
        
        # Detect multiple failed attempts
        failed_attempts = [r for r in recent_access if not r['success']]
        if len(failed_attempts) > 3:
            anomalies.append({
                'type': 'multiple_failed_attempts',
                'count': len(failed_attempts),
                'description': 'Multiple failed access attempts'
            })
        
        return anomalies

# Usage example
physical_layer = PhysicalSecurityLayer()

# Install physical controls
physical_layer.install_physical_control('CTRL-001', {
    'type': 'Biometric Scanner',
    'location': 'Main Entrance',
    'function': 'Access Control'
})

physical_layer.install_physical_control('CTRL-002', {
    'type': 'Security Camera',
    'location': 'Data Center',
    'function': 'Surveillance'
})

# Create access point
physical_layer.create_access_point('AP-001', {
    'name': 'Main Data Center Door',
    'location': 'Building A, Floor 1',
    'access_type': 'Card + Biometric',
    'controls': ['CTRL-001', 'CTRL-002'],
    'monitoring': True
})

# Assess physical security
assessment = physical_layer.assess_physical_security()
print(f"Physical security assessment: {assessment}")

Layer 3: Network Controls

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class NetworkSecurityLayer:
    def __init__(self):
        self.network_devices = {}
        self.security_zones = {}
        self.traffic_rules = {}
        self.intrusion_detection = {}
    
    def configure_firewall(self, firewall_id, config):
        """Configure firewall"""
        self.network_devices[firewall_id] = {
            'device_id': firewall_id,
            'type': 'firewall',
            'model': config['model'],
            'rules': config.get('rules', []),
            'zones': config.get('zones', []),
            'status': 'active',
            'last_update': None,
            'threat_intelligence': config.get('threat_intelligence', True)
        }
    
    def create_security_zone(self, zone_id, zone_config):
        """Create security zone"""
        self.security_zones[zone_id] = {
            'zone_id': zone_id,
            'name': zone_config['name'],
            'trust_level': zone_config['trust_level'],
            'subnets': zone_config.get('subnets', []),
            'allowed_protocols': zone_config.get('protocols', []),
            'allowed_ports': zone_config.get('ports', []),
            'isolation_level': zone_config.get('isolation_level', 'medium'),
            'monitoring': zone_config.get('monitoring', True)
        }
    
    def define_traffic_rule(self, rule_id, rule_config):
        """Define traffic rule"""
        self.traffic_rules[rule_id] = {
            'rule_id': rule_id,
            'name': rule_config['name'],
            'source_zone': rule_config['source_zone'],
            'destination_zone': rule_config['destination_zone'],
            'protocol': rule_config.get('protocol', 'any'),
            'port': rule_config.get('port', 'any'),
            'action': rule_config['action'],  # allow, deny, log
            'priority': rule_config.get('priority', 100),
            'enabled': rule_config.get('enabled', True)
        }
    
    def monitor_network_traffic(self, source_zone, destination_zone, protocol, port):
        """Monitor network traffic"""
        # Find applicable rule
        applicable_rules = []
        
        for rule in self.traffic_rules.values():
            if not rule['enabled']:
                continue
            
            if (rule['source_zone'] == source_zone and 
                rule['destination_zone'] == destination_zone and
                (rule['protocol'] == protocol or rule['protocol'] == 'any') and
                (rule['port'] == port or rule['port'] == 'any')):
                applicable_rules.append(rule)
        
        # Sort by priority (lower number = higher priority)
        applicable_rules.sort(key=lambda x: x['priority'])
        
        if applicable_rules:
            rule = applicable_rules[0]
            return {
                'action': rule['action'],
                'rule_id': rule['rule_id'],
                'rule_name': rule['name']
            }
        else:
            return {
                'action': 'deny',
                'rule_id': 'default',
                'rule_name': 'Default Deny'
            }
    
    def detect_intrusion(self, traffic_data):
        """Detect intrusions"""
        alerts = []
        
        # Detect suspicious patterns
        if traffic_data.get('packet_size') > 1500:  # Large packets
            alerts.append({
                'type': 'large_packet',
                'severity': 'medium',
                'description': 'Unusual size packet detected'
            })
        
        if traffic_data.get('connection_attempts') > 100:  # Many connection attempts
            alerts.append({
                'type': 'connection_flood',
                'severity': 'high',
                'description': 'Possible connection flood attack'
            })
        
        if traffic_data.get('port_scanning'):  # Port scanning
            alerts.append({
                'type': 'port_scan',
                'severity': 'high',
                'description': 'Port scan detected'
            })
        
        return alerts
    
    def get_network_security_status(self):
        """Get network security status"""
        status = {
            'total_devices': len(self.network_devices),
            'active_devices': len([d for d in self.network_devices.values() if d['status'] == 'active']),
            'security_zones': len(self.security_zones),
            'traffic_rules': len(self.traffic_rules),
            'enabled_rules': len([r for r in self.traffic_rules.values() if r['enabled']]),
            'security_score': 0.0
        }
        
        # Calculate security score
        if status['total_devices'] > 0 and status['traffic_rules'] > 0:
            device_ratio = status['active_devices'] / status['total_devices']
            rule_ratio = status['enabled_rules'] / status['traffic_rules']
            zone_coverage = status['security_zones'] / 5  # Assuming 5 ideal zones
            
            status['security_score'] = (device_ratio + rule_ratio + zone_coverage) / 3
        
        return status

# Usage example
network_layer = NetworkSecurityLayer()

# Configure firewall
network_layer.configure_firewall('FW-001', {
    'model': 'Cisco ASA',
    'zones': ['internal', 'dmz', 'external'],
    'threat_intelligence': True
})

# Create security zones
network_layer.create_security_zone('internal', {
    'name': 'Internal Network',
    'trust_level': 'high',
    'subnets': ['10.0.0.0/8'],
    'protocols': ['TCP', 'UDP', 'ICMP'],
    'isolation_level': 'low'
})

network_layer.create_security_zone('dmz', {
    'name': 'DMZ',
    'trust_level': 'medium',
    'subnets': ['192.168.1.0/24'],
    'protocols': ['TCP'],
    'isolation_level': 'high'
})

# Define traffic rules
network_layer.define_traffic_rule('RULE-001', {
    'name': 'Internal to DMZ HTTP',
    'source_zone': 'internal',
    'destination_zone': 'dmz',
    'protocol': 'TCP',
    'port': '80',
    'action': 'allow',
    'priority': 10
})

# Monitor traffic
traffic_result = network_layer.monitor_network_traffic('internal', 'dmz', 'TCP', '80')
print(f"Monitoring result: {traffic_result}")

# Get security status
security_status = network_layer.get_network_security_status()
print(f"Network security status: {security_status}")

Layer 4: Application Controls

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class ApplicationSecurityLayer:
    def __init__(self):
        self.applications = {}
        self.security_controls = {}
        self.vulnerability_scans = {}
        self.code_analysis = {}
    
    def register_application(self, app_id, app_config):
        """Register application"""
        self.applications[app_id] = {
            'app_id': app_id,
            'name': app_config['name'],
            'type': app_config['type'],
            'version': app_config.get('version', '1.0'),
            'security_controls': app_config.get('security_controls', []),
            'vulnerability_status': 'unknown',
            'last_scan': None,
            'security_score': 0.0
        }
    
    def implement_security_control(self, control_id, control_config):
        """Implement application security control"""
        self.security_controls[control_id] = {
            'control_id': control_id,
            'type': control_config['type'],
            'application_id': control_config['application_id'],
            'implementation': control_config['implementation'],
            'status': 'active',
            'effectiveness': control_config.get('effectiveness', 0.0),
            'last_test': None
        }
    
    def perform_vulnerability_scan(self, app_id, scan_type='automated'):
        """Perform vulnerability scan"""
        if app_id not in self.applications:
            return None
        
        scan_id = f"SCAN-{app_id}-{datetime.now().strftime('%Y%m%d%H%M%S')}"
        
        # Simulate vulnerability scan
        vulnerabilities = self.simulate_vulnerability_scan(app_id)
        
        self.vulnerability_scans[scan_id] = {
            'scan_id': scan_id,
            'app_id': app_id,
            'scan_type': scan_type,
            'timestamp': datetime.now(),
            'vulnerabilities': vulnerabilities,
            'total_vulnerabilities': len(vulnerabilities),
            'critical_count': len([v for v in vulnerabilities if v['severity'] == 'critical']),
            'high_count': len([v for v in vulnerabilities if v['severity'] == 'high']),
            'medium_count': len([v for v in vulnerabilities if v['severity'] == 'medium']),
            'low_count': len([v for v in vulnerabilities if v['severity'] == 'low'])
        }
        
        # Update application status
        self.applications[app_id]['vulnerability_status'] = self.calculate_vulnerability_status(vulnerabilities)
        self.applications[app_id]['last_scan'] = datetime.now()
        
        return self.vulnerability_scans[scan_id]
    
    def simulate_vulnerability_scan(self, app_id):
        """Simulate vulnerability scan"""
        # Simulation of common vulnerabilities
        vulnerabilities = [
            {
                'id': f'VULN-{app_id}-001',
                'type': 'SQL Injection',
                'severity': 'high',
                'cvss_score': 8.5,
                'description': 'SQL injection vulnerability in login form',
                'location': '/login.php',
                'remediation': 'Use parameterized queries'
            },
            {
                'id': f'VULN-{app_id}-002',
                'type': 'Cross-Site Scripting (XSS)',
                'severity': 'medium',
                'cvss_score': 6.1,
                'description': 'Reflected XSS in search functionality',
                'location': '/search.php',
                'remediation': 'Implement input validation and output encoding'
            },
            {
                'id': f'VULN-{app_id}-003',
                'type': 'Insecure Direct Object Reference',
                'severity': 'medium',
                'cvss_score': 5.3,
                'description': 'Direct access to user files without authorization',
                'location': '/files.php',
                'remediation': 'Implement proper authorization checks'
            }
        ]
        
        return vulnerabilities
    
    def calculate_vulnerability_status(self, vulnerabilities):
        """Calculate vulnerability status"""
        if not vulnerabilities:
            return 'clean'
        
        critical_count = len([v for v in vulnerabilities if v['severity'] == 'critical'])
        high_count = len([v for v in vulnerabilities if v['severity'] == 'high'])
        
        if critical_count > 0:
            return 'critical'
        elif high_count > 2:
            return 'high'
        elif high_count > 0 or len(vulnerabilities) > 5:
            return 'medium'
        else:
            return 'low'
    
    def perform_code_analysis(self, app_id, code_files):
        """Perform code analysis"""
        analysis_id = f"CODE-{app_id}-{datetime.now().strftime('%Y%m%d%H%M%S')}"
        
        # Simulate code analysis
        issues = self.simulate_code_analysis(code_files)
        
        self.code_analysis[analysis_id] = {
            'analysis_id': analysis_id,
            'app_id': app_id,
            'timestamp': datetime.now(),
            'files_analyzed': len(code_files),
            'issues': issues,
            'total_issues': len(issues),
            'security_issues': len([i for i in issues if i['type'] == 'security']),
            'quality_issues': len([i for i in issues if i['type'] == 'quality']),
            'performance_issues': len([i for i in issues if i['type'] == 'performance'])
        }
        
        return self.code_analysis[analysis_id]
    
    def simulate_code_analysis(self, code_files):
        """Simulate code analysis"""
        issues = []
        
        for file in code_files:
            if 'password' in file.lower():
                issues.append({
                    'file': file,
                    'line': 15,
                    'type': 'security',
                    'severity': 'high',
                    'description': 'Hardcoded password detected',
                    'rule': 'SEC001'
                })
            
            if 'sql' in file.lower():
                issues.append({
                    'file': file,
                    'line': 42,
                    'type': 'security',
                    'severity': 'medium',
                    'description': 'Potential SQL injection vulnerability',
                    'rule': 'SEC002'
                })
        
        return issues
    
    def get_application_security_summary(self, app_id):
        """Get application security summary"""
        if app_id not in self.applications:
            return None
        
        app = self.applications[app_id]
        
        # Get recent scans
        recent_scans = [scan for scan in self.vulnerability_scans.values() 
                       if scan['app_id'] == app_id and 
                       scan['timestamp'] >= datetime.now() - timedelta(days=30)]
        
        # Get recent code analyses
        recent_analyses = [analysis for analysis in self.code_analysis.values() 
                          if analysis['app_id'] == app_id and 
                          analysis['timestamp'] >= datetime.now() - timedelta(days=30)]
        
        summary = {
            'app_id': app_id,
            'name': app['name'],
            'vulnerability_status': app['vulnerability_status'],
            'total_vulnerabilities': sum(scan['total_vulnerabilities'] for scan in recent_scans),
            'critical_vulnerabilities': sum(scan['critical_count'] for scan in recent_scans),
            'security_issues': sum(analysis['security_issues'] for analysis in recent_analyses),
            'last_scan': app['last_scan'],
            'security_score': self.calculate_security_score(app, recent_scans, recent_analyses)
        }
        
        return summary
    
    def calculate_security_score(self, app, scans, analyses):
        """Calculate security score"""
        base_score = 100.0
        
        # Penalize for vulnerabilities
        for scan in scans:
            base_score -= scan['critical_count'] * 20
            base_score -= scan['high_count'] * 10
            base_score -= scan['medium_count'] * 5
            base_score -= scan['low_count'] * 1
        
        # Penalize for code problems
        for analysis in analyses:
            base_score -= analysis['security_issues'] * 5
        
        return max(0.0, base_score)

# Usage example
app_layer = ApplicationSecurityLayer()

# Register application
app_layer.register_application('APP-001', {
    'name': 'Customer Portal',
    'type': 'Web Application',
    'version': '2.1',
    'security_controls': ['WAF', 'Input Validation', 'Authentication']
})

# Perform vulnerability scan
scan_result = app_layer.perform_vulnerability_scan('APP-001')
print(f"Scan result: {scan_result['total_vulnerabilities']} vulnerabilities found")

# Perform code analysis
code_analysis = app_layer.perform_code_analysis('APP-001', ['login.php', 'search.php', 'database.php'])
print(f"Code analysis: {code_analysis['total_issues']} issues found")

# Get security summary
security_summary = app_layer.get_application_security_summary('APP-001')
print(f"Security summary: {security_summary}")

Defense in Depth Implementation

Implementation Strategy

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class DefenseInDepthStrategy:
    def __init__(self):
        self.layers = {
            'policies': PolicyLayer(),
            'physical': PhysicalSecurityLayer(),
            'network': NetworkSecurityLayer(),
            'application': ApplicationSecurityLayer()
        }
        self.integration_points = {}
        self.coordination_mechanisms = {}
    
    def assess_overall_security(self):
        """Assess overall security"""
        layer_scores = {}
        
        for layer_name, layer in self.layers.items():
            if hasattr(layer, 'assess_policy_coverage'):
                layer_scores[layer_name] = layer.assess_policy_coverage()
            elif hasattr(layer, 'assess_physical_security'):
                layer_scores[layer_name] = layer.assess_physical_security()['security_score']
            elif hasattr(layer, 'get_network_security_status'):
                layer_scores[layer_name] = layer.get_network_security_status()['security_score']
            else:
                layer_scores[layer_name] = 0.0
        
        # Calculate overall score
        overall_score = sum(layer_scores.values()) / len(layer_scores)
        
        return {
            'layer_scores': layer_scores,
            'overall_score': overall_score,
            'weakest_layer': min(layer_scores, key=layer_scores.get),
            'strongest_layer': max(layer_scores, key=layer_scores.get),
            'recommendations': self.get_improvement_recommendations(layer_scores)
        }
    
    def get_improvement_recommendations(self, layer_scores):
        """Get improvement recommendations"""
        recommendations = []
        
        for layer, score in layer_scores.items():
            if score < 0.7:
                recommendations.append(f"Improve {layer} layer (current score: {score:.2f})")
        
        if len(recommendations) == 0:
            recommendations.append("Maintain and monitor all layers")
        
        return recommendations
    
    def coordinate_incident_response(self, incident_type, affected_layers):
        """Coordinate incident response between layers"""
        response_actions = []
        
        for layer in affected_layers:
            if layer in self.layers:
                if layer == 'policies':
                    response_actions.append("Update relevant policies")
                elif layer == 'physical':
                    response_actions.append("Strengthen physical controls")
                elif layer == 'network':
                    response_actions.append("Apply additional firewall rules")
                elif layer == 'application':
                    response_actions.append("Implement additional application controls")
        
        return {
            'incident_type': incident_type,
            'affected_layers': affected_layers,
            'response_actions': response_actions,
            'coordination_required': len(affected_layers) > 1
        }

# Usage example
defense_strategy = DefenseInDepthStrategy()

# Assess overall security
security_assessment = defense_strategy.assess_overall_security()
print(f"Security assessment: {security_assessment}")

# Coordinate incident response
incident_response = defense_strategy.coordinate_incident_response(
    'data_breach', 
    ['network', 'application']
)
print(f"Incident response: {incident_response}")

Best Practices

Layer Design

  • Intelligent Redundancy: Multiple controls for the same threat
  • Diversity: Different types of controls
  • Depth: Multiple levels of defense
  • Coverage: Complete protection

Implementation

  • Gradual Approach: Implementation by layers
  • Integration: Integration between layers
  • Monitoring: Monitoring of all layers
  • Testing: Regular effectiveness testing

Operation

  • Coordination: Coordination between layers
  • Response: Coordinated response to incidents
  • Improvement: Continuous layer improvement
  • Training: Staff training

References