# Information Security Policy Framework

## Overview

This document establishes the comprehensive information security policy framework that protects organizational assets, ensures regulatory compliance, and maintains business continuity through robust security controls and risk management practices.

## Security Governance Structure

### Security Organization

**Chief Information Security Officer (CISO)**
- Overall security strategy and governance
- Risk management and compliance oversight
- Security budget and resource allocation
- Board and executive reporting

**Security Operations Center (SOC)**
- 24/7 security monitoring and incident response
- Threat detection and analysis
- Security event correlation and investigation
- Incident escalation and coordination

**Security Architecture Team**
- Security design and implementation standards
- Technology evaluation and selection
- Security control design and validation
- Architecture review and approval

### Security Policies Hierarchy

```yaml
security_policy_framework:
  level_1_policies:
    - information_security_policy
    - acceptable_use_policy
    - incident_response_policy
    - business_continuity_policy
  
  level_2_standards:
    - access_control_standards
    - encryption_standards
    - network_security_standards
    - application_security_standards
  
  level_3_procedures:
    - user_provisioning_procedures
    - vulnerability_management_procedures
    - security_monitoring_procedures
    - compliance_audit_procedures
  
  level_4_guidelines:
    - secure_coding_guidelines
    - security_awareness_guidelines
    - vendor_security_guidelines
    - remote_work_guidelines
```

## Access Control Framework

### Identity and Access Management (IAM)

**Access Control Principles:**
- Principle of Least Privilege
- Need-to-Know Basis
- Separation of Duties
- Regular Access Reviews

**Role-Based Access Control (RBAC):**
```yaml
rbac_framework:
  roles:
    security_admin:
      permissions:
        - security_policy_management
        - incident_response_coordination
        - security_tool_administration
      restrictions:
        - no_production_data_access
        - audit_trail_required
    
    system_admin:
      permissions:
        - infrastructure_management
        - system_configuration
        - backup_operations
      restrictions:
        - no_security_policy_changes
        - change_approval_required
    
    developer:
      permissions:
        - code_repository_access
        - development_environment_access
        - testing_tool_access
      restrictions:
        - no_production_access
        - code_review_required
    
    business_user:
      permissions:
        - application_access
        - business_data_access
        - reporting_tools_access
      restrictions:
        - data_classification_based_access
        - time_based_access_controls
```

**Multi-Factor Authentication (MFA):**
```python
# MFA implementation framework
from enum import Enum
from dataclasses import dataclass
from typing import List, Optional

class AuthenticationFactor(Enum):
    SOMETHING_YOU_KNOW = "password"  # Knowledge factor
    SOMETHING_YOU_HAVE = "token"     # Possession factor
    SOMETHING_YOU_ARE = "biometric"  # Inherence factor

@dataclass
class MFAPolicy:
    resource_classification: str
    required_factors: List[AuthenticationFactor]
    session_timeout: int  # minutes
    re_authentication_required: bool

class MFAManager:
    def __init__(self):
        self.policies = {
            'restricted': MFAPolicy(
                resource_classification='restricted',
                required_factors=[
                    AuthenticationFactor.SOMETHING_YOU_KNOW,
                    AuthenticationFactor.SOMETHING_YOU_HAVE,
                    AuthenticationFactor.SOMETHING_YOU_ARE
                ],
                session_timeout=15,
                re_authentication_required=True
            ),
            'confidential': MFAPolicy(
                resource_classification='confidential',
                required_factors=[
                    AuthenticationFactor.SOMETHING_YOU_KNOW,
                    AuthenticationFactor.SOMETHING_YOU_HAVE
                ],
                session_timeout=60,
                re_authentication_required=False
            ),
            'internal': MFAPolicy(
                resource_classification='internal',
                required_factors=[
                    AuthenticationFactor.SOMETHING_YOU_KNOW
                ],
                session_timeout=480,
                re_authentication_required=False
            )
        }
    
    def get_authentication_requirements(self, resource_classification: str) -> MFAPolicy:
        """Get MFA requirements based on resource classification"""
        return self.policies.get(resource_classification, self.policies['internal'])
    
    def validate_authentication(self, user_id: str, factors_provided: List[str], 
                              resource_classification: str) -> bool:
        """Validate if provided authentication factors meet policy requirements"""
        
        policy = self.get_authentication_requirements(resource_classification)
        required_factor_types = [factor.value for factor in policy.required_factors]
        
        # Check if all required factor types are provided
        for required_type in required_factor_types:
            if not any(factor.startswith(required_type) for factor in factors_provided):
                return False
        
        return True
```

## Network Security Standards

### Network Segmentation

**Network Security Zones:**
```yaml
network_zones:
  dmz:
    description: "Demilitarized zone for public-facing services"
    security_level: "high"
    allowed_protocols: ["HTTPS", "SSH"]
    monitoring: "enhanced"
    
  internal:
    description: "Internal corporate network"
    security_level: "medium"
    allowed_protocols: ["HTTP", "HTTPS", "SSH", "RDP"]
    monitoring: "standard"
    
  restricted:
    description: "High-security zone for sensitive systems"
    security_level: "maximum"
    allowed_protocols: ["HTTPS"]
    monitoring: "comprehensive"
    
  guest:
    description: "Guest network for visitors"
    security_level: "low"
    allowed_protocols: ["HTTP", "HTTPS"]
    monitoring: "basic"
```

**Firewall Rules Framework:**
```python
# Network security rule engine
from dataclasses import dataclass
from typing import List, Optional
from enum import Enum

class Action(Enum):
    ALLOW = "allow"
    DENY = "deny"
    LOG = "log"

class Protocol(Enum):
    TCP = "tcp"
    UDP = "udp"
    ICMP = "icmp"

@dataclass
class FirewallRule:
    rule_id: str
    source_zone: str
    destination_zone: str
    protocol: Protocol
    source_port: Optional[str]
    destination_port: str
    action: Action
    logging_enabled: bool
    description: str

class NetworkSecurityManager:
    def __init__(self):
        self.default_rules = self.load_default_rules()
        self.custom_rules = []
    
    def load_default_rules(self) -> List[FirewallRule]:
        """Load default security rules"""
        return [
            FirewallRule(
                rule_id="DEFAULT_001",
                source_zone="dmz",
                destination_zone="internal",
                protocol=Protocol.TCP,
                source_port=None,
                destination_port="443",
                action=Action.ALLOW,
                logging_enabled=True,
                description="Allow HTTPS from DMZ to internal"
            ),
            FirewallRule(
                rule_id="DEFAULT_002",
                source_zone="guest",
                destination_zone="internal",
                protocol=Protocol.TCP,
                source_port=None,
                destination_port="*",
                action=Action.DENY,
                logging_enabled=True,
                description="Deny all traffic from guest to internal"
            ),
            FirewallRule(
                rule_id="DEFAULT_003",
                source_zone="*",
                destination_zone="restricted",
                protocol=Protocol.TCP,
                source_port=None,
                destination_port="*",
                action=Action.DENY,
                logging_enabled=True,
                description="Default deny to restricted zone"
            )
        ]
    
    def evaluate_traffic(self, source_zone: str, destination_zone: str, 
                        protocol: str, destination_port: str) -> Action:
        """Evaluate network traffic against security rules"""
        
        all_rules = self.default_rules + self.custom_rules
        
        # Sort rules by priority (specific rules first)
        sorted_rules = sorted(all_rules, key=lambda r: self.calculate_rule_priority(r))
        
        for rule in sorted_rules:
            if self.rule_matches(rule, source_zone, destination_zone, protocol, destination_port):
                if rule.logging_enabled:
                    self.log_traffic_decision(rule, source_zone, destination_zone, protocol, destination_port)
                return rule.action
        
        # Default deny
        return Action.DENY
```

## Application Security Framework

### Secure Development Lifecycle (SDLC)

**Security Gates in SDLC:**
```yaml
sdlc_security_gates:
  requirements_phase:
    activities:
      - security_requirements_analysis
      - threat_modeling_initiation
      - compliance_requirements_review
    deliverables:
      - security_requirements_document
      - initial_threat_model
    
  design_phase:
    activities:
      - security_architecture_review
      - threat_modeling_completion
      - security_control_design
    deliverables:
      - security_architecture_document
      - detailed_threat_model
      - security_control_specifications
    
  implementation_phase:
    activities:
      - secure_coding_practices
      - static_code_analysis
      - dependency_vulnerability_scanning
    deliverables:
      - secure_code_review_report
      - sast_scan_results
      - dependency_scan_results
    
  testing_phase:
    activities:
      - dynamic_security_testing
      - penetration_testing
      - security_test_case_execution
    deliverables:
      - dast_scan_results
      - penetration_test_report
      - security_test_results
    
  deployment_phase:
    activities:
      - security_configuration_review
      - runtime_security_validation
      - security_monitoring_setup
    deliverables:
      - security_configuration_checklist
      - deployment_security_report
```

**Secure Coding Standards:**
```python
# Secure coding validation framework
import re
from typing import List, Dict
from dataclasses import dataclass

@dataclass
class SecurityViolation:
    rule_id: str
    severity: str
    description: str
    line_number: int
    code_snippet: str
    remediation: str

class SecureCodeAnalyzer:
    def __init__(self):
        self.security_rules = self.load_security_rules()
    
    def load_security_rules(self) -> Dict:
        """Load secure coding rules"""
        return {
            'sql_injection': {
                'pattern': r'(SELECT|INSERT|UPDATE|DELETE).*\+.*\$',
                'severity': 'high',
                'description': 'Potential SQL injection vulnerability',
                'remediation': 'Use parameterized queries or prepared statements'
            },
            'hardcoded_secrets': {
                'pattern': r'(password|secret|key|token)\s*=\s*["\'][^"\']+["\']',
                'severity': 'critical',
                'description': 'Hardcoded secrets detected',
                'remediation': 'Use environment variables or secure secret management'
            },
            'xss_vulnerability': {
                'pattern': r'innerHTML\s*=.*\+',
                'severity': 'medium',
                'description': 'Potential XSS vulnerability',
                'remediation': 'Use safe DOM manipulation methods and input sanitization'
            },
            'weak_crypto': {
                'pattern': r'(MD5|SHA1)\(',
                'severity': 'medium',
                'description': 'Weak cryptographic algorithm',
                'remediation': 'Use SHA-256 or stronger cryptographic algorithms'
            }
        }
    
    def analyze_code(self, code_content: str, file_path: str) -> List[SecurityViolation]:
        """Analyze code for security violations"""
        
        violations = []
        lines = code_content.split('\n')
        
        for line_num, line in enumerate(lines, 1):
            for rule_id, rule in self.security_rules.items():
                if re.search(rule['pattern'], line, re.IGNORECASE):
                    violation = SecurityViolation(
                        rule_id=rule_id,
                        severity=rule['severity'],
                        description=rule['description'],
                        line_number=line_num,
                        code_snippet=line.strip(),
                        remediation=rule['remediation']
                    )
                    violations.append(violation)
        
        return violations
    
    def generate_security_report(self, violations: List[SecurityViolation]) -> Dict:
        """Generate security analysis report"""
        
        severity_counts = {'critical': 0, 'high': 0, 'medium': 0, 'low': 0}
        
        for violation in violations:
            severity_counts[violation.severity] += 1
        
        return {
            'total_violations': len(violations),
            'severity_breakdown': severity_counts,
            'violations': [
                {
                    'rule_id': v.rule_id,
                    'severity': v.severity,
                    'description': v.description,
                    'line_number': v.line_number,
                    'code_snippet': v.code_snippet,
                    'remediation': v.remediation
                }
                for v in violations
            ],
            'security_score': self.calculate_security_score(severity_counts)
        }
    
    def calculate_security_score(self, severity_counts: Dict[str, int]) -> float:
        """Calculate security score based on violations"""
        
        weights = {'critical': 10, 'high': 5, 'medium': 2, 'low': 1}
        total_weight = sum(count * weights[severity] for severity, count in severity_counts.items())
        
        # Score from 0-100, where 100 is perfect (no violations)
        max_possible_score = 100
        penalty = min(total_weight * 2, max_possible_score)
        
        return max(0, max_possible_score - penalty)
```

## Incident Response Framework

### Incident Classification

**Incident Severity Levels:**
```yaml
incident_classification:
  severity_1_critical:
    description: "Complete system outage or data breach"
    response_time: "15 minutes"
    escalation: "immediate_ciso_notification"
    communication: "executive_team_and_board"
    
  severity_2_high:
    description: "Significant service degradation or security compromise"
    response_time: "1 hour"
    escalation: "security_manager_notification"
    communication: "management_team"
    
  severity_3_medium:
    description: "Limited service impact or potential security issue"
    response_time: "4 hours"
    escalation: "team_lead_notification"
    communication: "affected_teams"
    
  severity_4_low:
    description: "Minor issues or informational security events"
    response_time: "24 hours"
    escalation: "standard_workflow"
    communication: "internal_team"
```

**Incident Response Procedures:**
```python
# Incident response management system
from datetime import datetime, timedelta
from enum import Enum
from dataclasses import dataclass
from typing import List, Optional

class IncidentSeverity(Enum):
    CRITICAL = 1
    HIGH = 2
    MEDIUM = 3
    LOW = 4

class IncidentStatus(Enum):
    REPORTED = "reported"
    INVESTIGATING = "investigating"
    CONTAINED = "contained"
    RESOLVED = "resolved"
    CLOSED = "closed"

@dataclass
class IncidentResponse:
    incident_id: str
    severity: IncidentSeverity
    description: str
    reporter: str
    assigned_team: str
    status: IncidentStatus
    created_at: datetime
    response_deadline: datetime
    resolution_deadline: datetime

class IncidentManager:
    def __init__(self):
        self.response_times = {
            IncidentSeverity.CRITICAL: timedelta(minutes=15),
            IncidentSeverity.HIGH: timedelta(hours=1),
            IncidentSeverity.MEDIUM: timedelta(hours=4),
            IncidentSeverity.LOW: timedelta(hours=24)
        }
        
        self.resolution_times = {
            IncidentSeverity.CRITICAL: timedelta(hours=4),
            IncidentSeverity.HIGH: timedelta(hours=24),
            IncidentSeverity.MEDIUM: timedelta(days=3),
            IncidentSeverity.LOW: timedelta(days=7)
        }
    
    def create_incident(self, incident_data: Dict) -> IncidentResponse:
        """Create new security incident"""
        
        incident_id = self.generate_incident_id()
        severity = IncidentSeverity(incident_data['severity'])
        created_at = datetime.now()
        
        incident = IncidentResponse(
            incident_id=incident_id,
            severity=severity,
            description=incident_data['description'],
            reporter=incident_data['reporter'],
            assigned_team=self.assign_response_team(severity),
            status=IncidentStatus.REPORTED,
            created_at=created_at,
            response_deadline=created_at + self.response_times[severity],
            resolution_deadline=created_at + self.resolution_times[severity]
        )
        
        # Immediate actions based on severity
        self.initiate_response_actions(incident)
        
        return incident
    
    def initiate_response_actions(self, incident: IncidentResponse):
        """Initiate immediate response actions"""
        
        if incident.severity == IncidentSeverity.CRITICAL:
            # Critical incident actions
            self.activate_incident_command_center()
            self.notify_executive_team(incident)
            self.initiate_containment_procedures(incident)
            
        elif incident.severity == IncidentSeverity.HIGH:
            # High severity actions
            self.notify_security_manager(incident)
            self.assemble_response_team(incident)
            
        # Common actions for all incidents
        self.log_incident(incident)
        self.start_investigation(incident)
        self.notify_assigned_team(incident)
    
    def update_incident_status(self, incident_id: str, new_status: IncidentStatus, 
                             update_notes: str) -> bool:
        """Update incident status with notes"""
        
        incident = self.get_incident(incident_id)
        
        if not incident:
            return False
        
        # Validate status transition
        if not self.is_valid_status_transition(incident.status, new_status):
            raise ValueError(f"Invalid status transition from {incident.status} to {new_status}")
        
        # Update incident
        incident.status = new_status
        
        # Log status change
        self.log_status_change(incident_id, new_status, update_notes)
        
        # Trigger status-specific actions
        if new_status == IncidentStatus.CONTAINED:
            self.initiate_recovery_procedures(incident)
        elif new_status == IncidentStatus.RESOLVED:
            self.begin_post_incident_review(incident)
        
        return True
```

## Compliance and Risk Management

### Compliance Framework

**Regulatory Compliance Requirements:**
```yaml
compliance_frameworks:
  sox_compliance:
    scope: "Financial reporting controls"
    requirements:
      - access_controls_documentation
      - change_management_procedures
      - audit_trail_maintenance
      - segregation_of_duties
    audit_frequency: "annual"
    
  pci_dss:
    scope: "Payment card data protection"
    requirements:
      - network_segmentation
      - encryption_of_cardholder_data
      - vulnerability_management
      - access_control_measures
    audit_frequency: "annual"
    
  iso_27001:
    scope: "Information security management"
    requirements:
      - isms_implementation
      - risk_assessment_procedures
      - security_control_implementation
      - continuous_improvement
    audit_frequency: "annual"
    
  gdpr:
    scope: "Personal data protection"
    requirements:
      - privacy_by_design
      - data_subject_rights
      - breach_notification_procedures
      - data_protection_impact_assessments
    audit_frequency: "continuous"
```

### Risk Assessment Framework

```python
# Security risk assessment system
from enum import Enum
from dataclasses import dataclass
from typing import List, Dict

class RiskLevel(Enum):
    CRITICAL = 5
    HIGH = 4
    MEDIUM = 3
    LOW = 2
    MINIMAL = 1

class Likelihood(Enum):
    VERY_HIGH = 5
    HIGH = 4
    MEDIUM = 3
    LOW = 2
    VERY_LOW = 1

class Impact(Enum):
    CATASTROPHIC = 5
    MAJOR = 4
    MODERATE = 3
    MINOR = 2
    NEGLIGIBLE = 1

@dataclass
class SecurityRisk:
    risk_id: str
    title: str
    description: str
    category: str
    likelihood: Likelihood
    impact: Impact
    risk_level: RiskLevel
    mitigation_controls: List[str]
    residual_risk: RiskLevel
    owner: str
    review_date: datetime

class RiskAssessmentManager:
    def __init__(self):
        self.risk_matrix = self.create_risk_matrix()
    
    def create_risk_matrix(self) -> Dict:
        """Create risk assessment matrix"""
        return {
            (Likelihood.VERY_HIGH, Impact.CATASTROPHIC): RiskLevel.CRITICAL,
            (Likelihood.VERY_HIGH, Impact.MAJOR): RiskLevel.CRITICAL,
            (Likelihood.HIGH, Impact.CATASTROPHIC): RiskLevel.CRITICAL,
            (Likelihood.HIGH, Impact.MAJOR): RiskLevel.HIGH,
            (Likelihood.HIGH, Impact.MODERATE): RiskLevel.HIGH,
            (Likelihood.MEDIUM, Impact.MAJOR): RiskLevel.HIGH,
            (Likelihood.MEDIUM, Impact.MODERATE): RiskLevel.MEDIUM,
            (Likelihood.MEDIUM, Impact.MINOR): RiskLevel.MEDIUM,
            (Likelihood.LOW, Impact.MODERATE): RiskLevel.MEDIUM,
            (Likelihood.LOW, Impact.MINOR): RiskLevel.LOW,
            (Likelihood.VERY_LOW, Impact.MINOR): RiskLevel.LOW,
            # Add all combinations...
        }
    
    def assess_risk(self, risk_data: Dict) -> SecurityRisk:
        """Assess security risk based on likelihood and impact"""
        
        likelihood = Likelihood(risk_data['likelihood'])
        impact = Impact(risk_data['impact'])
        
        # Calculate inherent risk level
        inherent_risk = self.risk_matrix.get((likelihood, impact), RiskLevel.MEDIUM)
        
        # Calculate residual risk after controls
        residual_risk = self.calculate_residual_risk(
            inherent_risk, 
            risk_data.get('mitigation_controls', [])
        )
        
        return SecurityRisk(
            risk_id=self.generate_risk_id(),
            title=risk_data['title'],
            description=risk_data['description'],
            category=risk_data['category'],
            likelihood=likelihood,
            impact=impact,
            risk_level=inherent_risk,
            mitigation_controls=risk_data.get('mitigation_controls', []),
            residual_risk=residual_risk,
            owner=risk_data['owner'],
            review_date=datetime.now() + timedelta(days=90)
        )
    
    def generate_risk_register(self, risks: List[SecurityRisk]) -> Dict:
        """Generate comprehensive risk register"""
        
        risk_summary = {
            'total_risks': len(risks),
            'risk_distribution': {
                'critical': len([r for r in risks if r.residual_risk == RiskLevel.CRITICAL]),
                'high': len([r for r in risks if r.residual_risk == RiskLevel.HIGH]),
                'medium': len([r for r in risks if r.residual_risk == RiskLevel.MEDIUM]),
                'low': len([r for r in risks if r.residual_risk == RiskLevel.LOW]),
                'minimal': len([r for r in risks if r.residual_risk == RiskLevel.MINIMAL])
            },
            'risks_by_category': self.categorize_risks(risks),
            'overdue_reviews': self.find_overdue_reviews(risks),
            'top_risks': self.get_top_risks(risks, 10)
        }
        
        return risk_summary
```
