A Cloud Access Security Broker (CASB) is a security solution that sits between users and cloud service providers to monitor, control, and protect data moving to and from cloud applications.
CASBs provide visibility into cloud usage, enforce security policies, and help organisations maintain compliance when using Software as a Service (SaaS), Infrastructure as a Service (IaaS), and other cloud platforms.
As businesses increasingly adopt Microsoft 365, Azure, and other cloud services, CASB technology plays a critical role in managing cloud-related risk.
How a Cloud Access Security Broker Works
A CASB operates by integrating with cloud platforms through APIs or by acting as a secure gateway between users and cloud applications.
Its core functions typically include:
- Monitoring user activity across cloud services
- Identifying unauthorised or “shadow IT” applications
- Enforcing data protection policies
- Detecting suspicious or high-risk behaviour
- Applying encryption or tokenisation to sensitive data
By providing centralised visibility and control, a CASB enables organisations to manage cloud access without limiting productivity. It acts as an additional security layer beyond native cloud provider protections.
Why CASB Matters for London Businesses
London organisations frequently rely on cloud-based collaboration tools, remote working platforms, and SaaS applications. While these technologies improve agility, they also expand the potential attack surface.
A CASB helps organisations:
- Protect sensitive client and financial data in cloud environments
- Detect risky user behaviour or compromised accounts
- Prevent data exfiltration to unauthorised services
- Support GDPR compliance obligations
- Maintain control over hybrid working environments
In highly regulated sectors such as finance and legal services, maintaining visibility into cloud activity is essential for demonstrating operational resilience.
Key Capabilities of a CASB
Modern CASB solutions typically provide:
- Data Loss Prevention (DLP) integration
- User and entity behaviour analytics (UEBA)
- Threat protection for cloud applications
- Access control and policy enforcement
- Compliance reporting and audit support
These capabilities allow organisations to apply consistent security standards across multiple cloud platforms. Centralised governance reduces gaps that can arise when relying solely on individual application settings.
Risks of Operating Without a CASB
Organisations without cloud visibility and control may face:
- Unmonitored use of unauthorised SaaS applications
- Accidental sharing of sensitive information
- Increased exposure to account compromise
- Difficulty meeting regulatory audit requirements
- Limited detection of insider threats in cloud environments
As cloud adoption accelerates, unmanaged environments can quickly create hidden security risks.
Best Practices for Implementing CASB
To maximise effectiveness, organisations should:
- Integrate CASB with identity and access management controls
- Align cloud policies with data classification standards
- Monitor high-risk user activity continuously
- Enforce encryption for sensitive data in transit and at rest
- Conduct regular reviews of cloud application usage
A CASB should form part of a broader cloud security strategy rather than operating in isolation. When combined with endpoint protection, Multi-Factor Authentication, and managed monitoring, it significantly strengthens overall cyber resilience.
London Considerations
Financial Services: FCA-regulated firms require strong oversight of cloud usage and third-party services.
Legal Firms: CASB helps protect confidential client documents stored in collaboration platforms.
Healthcare Providers: Ensures secure handling of patient data within cloud-based systems.
SMEs in London: Cloud adoption is common, and managed CASB services provide enterprise-grade visibility without building complex in-house security infrastructure.
In London’s cloud-heavy and compliance-driven business environment, a Cloud Access Security Broker is an essential control for managing risk, protecting data, and maintaining regulatory alignment.
