risk-assessment-methodology（风险评估方法）

Risk Assessment Methodology Skill

Purpose

This skill provides quantitative risk assessment methodology aligned with Hack23 AB's enterprise risk management framework. It enables security professionals and business leaders to systematically identify, analyze, evaluate, and treat risks using defensible statistical methods that demonstrate cybersecurity consulting expertise through measurable, data-driven risk quantification.

When to Use This Skill

Apply this skill when:

• ✅ Conducting quarterly risk assessments
• ✅ Evaluating risks for new products or services
• ✅ Calculating Annual Loss Expectancy (ALE) for control investments
• ✅ Prioritizing risk treatment based on quantitative impact
• ✅ Documenting risk acceptance decisions
• ✅ Creating risk registers for compliance frameworks
• ✅ Performing threat modeling with financial impact
• ✅ Supporting business case for security controls
• ✅ Responding to client risk assessment inquiries

Do NOT use for:

• ❌ Real-time incident response (use incident-response skill)
• ❌ Vulnerability scoring (use vulnerability-management skill)
• ❌ Code security reviews (use secure-code-review skill)

Risk Assessment Process Flow

flowchart TD
    START[🎯 Risk Assessment<br/>Initiation] --> IDENTIFY[📋 Risk Identification<br/>Assets • Threats • Vulnerabilities]

    IDENTIFY --> ANALYZE[🔍 Risk Analysis]

    ANALYZE --> LIKELIHOOD[📊 Likelihood Assessment<br/>Historical + Industry + Expert]
    ANALYZE --> IMPACT[💰 Impact Assessment<br/>Financial • Operational • Reputational]

    LIKELIHOOD --> CALC[🔢 Risk Score Calculation<br/>Probability × Impact × 100]
    IMPACT --> CALC

    CALC --> CATEGORY{Risk Level?}

    CATEGORY -->|400-600| CRITICAL[🔴 Critical Risk<br/>Immediate action required]
    CATEGORY -->|200-399| HIGH[🟠 High Risk<br/>Priority mitigation needed]
    CATEGORY -->|100-199| MEDIUM[🟡 Medium Risk<br/>Planned controls required]
    CATEGORY -->|50-99| LOW[🟢 Low Risk<br/>Monitor and accept]
    CATEGORY -->|1-49| MINIMAL[⚪ Minimal Risk<br/>Accept risk]

    CRITICAL --> TREAT{Treatment<br/>Decision}
    HIGH --> TREAT
    MEDIUM --> TREAT
    LOW --> ACCEPT[✅ Accept Risk<br/>Document in Risk Register]
    MINIMAL --> ACCEPT

    TREAT -->|Reduce| MITIGATE[🛡️ Implement Controls<br/>Reduce likelihood or impact]
    TREAT -->|Transfer| TRANSFER[🤝 Insurance/Outsource<br/>Share financial burden]
    TREAT -->|Avoid| AVOID[🚫 Eliminate Activity<br/>Remove risk source]
    TREAT -->|Accept| ACCEPT_HIGH[📋 Document Acceptance<br/>CEO approval required]

    MITIGATE --> RESIDUAL[📉 Residual Risk<br/>Reassessment]
    TRANSFER --> RESIDUAL
    AVOID --> RESIDUAL
    ACCEPT_HIGH --> RESIDUAL
    ACCEPT --> REGISTER[📊 Risk Register<br/>Tracking & Monitoring]

    RESIDUAL --> REGISTER

    REGISTER --> REVIEW[🔄 Periodic Review<br/>Quarterly/Annual]
    REVIEW --> START

    style START fill:#1565C0,stroke:#0D47A1,stroke-width:3px,color:#fff
    style CRITICAL fill:#D32F2F,stroke:#B71C1C,stroke-width:3px,color:#fff
    style HIGH fill:#FF9800,stroke:#F57C00,stroke-width:2px
    style MEDIUM fill:#FFC107,stroke:#FFA000,stroke-width:2px
    style LOW fill:#4CAF50,stroke:#2E7D32,stroke-width:2px,color:#fff
    style MINIMAL fill:#9E9E9E,stroke:#616161,stroke-width:1px
    style REGISTER fill:#9C27B0,stroke:#7B1FA2,stroke-width:2px,color:#fff

Likelihood Assessment Framework

Evaluate probability using descriptive categories with quantitative ranges:

Likelihood Assessment Methods

Quantitative Data (Preferred):

# Historical frequency analysis
def calculate_aro(events_last_3_years, trend_factor=1.0):
    """Calculate Annual Rate of Occurrence from historical data"""
    base_aro = sum(events_last_3_years) / 3
    adjusted_aro = base_aro * trend_factor
    return min(adjusted_aro, 0.99)  # Cap at 99%

# Example: 8 incidents in 3 years, increasing trend
aro = calculate_aro([2, 3, 3], trend_factor=1.2)  # = 0.32 (Unlikely)

Qualitative Assessment (When Data Limited):

• Industry benchmarks (DBIR, ENISA Threat Landscape)
• Expert judgment from security team
• Peer comparison with similar organizations
• Threat intelligence feeds

Impact Assessment Framework

Evaluate business impact across multiple dimensions:

Impact Score Mapping

• Catastrophic = 6
• Critical = 5
• High = 4
• Moderate = 3
• Low = 2
• Minimal = 1

Risk Score Calculation

Formula: Risk Score = Likelihood (midpoint %) × Impact Score (1-6) × 100

Calculation Examples

Example 1: Data Breach Risk

• Likelihood: Unlikely (30% midpoint)
• Impact: Critical (5)
• Risk Score: 0.30 × 5 × 100 = 150 → 🟡 Medium Risk

Example 2: DDoS Attack Risk

• Likelihood: Possible (50% midpoint)
• Impact: High (4)
• Risk Score: 0.50 × 4 × 100 = 200 → 🟠 High Risk

Example 3: Ransomware Risk

• Likelihood: Likely (70% midpoint)
• Impact: Catastrophic (6)
• Risk Score: 0.70 × 6 × 100 = 420 → 🔴 Critical Risk

Risk Level Categories

Financial Risk Analysis

Single Loss Expectancy (SLE)

Formula: SLE = Asset Value × Exposure Factor

Asset Value Categories:

Exposure Factor Guidelines:

Annual Loss Expectancy (ALE)

Formula: ALE = SLE × ARO

Example Calculation:

# Ransomware attack on CIA Platform
asset_value = 200000  # €200K (Mission Critical)
exposure_factor = 0.9  # 90% loss (Complete Loss)
aro = 0.7  # 70% (Likely based on industry data)

sle = asset_value * exposure_factor  # €180K
ale = sle * aro  # €126K annually

Value at Risk (VaR) Framework

Formula: VaR = Impact (€) × Probability × Confidence Factor × Time Horizon

VaR Risk Categories:

Risk Treatment Decision Matrix

graph TB
    RISK[📊 Risk Identified<br/>with Score] --> EVAL{Risk Level?}

    EVAL -->|Critical/High<br/>400-600, 200-399| HIGH_TREAT[🎯 Treatment Required]
    EVAL -->|Medium<br/>100-199| MED_TREAT[⚖️ Treatment Evaluation]
    EVAL -->|Low/Minimal<br/>1-99| LOW_TREAT[✅ Consider Acceptance]

    HIGH_TREAT --> OPTIONS1[Treatment Options]
    MED_TREAT --> OPTIONS2[Treatment Options]
    LOW_TREAT --> ACCEPT_DIRECT[Accept Risk<br/>Document in Risk Register]

    OPTIONS1 --> MITIGATE1[🛡️ Mitigate<br/>Implement controls]
    OPTIONS1 --> TRANSFER1[🤝 Transfer<br/>Insurance/Outsource]
    OPTIONS1 --> AVOID1[🚫 Avoid<br/>Eliminate activity]

    OPTIONS2 --> MITIGATE2[🛡️ Mitigate<br/>Cost-benefit analysis]
    OPTIONS2 --> ACCEPT2[📋 Accept<br/>Document rationale]

    MITIGATE1 --> COST_BENEFIT{Control Cost<br/>vs ALE?}
    TRANSFER1 --> COST_BENEFIT
    MITIGATE2 --> COST_BENEFIT

    COST_BENEFIT -->|Control < ALE| IMPLEMENT[✅ Implement Control]
    COST_BENEFIT -->|Control > ALE| ACCEPT_COST[📋 Accept Risk<br/>Document decision]

    AVOID1 --> BUSINESS{Business<br/>Impact?}
    BUSINESS -->|Acceptable| ELIMINATE[🚫 Eliminate Risk]
    BUSINESS -->|Unacceptable| FIND_ALT[🔄 Find Alternative]

    IMPLEMENT --> RESIDUAL[📉 Residual Risk<br/>Assessment]
    ACCEPT2 --> REGISTER[📊 Risk Register]
    ACCEPT_COST --> REGISTER
    ACCEPT_DIRECT --> REGISTER
    ELIMINATE --> REGISTER

    RESIDUAL --> REEVAL{Still<br/>High/Critical?}
    REEVAL -->|Yes| ADDITIONAL[Additional Controls<br/>Required]
    REEVAL -->|No| REGISTER

    ADDITIONAL --> COST_BENEFIT

    style RISK fill:#1565C0,stroke:#0D47A1,stroke-width:3px,color:#fff
    style HIGH_TREAT fill:#D32F2F,stroke:#B71C1C,stroke-width:3px,color:#fff
    style MED_TREAT fill:#FF9800,stroke:#F57C00,stroke-width:2px
    style IMPLEMENT fill:#4CAF50,stroke:#2E7D32,stroke-width:2px,color:#fff
    style REGISTER fill:#9C27B0,stroke:#7B1FA2,stroke-width:2px,color:#fff

Cost-Benefit Analysis Formula

Control Value = ALE (Before) - ALE (After) - Control Cost

def control_roi(ale_before, ale_after, control_cost_annual):
    """Calculate return on investment for security control"""
    annual_benefit = ale_before - ale_after
    net_benefit = annual_benefit - control_cost_annual
    roi_percentage = (net_benefit / control_cost_annual) * 100
    return {
        'annual_benefit': annual_benefit,
        'net_benefit': net_benefit,
        'roi_percentage': roi_percentage,
        'recommendation': 'Implement' if net_benefit > 0 else 'Reject'
    }

# Example: MFA implementation
result = control_roi(
    ale_before=126000,  # €126K ransomware risk
    ale_after=12600,    # 90% reduction
    control_cost_annual=5000  # €5K/year for MFA
)
# Result: €108.4K net benefit, 2068% ROI → Implement

Risk Assessment Templates

Template 1: Comprehensive Risk Assessment

# Risk Assessment: [Risk Name]

**Risk ID:** RSK-2025-XXX
**Assessment Date:** 2025-01-XX
**Assessor:** [Name/Role]
**Status:** Open/Mitigated/Accepted/Closed

## Risk Description
Brief description of the risk scenario.

## Asset Information
- **Primary Asset:** [Asset name]
- **Asset Value:** €X
- **Classification:** [Confidentiality/Integrity/Availability levels]

## Threat & Vulnerability
- **Threat Actor:** [Who/what causes the risk]
- **Threat Motivation:** [Why would they exploit this]
- **Vulnerability:** [What weakness enables exploitation]
- **Attack Vector:** [How the attack occurs]

## Likelihood Assessment
- **Category:** [Exceptional/Rare/Unlikely/Possible/Likely/Almost Certain]
- **Probability:** X%
- **ARO:** X.XX
- **Evidence:** [Historical data, industry benchmarks, expert judgment]

## Impact Assessment
- **Financial:** €X (Category: [Minimal/Low/Moderate/High/Critical/Catastrophic])
- **Operational:** [Description]
- **Reputational:** [Description]
- **Regulatory:** [Description]
- **Impact Score:** X (1-6)

## Risk Calculation
- **Risk Score:** [Probability × Impact × 100] = XXX
- **Risk Level:** 🔴/🟠/🟡/🟢/⚪ [Critical/High/Medium/Low/Minimal]

## Financial Analysis
- **Asset Value:** €X
- **Exposure Factor:** X.X
- **SLE:** €X
- **ALE:** €X

## Current Controls
- [Existing control 1]
- [Existing control 2]

## Recommended Treatment
- **Strategy:** Mitigate/Transfer/Avoid/Accept
- **Proposed Controls:** [List controls]
- **Control Cost:** €X annually
- **Residual Risk Score:** XXX → [Risk Level]
- **Cost-Benefit:** Net benefit €X, ROI X%
- **Recommendation:** Implement/Reject

## Approval
- **Risk Owner:** [Name/Role]
- **Approval Date:** 2025-XX-XX
- **Review Date:** 2025-XX-XX

Template 2: Quick Risk Matrix

Integration with Classification Framework

Align risk assessments with Classification Framework:

CIA Triad Mapping

Confidentiality Impact:

• Very High (C5) → Catastrophic financial impact
• High (C4) → Critical financial impact
• Moderate (C3) → High financial impact
• Low (C2) → Moderate financial impact
• Minimal (C1) → Low financial impact

Integrity Impact:

• Critical (I5) → Catastrophic operational impact
• High (I4) → Critical operational impact
• Moderate (I3) → High operational impact
• Low (I2) → Moderate operational impact
• Minimal (I1) → Low operational impact

Availability Impact:

• Mission Critical (A5) → Catastrophic business impact
• High (A4) → Critical business impact
• Moderate (A3) → High business impact
• Low (A2) → Moderate business impact
• Minimal (A1) → Low business impact

Practical Examples

Example 1: CIA Platform Ransomware Risk

Risk Assessment:

risk_id: "RSK-2025-001"
risk_name: "Ransomware attack on CIA Platform"
asset: "CIA Platform (Production)"
asset_value: 200000  # €200K

likelihood:
  category: "Likely"
  probability: 0.70
  aro: 0.70
  evidence: "Industry data (DBIR 2024), phishing susceptibility"

impact:
  financial: 180000  # €180K recovery costs
  operational: "72-hour downtime"
  reputational: "National media coverage"
  regulatory: "GDPR breach notification required"
  category: "Catastrophic"
  score: 6

risk_score: 420  # 0.70 × 6 × 100
risk_level: "Critical"

financial_analysis:
  sle: 180000  # €200K × 0.9
  ale: 126000  # €180K × 0.70

current_controls:
  - "Firewall"
  - "Antivirus"
  - "User awareness training"

proposed_treatment:
  strategy: "Mitigate"
  controls:
    - "Multi-factor authentication (MFA)"
    - "Endpoint detection and response (EDR)"
    - "Immutable backups (3-2-1 rule)"
    - "Email security gateway"
  control_cost_annual: 15000  # €15K
  residual_likelihood: 0.07  # 90% reduction
  residual_risk_score: 42  # 0.07 × 6 × 100
  residual_risk_level: "Minimal"

cost_benefit:
  ale_reduction: 113400  # €126K - €12.6K
  net_benefit: 98400  # €113.4K - €15K
  roi: 656  # 656% ROI
  recommendation: "IMPLEMENT IMMEDIATELY"

approval:
  risk_owner: "CEO"
  approval_date: "2025-01-25"
  next_review: "2025-04-25"

Example 2: Black Trigram No Authentication Risk

Risk Assessment:

risk_id: "RSK-2025-015"
risk_name: "No authentication system risk"
asset: "Black Trigram Gaming Platform"
asset_value: 10000  # €10K

likelihood:
  category: "Rare"
  probability: 0.12
  aro: 0.12
  evidence: "No user accounts, public content only"

impact:
  financial: 500  # €500 reputation recovery
  operational: "Minimal—frontend only"
  reputational: "Limited local impact"
  regulatory: "None—no personal data"
  category: "Low"
  score: 2

risk_score: 24  # 0.12 × 2 × 100
risk_level: "Minimal"

financial_analysis:
  sle: 5000  # €10K × 0.5 (moderate exposure)
  ale: 600  # €5K × 0.12

treatment:
  strategy: "Accept"
  rationale: "Low confidentiality classification. All content is public educational material. No user-specific operations."
  controls_considered:
    - "Authentication system: €8K/year"
    - "Cost-benefit: Negative ROI (€7.4K loss)"
  residual_risk: "Same as inherent risk"

risk_acceptance:
  documented_in: "Risk_Register.md"
  approved_by: "CEO"
  review_frequency: "Annual"
  trigger_conditions:
    - "Introduction of user accounts"
    - "Processing of personal data"
    - "User-generated content features"

Compliance Mapping

Standards & Policy References

Core Hack23 ISMS Policies:

• Risk Assessment Methodology - Quantitative framework
• Risk Register - Live risk tracking
• Classification Framework - Impact assessment
• Asset Register - Asset valuation
• Threat Modeling - Threat identification

All Hack23 ISMS Policies: https://github.com/Hack23/ISMS-PUBLIC