Cloud access security broker

PolicyEngine { private policies: CASBPolicy[];

constructor(policies: CASBPolicy[]) { this.policies = policies; }

evaluate(context: CASBContext, resource: CASBResource): { decision: string; policyId?: string; riskScore: number } { // Calculate aggregate risk score const riskScore = this.calculateRiskScore(context);

// Evaluate policies in priority order
for (const policy of this.policies) {
  if (policy.conditions(context, resource)) {
    if (riskScore >= policy.riskThreshold) {
      return { decision: policy.action, policyId: policy.id, riskScore };
    }
  }
}

// Default deny for high risk if no policy matches
if (riskScore > 80) {
  return { decision: 'deny', riskScore };
}

return { decision: 'allow', riskScore };

}

private calculateRiskScore(context: CASBContext): number { let score = 0; score += context.deviceRiskScore * 0.4; score += context.sessionRisk === 'high' ? 30 : context.sessionRisk === 'medium' ? 15 : 0; score += context.ipReputation === 'malicious' ? 40 : context.ipReputation === 'suspicious' ? 20 : 0; return Math.min(score, 100); } }

// Example Usage const policies: CASBPolicy[] = [ { id: 'POL-001', name: 'Block External Sharing of Restricted Data', conditions: (ctx, res) => res.dataClassification === 'restricted' && res.action === 'share' && res.recipientDomain !== 'company.com', action: 'deny', riskThreshold: 0 }, { id: 'POL-002', name: 'Require MFA for High Risk Sessions', conditions: (ctx) => ctx.sessionRisk === 'high', action: 'mfa_challenge', riskThreshold: 50 } ];

const engine = new CASBPolicyEngine(policies);

const requestContext: CASBContext = { userId: 'user@company.com', deviceId: 'dev-123', deviceRiskScore: 20, geoLocation: 'US', ipReputation: 'clean', sessionRisk: 'medium' };

const resourceRequest: CASBResource = { appId: 'salesforce', dataClassification: 'restricted', action: 'share', recipientDomain: 'competitor.com' };

const result = engine.evaluate(requestContext, resourceRequest); console.log(Decision: ${result.decision}, Policy: ${result.policyId}, Risk: ${result.riskScore}); // Output: Decision: deny, Policy: POL-001, Risk: 35

### Architecture Decisions

*   **Tokenization vs. Encryption:** For data protection, tokenization preserves data format while replacing sensitive values with non-sensitive tokens, allowing legacy systems to function. Encryption provides stronger security but may break application functionality. Use tokenization for fields like credit card numbers within SaaS forms; use encryption for data at rest.
*   **Centralized vs. Distributed PEPs:** Centralized PEPs simplify policy management but create a single point of failure. Distributed PEPs (e.g., agents on endpoints) improve resilience and local decision-making but increase management complexity. Hybrid architectures are recommended for large enterprises.
*   **API Rate Limiting:** API-connected CASBs must implement intelligent polling strategies to avoid hitting SaaS API rate limits. Use incremental syncs and event-driven architectures where supported by the SaaS provider.

## Pitfall Guide

1.  **Ignoring API Rate Limits:** Aggressive polling of SaaS APIs can trigger rate limiting, causing data gaps and alert fatigue. **Best Practice:** Implement exponential backoff, use webhooks for event-driven updates, and prioritize critical data syncs.
2.  **Over-Blocking Productivity:** Strict policies that block legitimate user actions lead to shadow IT workarounds. **Best Practice:** Start with "monitor-only" mode, analyze user behavior, and gradually tighten policies based on risk data. Communicate changes to users.
3.  **Misconfigured Certificate Trust:** Forward proxy deployments require SSL/TLS inspection. If certificate pinning is not handled correctly, applications may fail. **Best Practice:** Deploy root CA certificates via MDM, maintain a whitelist of certificate-pinned apps, and test thoroughly before full deployment.
4.  **Lack of Identity Context:** Policies based solely on IP addresses or basic attributes are ineffective against compromised credentials. **Best Practice:** Integrate deeply with IdP and EDR solutions to include device posture, user risk scores, and behavioral analytics in policy decisions.
5.  **Static Policy Management:** Cloud environments change rapidly. Static policies become obsolete. **Best Practice:** Automate policy reviews, use risk-based adaptive policies, and integrate with threat intelligence feeds for dynamic updates.
6.  **Data Residency Non-Compliance:** CASB policies may not account for data sovereignty requirements. **Best Practice:** Map data flows to geographic regions, enforce location-based access controls, and audit data storage locations regularly.
7.  **Alert Fatigue:** Excessive alerts from misconfigured policies overwhelm security teams. **Best Practice:** Tune alert thresholds, aggregate related events, and prioritize alerts based on business impact and risk score.

## Production Bundle

### Action Checklist

- [ ] **Audit SaaS Inventory:** Run automated discovery to identify all sanctioned and unsanctioned cloud applications.
- [ ] **Define Data Classification Schema:** Establish clear labels for data sensitivity (Public, Internal, Confidential, Restricted) and map them to CASB policies.
- [ ] **Select Deployment Modes:** Choose API-connected for broad visibility and proxy for high-risk real-time enforcement based on risk assessment.
- [ ] **Implement DLP Policies:** Configure data loss prevention rules for sensitive data types, starting with monitor mode and transitioning to block.
- [ ] **Configure Alerting Thresholds:** Set risk-based alerting to minimize noise and focus on high-impact events.
- [ ] **Test Incident Response:** Simulate breach scenarios to validate CASB detection and response capabilities.
- [ ] **Review and Tune Quarterly:** Conduct regular policy reviews to adapt to changing business needs and threat landscape.

### Decision Matrix

| Scenario | Recommended Approach | Why | Cost Impact |
|----------|---------------------|-----|-------------|
| **High-Growth Startup** | API-First Cloud CASB | Rapid deployment, low operational overhead, scales with SaaS adoption. | Low/Medium |
| **Regulated Finance** | Hybrid Proxy + API + Tokenization | Deep inspection, strict compliance, data protection for sensitive records. | High |
| **Remote-First Global** | SASE/Zero Trust Integration | Unified security for mobile users, consistent policy enforcement regardless of location. | Medium/High |
| **Legacy App Modernization** | Reverse Proxy + API | Secure access to legacy apps during migration, gradual policy enforcement. | Medium |

### Configuration Template

Below is a JSON configuration template for defining CASB policies. This structure supports granular control over access, data protection, and threat detection.

```json
{
  "policy_id": "CASB-POL-2024-001",
  "name": "Restrict External Sharing of Confidential Data",
  "description": "Blocks sharing of confidential files with external domains and alerts security team.",
  "enabled": true,
  "priority": 100,
  "conditions": {
    "data_classification": ["confidential", "restricted"],
    "action": ["share", "download"],
    "recipient_domain": { "operator": "not_in", "values": ["company.com", "partner.com"] },
    "user_risk_score": { "operator": "lte", "value": 70 }
  },
  "actions": {
    "enforcement": "block",
    "notification": {
      "type": "alert",
      "channels": ["email", "siem"],
      "severity": "high"
    },
    "remediation": {
      "type": "revoke_access",
      "delay_seconds": 300
    }
  },
  "exceptions": [
    {
      "reason": "Executive Approval",
      "condition": { "user_group": ["executives"] },
      "approval_required": true
    }
  ],
  "audit_log": true
}

Quick Start Guide

1. Connect Identity Provider: Integrate your CASB with your IdP (e.g., Okta, Azure AD) to synchronize user identities and group memberships.
2. Enable API Connectors: Activate API connectors for your top 3 critical SaaS applications (e.g., Microsoft 365, Salesforce, Slack) to begin data discovery.
3. Apply Monitor-Only DLP Policy: Deploy a DLP policy in monitor mode for sensitive data types to assess impact without disrupting users.
4. Review Dashboard: Analyze the CASB dashboard after 24 hours to identify shadow IT, misconfigurations, and data exposure risks.
5. Switch to Block: Transition critical policies from monitor to block mode based on risk analysis, and configure alerting for security operations.