Cloud Access Security Brokers (CASB): Complete Guide [2025]

What Is a Cloud Access Security Broker (CASB)? 

A cloud access security broker (CASB) acts as an intermediary between cloud service consumers and providers, enforcing security, compliance, and governance. These platforms ensure that the data passing between on-premises and cloud infrastructures is secure, monitored, and compliant with enterprise policies. By deploying a CASB, organizations can adopt cloud services while minimizing risks associated with data breaches and unauthorized access.

CASBs provide a view of cloud usage within an organization, offering insights into user behavior and potential security risks. This visibility enables businesses to implement policies that protect sensitive data, maintain regulatory compliance, and prevent data leakage. As cloud adoption grows, CASBs play a crucial role in ensuring secure cloud operations and addressing the challenges of modern IT environments.

The Four Pillars of CASBs 

Visibility

Visibility is a core function of CASBs, offering insights into the use of cloud services across an organization. These platforms provide logs and analytics about user activities, application usage, and data transfers. This transparency helps organizations identify shadow IT, where employees use unsanctioned cloud services, potentially putting sensitive data at risk. By understanding cloud usage patterns, businesses can manage access, prevent data leaks, and ensure compliance with corporate policies.

CASBs implement visibility by monitoring both sanctioned and unsanctioned applications. They can detect anomalous behavior that might indicate insider threats or compromised accounts. With tools to visualize cloud environments, organizations can remediate risks and make informed decisions about app usage. This capability is essential for maintaining control over cloud services and preventing unauthorized data exposure.

Compliance

CASB solutions help organizations adhere to regulatory requirements. CASBs enforce policies that align with mandates such as GDPR, HIPAA, and PCI DSS, ensuring that data is managed responsibly in the cloud. This is particularly important in industries with strict data protection regulations. A CASB can automate compliance checks, reducing the manual effort involved and the potential for human error.

Efficient compliance management in cloud environments minimizes the risk of regulatory fines and enhances an organization’s reputation. CASBs offer tools for continuous monitoring of data movement and usage, ensuring that all activities meet compliance standards. Reporting features allow organizations to produce audit trails, demonstrating compliance efforts to regulators and stakeholders.

Data Security

CASBs promote data security by applying encryption methods, access controls, and security policies to safeguard data as it moves to and from cloud services. By enforcing data loss prevention (DLP) strategies, CASBs mitigate exposure risks whether data is stored at rest, in transit, or being processed.

The CASB’s role in data security extends to identifying and mitigating threats from malicious insiders and external attackers. By monitoring user behavior and employing threat detection techniques, CASBs prevent data exfiltration and ensure only authorized users can access business-critical information. This data protection framework enhances security posture and supports the secure adoption of diverse cloud services.

Threat Protection

Threat protection is a central feature of CASBs, offering defenses against various security threats in cloud environments. CASBs provide real-time threat assessments using algorithms and anomaly detection to identify potential risks. They can intercept malicious payloads and prevent compromised credentials from being used in attacks.

CASBs also integrate with existing enterprise security systems, such as firewalls and SIEM tools, to offer a synchronized defense strategy. This integration ensures that organizations benefit from threat intelligence and corrective actions, allowing for swift responses to incidents. By providing layered threat protection, CASBs help organizations maintain secure cloud environments and reduce risk exposure.

How Does a CASB Work? 

1. Discovery

Discovery is the initial step in the CASB process, identifying all cloud services and applications in use within an organization. This involves detecting both sanctioned apps approved by IT and shadow IT, which consists of unsanctioned apps used without IT’s knowledge. Identifying this usage gives organizations clarity over who is using what and helps address potential security issues that arise from unsanctioned cloud operations.

Automated discovery tools within CASBs scan networks for cloud service usage patterns, helping security teams understand app traffic and user behavior across the network. By categorizing and reporting cloud app usage, CASBs provide an opportunity for organizations to assess risks and enforce access controls. This approach ensures that unsanctioned apps are monitored and, if necessary, blocked or replaced with secure alternatives.

2. Classification

Classification involves grouping data and applications into categories based on sensitivity and risk. CASBs classify data at multiple levels, from highly sensitive business information to less critical data, allowing for tailored security policies. This step ensures that appropriate security measures are applied according to data importance, minimizing the risk of breach.

Effective classification helps organizations prioritize data protection efforts and allocate resources efficiently. CASBs employ automated classification techniques using predefined rules and machine learning to analyze data patterns. This process enables dynamic policy enforcement, ensuring that sensitive information remains secure while enabling flexible and safe collaboration in cloud environments.

3. Remediation

Remediation is the CASB’s ability to respond to identified risks by mitigating threats and enforcing security policies. Once a risk is detected, remediation actions are automatically or manually applied to prevent data breaches and non-compliance. This includes adjusting policies, blocking access, encrypting data, or notifying personnel about security incidents.

CASBs also offer granular policy controls that allow administrators to dictate specific remediation actions based on data sensitivity and risk level. This capability ensures tailored responses to incidents while preserving operational efficiency. By automating remediation processes, organizations can reduce response time to threats, maintaining a secure cloud environment and minimizing business impact.

Tips from the expert

Steve Moore is Vice President and Chief Security Strategist at Exabeam, helping drive solutions for threat detection and advising customers on security programs and breach response. He is the host of the “The New CISO Podcast,” a Forbes Tech Council member, and Co-founder of TEN18 at Exabeam.

In my experience, here are tips that can help you better leverage a Cloud Access Security Broker (CASB):

Leverage user behavior analytics (UBA): Use CASB’s built-in UBA capabilities to monitor deviations in user behavior. Anomalies like sudden data downloads or access from unusual locations can highlight compromised accounts or insider threats early.

Automate remediation with conditional access: Set up automated remediation actions based on risk levels. For example, automatically enforce multi-factor authentication (MFA) or restrict access when the CASB detects high-risk activities, reducing response times during incidents.

Integrate CASB with identity management platforms: Tight integration with identity access management (IAM) tools like SSO (Single Sign-On) or Privileged Access Management (PAM) strengthens identity governance, ensuring that users’ cloud access aligns with role-based policies.

Cross-reference with SIEM and threat intelligence: Integrate CASB with your SIEM and threat intelligence platforms to correlate cloud app activity with broader security events. This cross-referencing helps detect sophisticated attacks, like data exfiltration that combines both on-prem and cloud elements.

Enforce adaptive access controls based on context: Use contextual access controls (such as device type, location, or time of access) in your CASB policies. This ensures flexible, secure access while preventing overly rigid rules that might hinder productivity.

Key Use Cases for CASBs 

Discover All Cloud Apps and Services in Use

CASBs are essential for discovering and monitoring all cloud applications and services used in an organization. Many businesses are unaware of the extent of cloud app usage within their environment, leading to potential security risks from unsanctioned or shadow IT. CASBs help in identifying these applications by providing insights into both sanctioned and unsanctioned apps, facilitating better control over IT resources and data.

The discovery process helps organizations map out cloud service usage, assess associated risks, and implement appropriate security measures. CASBs continuously analyze network traffic to detect any new cloud applications, enabling organizations to address potential security gaps. This ongoing process of discovery and monitoring is crucial for maintaining visibility in cloud environments, ensuring that all activity aligns with enterprise policies and preventing unauthorized data exposure.

Assess Risk and Compliance in Cloud-Based Apps

A significant use case for CASBs is the assessment of risk and compliance in cloud-based applications. By evaluating the security posture of these apps against established benchmarks and regulatory standards, CASBs help maintain compliance with legal and corporate policies. This process involves analyzing app security features, data handling practices, and third-party integrations, ensuring they meet compliance requirements.

CASBs automate risk assessments, providing continuous checks on compliance and offering real-time insights into vulnerabilities. This automated approach reduces the efforts of manual audits and enhances the accuracy of compliance checks. With detailed reports, organizations can quickly identify non-compliance issues and take corrective actions.

Detect New and Risky Cloud Apps

CASBs enable monitoring to detect new, potentially risky cloud applications entering the network environment. This capability is crucial for managing shadow IT and preventing unauthorized apps from compromising data security. Through continuous monitoring, CASBs can pinpoint unusual access patterns or unapproved app usage, triggering alerts and facilitating swift responses to potential threats.

Monitoring allows organizations to enforce security policies more efficiently, ensuring all applications comply with internal standards. CASBs provide administrators with real-time dashboards showing app utilization and risk levels, aiding informed decision-making. By maintaining a view of cloud app usage, CASBs empower organizations to mitigate risks associated with accidental data leaks and malicious activities.

Main Types of CASBs

Inline CASB

Inline CASBs operate within the data path, acting as intermediaries between users and cloud services. These brokers intercept user traffic to apply security measures in real-time, offering immediate threat detection, data encryption, and access control. Inline CASBs provide security by preventing the transmission of sensitive data to unauthorized users or applications before it reaches the cloud service.

One advantage of inline CASBs is their ability to enforce consistent security policies across multiple cloud applications, ensuring that data protection rules are uniformly applied. However, the inline approach may introduce latency or performance issues due to real-time processing. Despite these potential challenges, inline CASBs remain an effective choice for organizations requiring immediate and comprehensive cloud security controls.

API-based CASB

API-based CASBs leverage cloud service provider APIs to monitor user interactions and data transfers. This method allows for non-intrusive security enforcement, providing flexibility and minimal impact on network performance. By extracting data from cloud provider APIs, these CASBs gain insight into application activities and apply security policies without directly interfering with the data path.

API-based CASBs excel in environments where low latency is critical, as they avoid the performance overhead of intercepting traffic. They offer integration with cloud services, enabling features like historical data analysis and post-event forensic investigations. Despite potential limitations in controlling real-time threats, API-based CASBs are well-suited for organizations prioritizing performance and visibility into cloud use.

What Are the Challenges of Using a CASB? 

Scalability

Scalability is a major challenge in using CASBs, as organizations often grow their cloud service usage rapidly. A CASB must efficiently scale to handle increased data volume and user workloads without degrading performance. This requires infrastructure that can accommodate expanding network demands, ensuring consistent security coverage as cloud adoption increases.

Integration

Integration challenges arise when deploying CASB solutions alongside existing IT environments and security tools. Integrating CASBs with current systems is essential for maximizing their benefits and avoiding disruptions. This complexity involves ensuring compatibility with varying technologies such as enterprise identity management, SIEM systems, and existing cloud infrastructures.

Data Privacy

Data privacy concerns can complicate the deployment of CASBs, especially in jurisdictions with strict data protection regulations. Ensuring that CASBs comply with data privacy laws while protecting sensitive information in cloud environments requires precise policy configuration. This involves setting clear boundaries on data processing, retention, and sharing practices within cloud applications.

How to Implement a CASB Solution 

Select the Right CASB Solution

Selecting the right CASB solution involves evaluating products based on specific organizational requirements, such as security objectives, budget constraints, and integration capabilities. Key considerations include whether to implement an inline or API-based solution, the level of data protection needed, and compliance obligations. Organizations should conduct thorough market research and vendor evaluations to ensure the chosen CASB aligns with their cloud strategy.

Engaging with potential vendors is crucial to understanding different offerings and their compatibility with existing infrastructure. Demos and proof-of-concept trials can provide insights into each solution’s performance in real-world scenarios. Making an informed decision requires balancing functionality, cost, vendor support, and adaptability, ensuring the CASB effectively addresses unique business challenges.

Integrate the CASB with Cloud Services and User Directories

Integrating a CASB with existing cloud services and user directories involves configuring it to interact with enterprise infrastructure. This step includes syncing with identity management systems, such as Active Directory, and establishing secure connections with cloud service APIs. Proper integration ensures that the CASB can enforce policies based on user roles and access levels, maintaining security and data integrity.

Technical teams must focus on compatibility and interoperability with current tools to minimize disruptions. Collaboration with stakeholders and vendors is essential to address integration issues, maximizing the CASB’s potential. By ensuring smooth integration, organizations can enhance their security posture and leverage the CASB’s full capabilities across all user activities.

Configure Access, Data Sharing, DLP, and Security Policies

Configuring a CASB involves setting detailed policies for access control, data loss prevention (DLP), and security management to protect the organization’s cloud resources. Access policies define user permissions and authentication mechanisms, ensuring only authorized personnel can access sensitive information. DLP strategies prevent unauthorized data transfers, safeguarding intellectual property and critical assets.

Security policies should align with compliance requirements and organizational standards, defining acceptable use and incident response protocols. Regular policy reviews and updates in response to evolving threats and business changes are crucial. Tailoring configurations to organizational needs ensures robust security measures, minimizing risks.

Cloud security with Exabeam

The Exabeam Security Management Platform (SMP) offers a comprehensive solution for protecting your digital resources in the cloud and on-premises.

Exabeam Cloud Connectors allow you to reliably collect logs from over 40 cloud services into Exabeam Data Lake, Exabeam Advanced Analytics or any other SIEM. Updates are made automatically whenever there are API changes, so you don’t need coding skills or costly professional service engagements to ensure the right data is being collected.

Exabeam provides the connectivity necessary to monitor all your cloud services, including:

• Cloud services – such as Salesforce, Office 365, and Box. Exabeam monitors your cloud services at scale, providing unlimited logging for the ingestion and modeling cloud data. The pricing model is flat and user-based, ensuring visibility within your budget.
• Cloud infrastructure providers – such as AWS, Azure, and Google Cloud. Exabeam scans for anomalous activity throughout your cloud infrastructure through intelligent and automated detection.

The Exabeam SMP platform organizes the data in a user-friendly and visually appealing interface. The cloud security modules of the Exabeam platform take a data-driven approach that enables enhanced controls for visibility, monitoring, and security in the cloud:

• Smart collection of data logs – made possible by Exabeam Data Lake.
• Analysis-based threat detection – made possible by:
  • Exabeam User and Entity Behavior Analytics (UEBA) – for insight-driven threat detection enhanced by machine learning.
  • Exabeam Threat Hunter – for setting up automated threat detection and alerts.
  • Exabeam Threat Intelligence Service (TIS) – or real-time threat detection insights.
• Automated incident response – made possible by the Exabeam Incident Responder.