🤖system prompt•7 months ago
security-requirement-extraction
Derive security requirements from threat models and business
# Security Requirement Extraction
Transform threat analysis into actionable security requirements.
## When to Use This Skill
- Converting threat models to requirements
- Writing security user stories
- Creating security test cases
- Building security acceptance criteria
- Compliance requirement mapping
- Security architecture documentation
## Core Concepts
### 1. Requirement Categories
```
Business Requirements → Security Requirements → Technical Controls
↓ ↓ ↓
"Protect customer "Encrypt PII at rest" "AES-256 encryption
data" with KMS key rotation"
```
### 2. Security Requirement Types
| Type | Focus | Example |
| ------------------ | ----------------------- | ------------------------------------- |
| **Functional** | What system must do | "System must authenticate users" |
| **Non-functional** | How system must perform | "Authentication must complete in <2s" |
| **Constraint** | Limitations imposed | "Must use approved crypto libraries" |
### 3. Requirement Attributes
| Attribute | Description |
| ---------------- | --------------------------- |
| **Traceability** | Links to threats/compliance |
| **Testability** | Can be verified |
| **Priority** | Business importance |
| **Risk Level** | Impact if not met |
## Templates
### Template 1: Security Requirement Model
```python
from dataclasses import dataclass, field
from enum import Enum
from typing import List, Dict, Optional, Set
from datetime import datetime
class RequirementType(Enum):
FUNCTIONAL = "functional"
NON_FUNCTIONAL = "non_functional"
CONSTRAINT = "constraint"
class Priority(Enum):
CRITICAL = 1
HIGH = 2
MEDIUM = 3
LOW = 4
class SecurityDomain(Enum):
AUTHENTICATION = "authentication"
AUTHORIZATION = "authorization"
DATA_PROTECTION = "data_protection"
AUDIT_LOGGING = "audit_logging"
INPUT_VALIDATION = "input_validation"
ERROR_HANDLING = "error_handling"
SESSION_MANAGEMENT = "session_management"
CRYPTOGRAPHY = "cryptography"
NETWORK_SECURITY = "network_security"
AVAILABILITY = "availability"
class ComplianceFramework(Enum):
PCI_DSS = "pci_dss"
HIPAA = "hipaa"
GDPR = "gdpr"
SOC2 = "soc2"
NIST_CSF = "nist_csf"
ISO_27001 = "iso_27001"
OWASP = "owasp"
@dataclass
class SecurityRequirement:
id: str
title: str
description: str
req_type: RequirementType
domain: SecurityDomain
priority: Priority
rationale: str = ""
acceptance_criteria: List[str] = field(default_factory=list)
test_cases: List[str] = field(default_factory=list)
threat_refs: List[str] = field(default_factory=list)
compliance_refs: List[str] = field(default_factory=list)
dependencies: List[str] = field(default_factory=list)
status: str = "draft"
owner: str = ""
created_date: datetime = field(default_factory=datetime.now)
def to_user_story(self) -> str:
"""Convert to user story format."""
return f"""
**{self.id}: {self.title}**
As a security-conscious system,
I need to {self.description.lower()},
So that {self.rationale.lower()}.
**Acceptance Criteria:**
{chr(10).join(f'- [ ] {ac}' for ac in self.acceptance_criteria)}
**Priority:** {self.priority.name}
**Domain:** {self.domain.value}
**Threat References:** {', '.join(self.threat_refs)}
"""
def to_test_spec(self) -> str:
"""Convert to test specification."""
return f"""
## Test Specification: {self.id}
### Requirement
{self.description}
### Test Cases
{chr(10).join(f'{i+1}. {tc}' for i, tc in enumerate(self.test_cases))}
### Acceptance Criteria Verification
{chr(10).join(f'- {ac}' for ac in self.acceptance_criteria)}
"""
@dataclass
class RequirementSet:
name: str
version: str
requirements: List[SecurityRequirement] = field(default_factory=list)
def add(self, req: SecurityRequirement) -> None:
self.requirements.append(req)
def get_by_domain(self, domain: SecurityDomain) -> List[SecurityRequirement]:
return [r for r in self.requirements if r.domain == domain]
def get_by_priority(self, priority: Priority) -> List[SecurityRequirement]:
return [r for r in self.requirements if r.priority == priority]
def get_by_threat(self, threat_id: str) -> List[SecurityRequirement]:
return [r for r in self.requirements if threat_id in r.threat_refs]
def get_critical_requirements(self) -> List[SecurityRequirement]:
return [r for r in self.requirements if r.priority == Priority.CRITICAL]
def export_markdown(self) -> str:
"""Export all requirements as markdown."""
lines = [f"# Security Requirements: {self.name}\n"]
lines.append(f"Version: {self.version}\n")
for domain in SecurityDomain:
domain_reqs = self.get_by_domain(domain)
if domain_reqs:
lines.append(f"\n## {domain.value.replace('_', ' ').title()}\n")
for req in domain_reqs:
lines.append(req.to_user_story())
return "\n".join(lines)
def traceability_matrix(self) -> Dict[str, List[str]]:
"""Generate threat-to-requirement traceability."""
matrix = {}
for req in self.requirements:
for threat_id in req.threat_refs:
if threat_id not in matrix:
matrix[threat_id] = []
matrix[threat_id].append(req.id)
return matrix
```
### Template 2: Threat-to-Requirement Extractor
```python
from dataclasses import dataclass
from typing import List, Dict, Tuple
@dataclass
class ThreatInput:
id: str
category: str # STRIDE category
title: str
description: str
target: str
impact: str
likelihood: str
class RequirementExtractor:
"""Extract security requirements from threats."""
# Mapping of STRIDE categories to security domains and requirement patterns
STRIDE_MAPPINGS = {
"SPOOFING": {
"domains": [SecurityDomain.AUTHENTICATION, SecurityDomain.SESSION_MANAGEMENT],
"patterns": [
("Implement strong authentication for {target}",
"Ensure {target} authenticates all users before granting access"),
("Validate identity tokens for {target}",
"All authentication tokens must be cryptographically verified"),
("Implement session management for {target}",
"Sessions must be securely managed with proper expiration"),
]
},
"TAMPERING": {
"domains": [SecurityDomain.INPUT_VALIDATION, SecurityDomain.DATA_PROTECTION],
"patterns": [
("Validate all input to {target}",
"All input must be validated against expected formats"),
("Implement integrity checks for {target}",
"Data integrity must be verified using cryptographic signatures"),
("Protect {target} from modification",
"Implement controls to prevent unauthorized data modification"),
]
},
"REPUDIATION": {
"domains": [SecurityDomain.AUDIT_LOGGING],
"patterns": [
("Log all security events for {target}",
"Security-relevant events must be logged for audit purposes"),
("Implement non-repudiation for {target}",
"Critical actions must have cryptographic proof of origin"),
("Protect audit logs for {target}",
"Audit logs must be tamper-evident and protected"),
]
},
"INFORMATION_DISCLOSURE": {
"domains": [SecurityDomain.DATA_PROTECTION, SecurityDomain.CRYPTOGRAPHY],
"patterns": [
("Encrypt sensitive data in {target}",
"Sensitive data must be encrypted at rest and in transit"),
("Implement access controls for {target}",
"Data access must be restricted based on need-to-know"),
("Prevent information leakage from {target}",
"Error messages and logs must not expose sensitive information"),
]
},
"DENIAL_OF_SERVICE": {
"domains": [SecurityDomain.AVAILABILITY, SecurityDomain.INPUT_VALIDATION],
"patterns": [
("Implement rate limiting for {target}",
"Requests must be rate-limited to prevent resource exhaustion"),
("Ensure availability of {target}",
"System must remain available under high load conditions"),
("Implement resource quotas for {target}",
"Resource consumption must be bounded and monitored"),
]
},
"ELEVATION_OF_PRIVILEGE": {
"domains": [SecurityDomain.AUTHORIZATION],
"patterns": [
("Enforce authorization for {target}",
"All actions must be authorized based on user permissions"),
("Implement least privilege for {target}",
"Users must only have minimum necessary permissions"),
("Validate permissions for {target}",
"Permission checks must be performed server-side"),
]
},
}
def extract_requirements(
self,
threats: List[ThreatInput],
project_name: str
) -> RequirementSet:
"""Extract security requirements from threats."""
req_set = RequirementSet(
name=f"{project_name} Security Requirements",
version="1.0"
)
req_counter = 1
for threat in threats:
reqs = self._threat_to_requirements(threat, req_counter)
for req in reqs:
req_set.add(req)
req_counter += len(reqs)
return req_set
def _threat_to_requirements(
self,
threat: ThreatInput,
start_id: int
) -> List[SecurityRequirement]:
"""Convert a single threat to requirements."""
requirements = []
mapping = self.STRIDE_MAPPINGS.get(threat.category, {})
domains = mapping.get("domains", [])
patterns = mapping.get("patterns", [])
priority = self._calculate_priority(threat.impact, threat.likelihood)
for i, (title_pattern, desc_pattern) in enumerate(patterns):
req = SecurityRequirement(
id=f"SR-{start_id + i:03d}",
title=title_pattern.format(target=threat.target),
description=desc_pattern.format(target=threat.target),
req_type=RequirementType.FUNCTIONAL,
domain=domains[i % len(domains)] if domains else SecurityDomain.DATA_PROTECTION,
priority=priority,
rationale=f"Mitigates threat: {threat.title}",
threat_refs=[threat.id],
acceptance_criteria=self._generate_acceptance_criteria(
threat.category, threat.target
),
test_cases=self._generate_test_cases(
threat.category, threat.target
)
)
requirements.append(req)
return requirements
def _calculate_priority(self, impact: str, likelihood: str) -> Priority:
"""Calculate requirement priority from threat attributes."""
score_map = {"LOW": 1, "MEDIUM": 2, "HIGH": 3, "CRITICAL": 4}
impact_score = score_map.get(impact.upper(), 2)
likelihood_score = score_map.get(likelihood.upper(), 2)
combined = impact_score * likelihood_score
if combined >= 12:
return Priority.CRITICAL
elif combined >= 6:
return Priority.HIGH
elif combined >= 3:
return Priority.MEDIUM
return Priority.LOW
def _generate_acceptance_criteria(
self,
category: str,
target: str
) -> List[str]:
"""Generate acceptance criteria for requirement."""
criteria_templates = {
"SPOOFING": [
f"Users must authenticate before accessing {target}",
"Authentication failures are logged and monitored",
"Multi-factor authentication is available for sensitive operations",
],
"TAMPERING": [
f"All input to {target} is validated",
"Data integrity is verified before processing",
"Modification attempts trigger alerts",
],
"REPUDIATION": [
f"All actions on {target} are logged with user identity",
"Logs cannot be modified by regular users",
"Log retention meets compliance requirements",
],
"INFORMATION_DISCLOSURE": [
f"Sensitive data in {target} is encrypted",
"Access to sensitive data is logged",
"Error messages do not reveal sensitive information",
],
"DENIAL_OF_SERVICE": [
f"Rate limiting is enforced on {target}",
"System degrades gracefully under load",
"Resource exhaustion triggers alerts",
],
"ELEVATION_OF_PRIVILEGE": [
f"Authorization is checked for all {target} operations",
"Users cannot access resources beyond their permissions",
"Privilege changes are logged and monitored",
],
}
return criteria_templates.get(category, [])
def _generate_test_cases(
self,
category: str,
target: str
) -> List[str]:
"""Generate test cases for requirement."""
test_templates = {
"SPOOFING": [
f"Test: Unauthenticated access to {target} is denied",
"Test: Invalid credentials are rejected",
"Test: Session tokens cannot be forged",
],
"TAMPERING": [
f"Test: Invalid input to {target} is rejected",
"Test: Tampered data is detected and rejected",
"Test: SQL injection attempts are blocked",
],
"REPUDIATION": [
"Test: Security events are logged",
"Test: Logs include sufficient detail for forensics",
"Test: Log integrity is protected",
],
"INFORMATION_DISCLOSURE": [
f"Test: {target} data is encrypted in transit",
f"Test: {target} data is encrypted at rest",
"Test: Error messages are sanitized",
],
"DENIAL_OF_SERVICE": [
f"Test: Rate limiting on {target} works correctly",
"Test: System handles burst traffic gracefully",
"Test: Resource limits are enforced",
],
"ELEVATION_OF_PRIVILEGE": [
f"Test: Unauthorized access to {target} is denied",
"Test: Privilege escalation attempts are blocked",
"Test: IDOR vulnerabilities are not present",
],
}
return test_templates.get(category, [])
```
### Template 3: Compliance Mapping
```python
from typing import Dict, List, Set
class ComplianceMapper:
"""Map security requirements to compliance frameworks."""
FRAMEWORK_CONTROLS = {
ComplianceFramework.PCI_DSS: {
SecurityDomain.AUTHENTICATION: ["8.1", "8.2", "8.3"],
SecurityDomain.AUTHORIZATION: ["7.1", "7.2"],
SecurityDomain.DATA_PROTECTION: ["3.4", "3.5", "4.1"],
SecurityDomain.AUDIT_LOGGING: ["10.1", "10.2", "10.3"],
SecurityDomain.NETWORK_SECURITY: ["1.1", "1.2", "1.3"],
SecurityDomain.CRYPTOGRAPHY: ["3.5", "3.6", "4.1"],
},
ComplianceFramework.HIPAA: {
SecurityDomain.AUTHENTICATION: ["164.312(d)"],
SecurityDomain.AUTHORIZATION: ["164.312(a)(1)"],
SecurityDomain.DATA_PROTECTION: ["164.312(a)(2)(iv)", "164.312(e)(2)(ii)"],
SecurityDomain.AUDIT_LOGGING: ["164.312(b)"],
},
ComplianceFramework.GDPR: {
SecurityDomain.DATA_PROTECTION: ["Art. 32", "Art. 25"],
SecurityDomain.AUDIT_LOGGING: ["Art. 30"],
SecurityDomain.AUTHORIZATION: ["Art. 25"],
},
ComplianceFramework.OWASP: {
SecurityDomain.AUTHENTICATION: ["V2.1", "V2.2", "V2.3"],
SecurityDomain.SESSION_MANAGEMENT: ["V3.1", "V3.2", "V3.3"],
SecurityDomain.INPUT_VALIDATION: ["V5.1", "V5.2", "V5.3"],
SecurityDomain.CRYPTOGRAPHY: ["V6.1", "V6.2"],
SecurityDomain.ERROR_HANDLING: ["V7.1", "V7.2"],
SecurityDomain.DATA_PROTECTION: ["V8.1", "V8.2", "V8.3"],
SecurityDomain.AUDIT_LOGGING: ["V7.1", "V7.2"],
},
}
def map_requirement_to_compliance(
self,
requirement: SecurityRequirement,
frameworks: List[ComplianceFramework]
) -> Dict[str, List[str]]:
"""Map a requirement to compliance controls."""
mapping = {}
for framework in frameworks:
controls = self.FRAMEWORK_CONTROLS.get(framework, {})
domain_controls = controls.get(requirement.domain, [])
if domain_controls:
mapping[framework.value] = domain_controls
return mapping
def get_requirements_for_control(
self,
requirement_set: RequirementSet,
framework: ComplianceFramework,
control_id: str
) -> List[SecurityRequirement]:
"""Find requirements that satisfy a compliance control."""
matching = []
framework_controls = self.FRAMEWORK_CONTROLS.get(framework, {})
for domain, controls in framework_controls.items():
if control_id in controls:
matching.extend(requirement_set.get_by_domain(domain))
return matching
def generate_compliance_matrix(
self,
requirement_set: RequirementSet,
frameworks: List[ComplianceFramework]
) -> Dict[str, Dict[str, List[str]]]:
"""Generate compliance traceability matrix."""
matrix = {}
for framework in frameworks:
matrix[framework.value] = {}
framework_controls = self.FRAMEWORK_CONTROLS.get(framework, {})
for domain, controls in framework_controls.items():
for control in controls:
reqs = self.get_requirements_for_control(
requirement_set, framework, control
)
if reqs:
matrix[framework.value][control] = [r.id for r in reqs]
return matrix
def gap_analysis(
self,
requirement_set: RequirementSet,
framework: ComplianceFramework
) -> Dict[str, List[str]]:
"""Identify compliance gaps."""
gaps = {"missing_controls": [], "weak_coverage": []}
framework_controls = self.FRAMEWORK_CONTROLS.get(framework, {})
for domain, controls in framework_controls.items():
domain_reqs = requirement_set.get_by_domain(domain)
for