What is a CASB (Cloud Access Security Broker)?
A Cloud Access Security Broker (CASB) is a security enforcement point positioned between cloud service users and cloud service providers to help organizations monitor and manage their use of cloud-based services. CASBs enforce security policies and provide visibility into cloud applications, enabling companies to safely adopt cloud services while maintaining control over their data. CASBs can be deployed either on-premises or delivered through the cloud, using a combination of forward and reverse proxy methods, APIs, and polling for periodic status updates.
How CASBs Work
CASBs act as intermediaries between users and cloud services, ensuring that only authorized users can access sensitive data and applications. They monitor traffic between the organization and cloud applications, applying security policies to prevent unauthorized access, data breaches, and other potential threats. CASBs provide organizations with the ability to enforce corporate security measures of cloud applications.
Key Capabilities of CASBs
1. Visibility: CASBs offer visibility into the use of known cloud services and SaaS applications, allowing organizations to track what apps are being used, who is using them, and how data is being accessed and shared.
2. Compliance: With increasing regulatory requirements, CASBs help organizations ensure that their use of known cloud services aligns with compliance standards, such as GDPR, HIPAA, and PCI DSS.
3. Threat Protection: CASBs can provide threat detection and mitigation capabilities, identifying suspicious or anomalous behavior that could indicate a cyberattack. This includes monitoring for malware, compromised accounts, and insider threats.
4. Data Loss Prevention (DLP): CASBs enable data loss prevention by monitoring and controlling the flow of sensitive data to and from managed cloud services. They help prevent accidental or malicious data leakage by enforcing policies that restrict the sharing or downloading of sensitive information from cloud applications and services.
What are the Limitations of a CASB?
Visibility
CASBs discover logs and events, not user-SaaS relationships. In addtion, CASBs rely on logs and events generated when users pass through their infrastructure, which was designed for how SaaS was consumed in the past. This approach works for detecting traditional SaaS applications, but it struggles to account for the modern SaaS landscape, where business-led IT is prevalent. As a result, CASBs often fail to discover a large portion of the SaaS applications in use today, including shadow IT. The SaaS attack surface has evolved to include over 1,100 apps in the average enterprise, many of which are outside of IT’s control. CASBs were built for an era when SaaS was primarily limited to a few major platforms like Salesforce and Office 365, leaving them blind to most of the modern SaaS attack surface.
Prioritization
CASBs can only prioritize the SaaS applications they can see, ignoring those that fall outside their infrastructure. This limited visibility leads CASBs to focus on blocking or restricting the few SaaS apps they detect, while overlooking the vast majority of business-led SaaS. As remote work expands, many employees access SaaS applications directly, bypassing CASB controls entirely. With over 60% of the SaaS attack surface existing outside of IT's oversight, CASBs are unable to properly prioritize real SaaS risks, rendering their efforts largely ineffective in addressing modern SaaS security challenges.
Security
CASBs focus on securing pathways—such as managed devices and sanctioned SaaS apps—rather than adapting to the way people access modern cloud services. In theory, CASBs assume ideal conditions where all users access SaaS applications through controlled network infrastructure and devices, but the reality is far more complex. The shift to remote work and the growing use of unsanctioned SaaS apps have exposed significant gaps in CASB security. For CASBs to be effective, several conditions must align: all SaaS apps need to be approved, all devices must be managed, and all traffic must pass through secure gateways. These assumptions rarely hold true in today’s dynamic, user-driven SaaS environment, leaving dramatic security gaps in most CASB deployments.
Managing the SaaS Lifecycle
CASBs struggle to manage the complete SaaS lifecycle, from onboarding to decommissioning. While they may provide some visibility into current SaaS usage on managed devices, they fail to account for past SaaS applications and users. This leaves a trail of unmanaged accounts, zombie access, and duplicate credentials—entirely outside CASB's reach. When it comes to offboarding, CASBs also fall short. They can only manage SaaS apps within their limited scope—typically around 40% of an organization's SaaS ecosystem. The remaining 60% of apps, often used outside of CASB control, require manual offboarding processes. This fragmented approach to lifecycle management adds complexity and inefficiency, leaving significant gaps in securing the full SaaS lifecycle.
Complex Configuration
CASBs can be complex to implement and configure, especially for large organizations with multiple cloud environments, not to mention the high cost of ownership and operation.
Performance Impact
Because CASBs rely on proxies, it delays the network's performance, which can negatively impact application performance and user experience.
An Alternative to CASB
A more effective approach to SaaS security is leveraging a SaaS Security Control Plane (SSCP), designed specifically for modern security environments. Unlike CASBs, an SSCP is built to address the complexities of today’s SaaS landscape by identifying risks and threats across the entire SaaS ecosystem, including both IT-managed and business-led SaaS.
The SSCP orchestrates security throughout the entire SaaS lifecycle—enabling security teams to discover SaaS applications, evaluate and prioritize risks, and implement security controls across multiple systems and environments. This comprehensive approach ensures that all SaaS apps, whether sanctioned or not, are continuously monitored and secured, making SSCPs a critical element in modern security architectures.
Additionally, Grip's SSCP uses identity as the central control point, requires no proxies or agents, and deploys in just 10 minutes, delivering immediate ROI. Want to learn more? Book a demo now.
Related Blog Posts
Comparing the Top 10 Leading CASBs
Alternatives to CASB for SaaS Security
4 Reasons Why CASB Fails
