Cloud access security broker (CASB)

Cloud Access Security Broker (CASB) Buying Guide

Cloud Access Security Brokers (CASBs) are on-premises or cloud-based software that sit between cloud service users and cloud applications, monitoring all activity and enforcing security policies. As organizations increasingly adopt multiple SaaS, PaaS, and IaaS platforms, a CASB becomes critical for extending enterprise security controls to the cloud, ensuring compliance, and preventing data breaches.

What Does a CASB Do?

A CASB acts as a gatekeeper for cloud services, providing a single point of enforcement for security policies across various cloud environments. Its core functions include:

• Visibility: Discovering all cloud applications (sanctioned and unsanctioned), users, and data flowing between them. This includes identifying "shadow IT."
• Data Security: Protecting sensitive data in the cloud through encryption, data loss prevention (DLP), and contextual access control.
• Threat Protection: Identifying and mitigating sophisticated threats, malware, and anomalous user behavior indicative of account compromise within cloud applications.
• Compliance: Helping organizations meet regulatory compliance requirements (e.g., GDPR, HIPAA, PCI DSS) by enforcing data residency, access controls, and auditing capabilities in the cloud.

Key Features to Evaluate

When selecting a CASB, prioritize these critical features:

• Discovery & Risk Assessment:
  • Shadow IT Discovery: Automatic identification of all cloud services accessed by users, including unsanctioned applications.
  • Risk Scoring: Granular risk assessment for each discovered cloud application (e.g., based on security certifications, data privacy policies, and terms of service).
• Data Loss Prevention (DLP):
  • Content-Aware DLP: Sophisticated scanning for sensitive data (e.g., PII, credit card numbers, intellectual property) within data at rest and in transit in cloud applications.
  • Policy Enforcement: Real-time blocking, quarantining, or encryption of data uploads/downloads violating policies.
  • Contextual DLP: Policies based on user, device, location, and application.
• Access Control:
  • Adaptive Access Control: Dynamic access decisions based on user identity, device posture, location, and application risk.
  • Single Sign-On (SSO) Integration: Seamless integration with existing identity providers (e.g., Okta, Azure AD) for unified authentication.
• Threat Protection:
  • Malware Detection: Scanning of files uploaded to or downloaded from cloud applications for malicious content.
  • User Behavior Analytics (UBA): Detection of anomalous user activities (e.g., unusual login locations, excessive downloads) indicating compromised accounts.
  • Cloud Security Posture Management (CSPM): For IaaS/PaaS CASBs, continuous monitoring of cloud configurations against best practices and compliance benchmarks.
• Encryption & Tokenization:
  • Cloud Data Encryption: Encrypting sensitive data before it resides in the cloud, often with customer-managed keys.
  • Format-Preserving Tokenization (FPT): Replacing sensitive data with non-sensitive tokens while preserving usability.
• API vs. Proxy Deployment:
  • API-based: Connects directly with cloud service APIs for discovery, data security, and policy enforcement on data at rest and in transit. Offers deep introspection but less real-time blocking.
  • Proxy-based (Forward/Reverse): Intercepts traffic between users and cloud services for real-time visibility, blocking, and policy enforcement. Can cause latency. Many modern CASBs offer integrated or hybrid approaches.

Use Cases

• Shadow IT Management: Discover and control unsanctioned cloud applications to reduce risk exposure.
• SaaS DLP: Prevent sensitive corporate data from being shared inappropriately via sanctioned SaaS applications (e.g., Microsoft 365, Salesforce).
• Compliance Adherence: Ensure data stored in cloud services meets regulatory requirements (e.g., GDPR for EU data residency, HIPAA for healthcare data).
• Securing Remote Work: Enforce consistent security policies for all users accessing cloud applications from any location or device.
• Cloud-to-Cloud DLP: Prevent data leakage between different cloud services.
• IaaS/PaaS Security Posture: Continuously monitor and remediate misconfigurations in AWS, Azure, or GCP environments.

Implementation Considerations

• Integration with Existing Infrastructure: Assess compatibility with your current identity providers, SIEM, and endpoint security solutions.
• Deployment Model: Determine if an API-only, proxy-only, or hybrid deployment best fits your architecture and security requirements.
• Scope of Coverage: Identify which specific cloud applications (SaaS, IaaS, PaaS) need CASB protection.
• Performance Impact: Evaluate potential latency introduced by proxy-based deployments, especially for global users.
• Scalability: Ensure the solution can scale with your organization's growing cloud footprint and user base.
• Management Overhead: Consider the ease of policy creation, dashboard usability, and reporting capabilities.

Pricing Models

CASB pricing typically follows these models:

• Per User: Most common for SaaS CASBs, charging based on the number of active users accessing protected cloud applications.
• Per Application: Less common, but some vendors may charge per cloud application instance secured.
• Data Volume/Traffic: For IaaS/PaaS protection, some models may consider the volume of data processed or network traffic monitored.
• Tiered Plans: Many vendors offer different tiers based on features, support levels, and included cloud service connectors.
• Consumption-Based: For IaaS/PaaS security aspects, pricing might relate to the resources monitored (e.g., number of VMs, storage buckets).

Selection Criteria

1. Comprehensive Cloud Coverage: Does it support all the critical SaaS, IaaS, and PaaS providers you currently use or plan to use?
2. Granular Policy Control: Can you define highly specific security policies based on user, device, location, application, and content?
3. Advanced DLP Capabilities: Evaluate the accuracy of the DLP engine, its ability to detect various data types, and supported remediation actions.
4. Effective Threat Protection: Look for robust UBA and malware detection capabilities.
5. Deployment Flexibility: Choose a solution that allows for a deployment model (API, proxy, hybrid) that aligns with your network architecture and risk tolerance.
6. Ease of Integration: Assess how well it integrates with your existing security ecosystem (IDP, SIEM, EDR).
7. Reporting and Analytics: Clear dashboards, detailed logs, and customizable reports are essential for demonstrating compliance and identifying risks.
8. Vendor Reputation & Support: Research vendor stability, customer reviews, and available technical support.
9. Scalability and Performance: Ensure the CASB can handle your current and future cloud usage without significant performance degradation.
10. Cost-Effectiveness: Compare features and pricing across vendors to find a solution that offers the best value for your specific needs.