# Scoring Comparison: Our Approach vs AWS Config Conformance Packs

## Overview

This document compares our weighted scoring methodology with AWS Config's Conformance Pack approach.

## AWS Config Conformance Pack Approach

### Formula
```
Compliance Score = Compliant Rule-Resources / Total Rule-Resources
```

### Characteristics
- **Simple percentage** - No weighting applied
- **Flat structure** - All rules treated equally
- **Resource-centric** - Counts individual rule-resource combinations
- **No prioritization** - Critical and minor rules have equal impact

### Example Calculation
```
Rule 1: 90/100 resources compliant
Rule 2: 50/50 resources compliant
Rule 3: 10/50 resources compliant

Total: (90 + 50 + 10) / (100 + 50 + 50)
     = 150 / 200
     = 75% compliance
```

## Our Weighted Approach

### Formula
```
Overall Score = Σ(IG Score × IG Weight) / Σ(IG Weights)
  where IG Score = Σ(Control Score × Control Weight) / Σ(Control Weights)
  where Control Score = Compliant Resources / Total Resources
```

### Characteristics
- **Weighted average** - Critical controls have more impact
- **Hierarchical structure** - Controls → IGs → Overall
- **Security-centric** - Prioritizes critical security controls
- **Maturity-aware** - Advanced IGs (IG2/IG3) weighted higher

### Example Calculation
```
Control 1 (weight 1.0): 90/100 = 90%
Control 2 (weight 1.5): 50/50 = 100%
Control 3 (weight 1.0): 10/50 = 20%

Weighted: (90×1.0 + 100×1.5 + 20×1.0) / (1.0 + 1.5 + 1.0)
        = (90 + 150 + 20) / 3.5
        = 260 / 3.5
        = 74.3% compliance
```

## Side-by-Side Comparison

| Aspect | AWS Config Conformance Pack | Our Weighted Approach |
|--------|----------------------------|----------------------|
| **Formula** | Simple average | Weighted average |
| **Structure** | Flat (all rules equal) | Hierarchical (Controls → IGs → Overall) |
| **Weighting** | None | Control weights + IG weights |
| **Prioritization** | No | Yes (critical controls weighted higher) |
| **Maturity Levels** | Not considered | IG1/IG2/IG3 weighted differently |
| **Complexity** | Low | Medium |
| **Customization** | Limited | Highly customizable |
| **Focus** | Resource compliance | Security posture |

## Real-World Impact Comparison

### Scenario 1: Critical Control Failure

**Setup:**
- 3 controls assessed
- Control 1 (Asset Inventory, weight 1.0): 90/100 = 90%
- Control 2 (Encryption at Rest, weight 1.4): 10/100 = 10% ⚠️ CRITICAL
- Control 3 (Logging, weight 1.2): 80/100 = 80%

**AWS Config Approach:**
```
Score = (90 + 10 + 80) / (100 + 100 + 100)
      = 180 / 300
      = 60% compliance
```

**Our Weighted Approach:**
```
Score = (90×1.0 + 10×1.4 + 80×1.2) / (1.0 + 1.4 + 1.2)
      = (90 + 14 + 96) / 3.6
      = 200 / 3.6
      = 55.6% compliance
```

**Analysis:**
- Our approach scores **4.4% lower** because encryption (critical) is weighted higher
- This better reflects the **security risk** of poor encryption compliance
- AWS Config treats encryption failure same as asset inventory issues

### Scenario 2: Minor Control Failure

**Setup:**
- 3 controls assessed
- Control 1 (Asset Inventory, weight 1.0): 10/100 = 10% ⚠️ MINOR
- Control 2 (Encryption at Rest, weight 1.4): 90/100 = 90%
- Control 3 (Logging, weight 1.2): 80/100 = 80%

**AWS Config Approach:**
```
Score = (10 + 90 + 80) / (100 + 100 + 100)
      = 180 / 300
      = 60% compliance
```

**Our Weighted Approach:**
```
Score = (10×1.0 + 90×1.4 + 80×1.2) / (1.0 + 1.4 + 1.2)
      = (10 + 126 + 96) / 3.6
      = 232 / 3.6
      = 64.4% compliance
```

**Analysis:**
- Our approach scores **4.4% higher** because critical controls (encryption) are compliant
- This better reflects the **actual security posture** despite asset inventory issues
- AWS Config penalizes equally regardless of control importance

### Scenario 3: Multiple Implementation Groups

**Setup:**
- IG1: 85% compliance (74 controls)
- IG2: 75% compliance (58 additional controls)
- IG3: 60% compliance (13 additional controls)

**AWS Config Approach:**
```
All rules treated equally:
Score = (85 + 75 + 60) / 3
      = 73.3% compliance
```

**Our Weighted Approach:**
```
Score = (85×1.0 + 75×1.5 + 60×2.0) / (1.0 + 1.5 + 2.0)
      = (85 + 112.5 + 120) / 4.5
      = 317.5 / 4.5
      = 70.6% compliance
```

**Analysis:**
- Our approach scores **2.7% lower** because IG3 (advanced security) is weighted higher
- This reflects that **advanced security failures** are more concerning
- AWS Config doesn't distinguish between basic and advanced security

## Key Differences Explained

### 1. Security Prioritization

**AWS Config:**
- Treats all rules equally
- 100 non-compliant S3 buckets = 100 non-compliant IAM users
- No distinction between critical and minor issues

**Our Approach:**
- Critical controls (encryption, access control) weighted higher
- 100 non-encrypted databases > 100 untagged EC2 instances
- Reflects actual security risk

### 2. Maturity Recognition

**AWS Config:**
- No concept of security maturity levels
- Basic and advanced controls treated the same

**Our Approach:**
- IG1 (Essential) = baseline weight
- IG2 (Enhanced) = 1.5x weight
- IG3 (Advanced) = 2x weight
- Encourages progression to higher security maturity

### 3. Resource Distribution Impact

**AWS Config:**
- Heavily influenced by resource count
- 1 rule with 1000 resources dominates score
- Can mask issues in rules with fewer resources

**Our Approach:**
- Each control scored independently first
- Then weighted and averaged
- Prevents resource count from dominating
- Better reflects control-level compliance

### 4. Actionable Insights

**AWS Config:**
- Simple percentage
- Doesn't indicate which areas need focus
- All non-compliance treated equally

**Our Approach:**
- Identifies high-priority remediation areas
- Weights guide where to focus effort
- Risk areas highlighted based on criticality

## Practical Examples

### Example 1: Encryption Compliance

**Scenario:** Organization has poor encryption but good asset management

| Control | Resources | Compliant | AWS Config Impact | Our Impact |
|---------|-----------|-----------|-------------------|------------|
| Asset Inventory (1.0) | 1000 | 950 (95%) | 950/1000 | 95% × 1.0 |
| Encryption at Rest (1.4) | 100 | 20 (20%) | 20/100 | 20% × 1.4 |

**AWS Config Score:**
```
(950 + 20) / (1000 + 100) = 970/1100 = 88.2%
```

**Our Score:**
```
(95×1.0 + 20×1.4) / (1.0 + 1.4) = (95 + 28) / 2.4 = 51.3%
```

**Difference:** -36.9%

**Why?** Our approach correctly identifies this as a **critical security issue** despite high resource compliance in less critical areas.

### Example 2: Balanced Compliance

**Scenario:** Organization has consistent compliance across all controls

| Control | Resources | Compliant | Compliance % |
|---------|-----------|-----------|--------------|
| Control 1 (1.0) | 100 | 80 | 80% |
| Control 2 (1.5) | 100 | 80 | 80% |
| Control 3 (1.2) | 100 | 80 | 80% |

**AWS Config Score:**
```
(80 + 80 + 80) / (100 + 100 + 100) = 240/300 = 80%
```

**Our Score:**
```
(80×1.0 + 80×1.5 + 80×1.2) / (1.0 + 1.5 + 1.2) = (80 + 120 + 96) / 3.7 = 80%
```

**Difference:** 0%

**Why?** When compliance is **consistent across controls**, both approaches yield the same result.

### Example 3: Resource Count Skew

**Scenario:** One rule has many resources, others have few

| Control | Resources | Compliant | Compliance % |
|---------|-----------|-----------|--------------|
| Control 1 (1.0) | 1000 | 900 | 90% |
| Control 2 (1.5) | 10 | 2 | 20% |
| Control 3 (1.2) | 10 | 2 | 20% |

**AWS Config Score:**
```
(900 + 2 + 2) / (1000 + 10 + 10) = 904/1020 = 88.6%
```

**Our Score:**
```
(90×1.0 + 20×1.5 + 20×1.2) / (1.0 + 1.5 + 1.2) = (90 + 30 + 24) / 3.7 = 38.9%
```

**Difference:** -49.7%

**Why?** AWS Config is **dominated by the high resource count** in Control 1. Our approach treats each control equally, revealing the **poor compliance in critical areas**.

## When Each Approach is Better

### AWS Config Approach is Better When:

1. **Simplicity is paramount** - Easy to understand and explain
2. **All rules are equally important** - No need for prioritization
3. **Resource-level tracking** - Focus on individual resource compliance
4. **Regulatory compliance** - Simple pass/fail requirements
5. **Audit purposes** - Straightforward percentage for auditors

### Our Weighted Approach is Better When:

1. **Security prioritization matters** - Critical controls should have more impact
2. **Risk-based decision making** - Focus on highest-risk areas
3. **Maturity progression** - Encouraging advancement through IG levels
4. **Executive reporting** - Reflects actual security posture
5. **Remediation planning** - Guides where to focus effort
6. **Resource optimization** - Prevents resource count from dominating

## Conversion Between Approaches

### Converting Our Score to AWS Config Style

To get an "unweighted" score similar to AWS Config:

```python
# Sum all compliant resources across all controls
total_compliant = sum(control.compliant_resources for control in controls)

# Sum all total resources across all controls
total_resources = sum(control.total_resources for control in controls)

# Calculate simple percentage
aws_config_style_score = (total_compliant / total_resources) * 100
```

### Converting AWS Config to Our Style

To add weighting to AWS Config scores:

```python
# Apply control weights to each rule's compliance
weighted_scores = []
for rule in rules:
    rule_compliance = rule.compliant / rule.total
    weight = get_control_weight(rule.control_id)
    weighted_scores.append(rule_compliance * weight)

# Calculate weighted average
our_style_score = sum(weighted_scores) / sum(weights)
```

## Recommendations

### Use AWS Config Approach If:
- You need simple, auditable compliance reporting
- All controls have equal business importance
- You're reporting to non-technical stakeholders
- Regulatory requirements specify simple percentage

### Use Our Weighted Approach If:
- You need risk-based security prioritization
- Critical controls should influence score more
- You're managing security maturity progression
- You need actionable remediation guidance
- You want to prevent resource count skew

### Use Both Approaches:
- Report **AWS Config style** for auditors and compliance
- Use **weighted approach** for security decision-making
- Track both metrics over time for comprehensive view

## Summary Table

| Metric | AWS Config | Our Approach | Difference |
|--------|-----------|--------------|------------|
| **Complexity** | Low | Medium | More complex but more insightful |
| **Accuracy** | Resource-level | Security-level | Better reflects security posture |
| **Actionability** | Limited | High | Clear prioritization guidance |
| **Customization** | None | High | Adaptable to organization needs |
| **Audit-friendly** | Very | Moderate | May need explanation |
| **Risk-awareness** | No | Yes | Reflects actual security risk |

## Conclusion

**AWS Config's approach** is simpler and more straightforward - it counts compliant resources and divides by total resources. This works well for basic compliance tracking but doesn't reflect security priorities.

**Our weighted approach** adds complexity but provides **better security insights** by:
1. Prioritizing critical controls (encryption, access control)
2. Recognizing security maturity levels (IG1/IG2/IG3)
3. Preventing resource count from dominating scores
4. Providing actionable remediation guidance

**Best Practice:** Use both approaches:
- **AWS Config style** for compliance reporting and audits
- **Weighted approach** for security decision-making and prioritization

---

**Recommendation:** Consider adding an "unweighted score" output option to provide both perspectives to users.
