Cloud Access Security Broker (CASB): Bridging Security Gaps in the Cloud Era

As organizations increasingly rely on cloud services like Microsoft 365, Google Workspace, Salesforce, and Slack, their traditional security perimeter dissolves. IT teams lose visibility and control over where sensitive data goes, who accesses it, and how it’s shared.

This is where Cloud Access Security Brokers (CASBs) step in — as the control point between users and cloud services.

Whether you’re securing sanctioned SaaS apps or mitigating the risks of shadow IT, CASB is essential for modern cloud security.

What Is a CASB?

A Cloud Access Security Broker (CASB) is a security solution that sits between cloud service consumers and providers to enforce enterprise security, compliance, and governance policies.

CASBs provide visibility, data security, threat protection, and compliance across cloud applications.

They can be deployed in four modes:

• API-based (out-of-band)

• Proxy-based (inline)

• Agent-based

• Log-based (discovery)

Why CASB Is Critical in 2025

• SaaS adoption is exploding: most companies use >100 cloud apps

• Shadow IT is rampant: users bypass IT to use unsanctioned apps

• Sensitive data moves freely in the cloud

• Insider threats and misconfigurations are common

• Regulatory pressure (e.g., GDPR, HIPAA, ISO 27001) demands control

CASBs give security teams the visibility and control they need — without slowing productivity.

Core Capabilities of CASB Platforms

1. Cloud Discovery

   • Identify all cloud apps in use (sanctioned and unsanctioned)

   • Analyze usage patterns and risk profiles

2. Data Security and DLP

   • Scan data in cloud apps for PII, PCI, IP, and more

   • Enforce encryption, redaction, or blocking policies

3. Access Control and Policy Enforcement

   • Set rules based on user, device, location, or app

   • Allow, deny, or quarantine specific behaviors

4. Threat Protection

   • Detect compromised accounts, malware, and risky behaviors

   • Integrate with threat intelligence and UEBA tools

5. Compliance Management

   • Map activity and data handling to frameworks like HIPAA, SOC 2

   • Generate audit reports and policy coverage summaries

CASB Use Cases

• Preventing data exfiltration via cloud apps

• Blocking uploads of confidential files to personal Dropbox or Google Drive

• Enforcing MFA for high-risk cloud activity

• Detecting abnormal login patterns across SaaS platforms

• Applying DLP to Microsoft 365, G Suite, and Slack

Leading CASB Solutions in 2025

1. Microsoft Defender for Cloud Apps (formerly MCAS)

• Deep integration with Microsoft 365 and Azure

• Real-time control and session policies

• Powerful DLP, threat detection, and app governance

• Built-in analytics and shadow IT discovery

2. Netskope CASB

• Inline and API-based protection

• Covers thousands of SaaS apps

• Context-aware policies

• Seamless integration with SWG, ZTNA, and DLP

3. McAfee MVISION Cloud (Skyhigh Security)

• Advanced encryption and tokenization

• Deep forensic analysis and activity logs

• Supports IaaS and PaaS protection

• Compliance rule sets for global regulations

4. Cisco Cloudlock

• Agentless, API-based CASB

• Designed for Google Workspace, Salesforce, Box

• Threat detection using machine learning

• Easy policy customization and enforcement

5. Bitglass (Forcepoint ONE)

• Unified cloud security platform with CASB, SWG, and ZTNA

• Real-time inline protection

• Built-in DLP and malware protection

• Supports managed and unmanaged device scenarios

CASB vs SWG vs ZTNA: What’s the Difference?

Many organizations combine CASB, SWG, and ZTNA under a SASE (Secure Access Service Edge) framework.

Challenges in CASB Implementation

• Too many alerts without proper tuning

• API limits for real-time enforcement

• User resistance to inline proxies

• Blind spots for unmanaged devices

• Shadow IT bypassing controls

To succeed, align CASB rollout with security, IT, and user productivity goals. Start with app discovery, then move to risk-based enforcement.