What is a CASB (cloud access security broker)?

A cloud access security broker (CASB) is a security intermediary between cloud users and cloud-based applications. CASBs manage and enforce all data security policies and practices, including authentication, authorization, alerts, and encryption. They provide visibility into cloud application usage, monitor user behavior, and help ensure compliance with security policies, protecting sensitive data and managing risks associated with cloud services across devices and endpoints.

CASBs protect organizations through a combination of prevention, monitoring, and mitigation techniques. In addition to reviewing user activity, CASBs can warn administrators about likely malicious activity, block the installation of malware or other threats, and detect potential compliance violations. They may also review an organization’s firewall or proxy logs to better understand cloud application usage and identify anomalous behavior.

A CASB is especially helpful given the proliferation of cloud-based services and the growing popularity of bring-your-own-device policies. Taken together, these two trends have greatly expanded the data environment, making it harder for the IT organization to oversee network use and ensure the protection of enterprise data.

Because CASBs access personal devices, it is important for them to observe modern privacy standards and inspect only corporate data.

CASB vs. CSPM vs. CWPP

The core elements of cloud security posture management (CSPM) are often compared to those of cloud workload protection platforms (CWPPs). CSPM focuses on securing cloud APIs, preventing misconfigurations, and integrating into the continuous integration/continuous delivery (CI/CD) pipeline. CWPPs, on the other hand, focus on runtime protection and continuous vulnerability management for the cloud container. But CSPM and CWPPs are both designed to protect sensitive information stored in the cloud.

While CSPM and CWPPs work to secure data, a CASB works to improve visibility across endpoints. This includes visibility into who is accessing data and how it is being used.

CASBs, CSPM, and CWPPs all work together to secure data in — and access to — the cloud. Organizations are encouraged to deploy all three security methods to optimize their cloud security infrastructure.

Comparing traditional and next-generation CASB models

Comparing different CASB models highlights the strengths and limitations of traditional and next-generation approaches. Traditional CASBs typically focus on securing cloud services by providing visibility, data protection, and compliance enforcement through methods like API-based and proxy-based deployments. These models are effective for basic cloud security needs, offering control over data flows and user activity within cloud applications. However, they often face challenges in adapting to the dynamic and complex nature of modern cloud environments, particularly in terms of real-time threat detection and response. Traditional CASBs might struggle with handling encrypted traffic, sophisticated cyber threats, and the scalability required by rapidly evolving cloud infrastructures.

Next-generation CASBs, on the other hand, are designed to address these limitations by incorporating advanced capabilities like machine learning, behavior analytics, and deep integration with other security tools. These models offer enhanced threat detection, more granular policy enforcement, and the ability to protect a broader range of cloud applications, including those that are less traditional or more complex. Next-gen CASBs are also better equipped to handle the demands of multi-cloud and hybrid cloud environments, providing more scalable and adaptable security solutions. By leveraging these advanced features, organizations can achieve more robust and comprehensive protection across their cloud services, ensuring that their security posture keeps pace with the rapidly changing cloud landscape.

Key features and functions of a CASB

The primary purposes of the CASB are to protect the organization’s sensitive data from theft, loss, or leakage and to provide visibility and control over an organization's use of cloud services. They fill a security void created by the shift to the cloud and an explosion of endpoints. Core functions of a CASB include:

Data governance

A CASB is responsible for governing the organization’s cloud usage with granular visibility and a wide variety of controls based on user identity, service, application, activity, location, or endpoint. The CASB also automates the management of data policy violations through a variety of actions, such as blocking, overriding, alerting, encrypting, or quarantining. CASBs also provide the IT team with a summary of actions taken in response to policy violations.

Data security

CASBs work to prevent the theft, loss, or leakage of data across all cloud services and applications through encryption, tokenization, and other techniques. They establish data loss prevention (DLP) tools and processes for data in use, in motion, or at rest from any cloud service or application to any endpoint. They also proactively monitor the cloud security environment for policy violations. 

Threat protection

CASBs establish full visibility into — and control over — organizational data across all cloud services. They identify and isolate cloud-based threats, including malware and ransomware. CASBs also leverage AI, machine learning (ML), and other intelligent automation tools to detect anomalous behavior. They continuously evolve to respond to the ever-changing threat landscape and ensure ongoing threat protection. Additionally, CASBs alert the cloud security team to any active threats or anomalous activity.

Understanding CASB deployment models: API-based, proxy-based, and hybrid approaches

The different CASB deployment models are designed to provide organizations with flexible and effective ways to secure their cloud environments. These models typically fall into three categories: API-based, proxy-based, and hybrid approaches. The API-based model integrates seamlessly with cloud service providers (CSPs) by using their APIs, enabling the CASB to monitor and enforce security policies without impacting user experience. This model is particularly well-suited for managing popular cloud services like Microsoft 365 and Google Workspace, as it allows for visibility and control over data flows within the application layer. However, it may have some limitations in providing real-time threat detection and mitigation.

In contrast, proxy-based deployment offers in-line security by routing cloud traffic through the CASB, allowing for real-time inspection and enforcement of security policies. This can be implemented as a forward proxy, where user requests are directed through the CASB, or as a reverse proxy, where the CASB intercepts traffic to and from the cloud application. While this approach provides robust protection and granular control, it may introduce some latency and require more complex configuration. Hybrid deployment models combine the strengths of both API-based and proxy-based approaches, delivering comprehensive security coverage that balances the seamless integration of API-based models with the real-time protection offered by proxy-based solutions.

What are the four pillars of CASB?

CASBs are based on four main principles: visibility, compliance, cloud security, and threat protection.

1. Visibility

The shift to the cloud has made it exponentially more difficult for IT organizations to maintain visibility into where and how their data is being used. If an organization cannot “see” this data, then it cannot ensure that its use complies with the organization’s data policies.

A CASB helps improve the organization’s visibility into which cloud services, apps, and endpoints are accessing enterprise data. It also controls varying levels of access based on user identity, location, job function, or device. For example, a CASB may allow select files to be shared internally with authorized users and block the sharing of the same files with external parties.

2. Compliance

Despite the increasing complexity of a cloud-based business model, organizations must continue to comply with a wide variety of government and industry regulations concerning privacy and responsible use of enterprise data. A properly designed and configured CASB helps simplify the regulatory environment by automating reporting activity and detecting possible violations with relevant regulations, such as the GDPR, HIPAA, and PCI DSS.

3. Cloud Security

As companies move to a more remote and dispersed workforce and rely more heavily on cloud-based infrastructure, protecting sensitive data has become more challenging. In addition, the growing sophistication of hackers and digital adversaries highlights the importance of prevention capabilities. While traditional data protection solutions are designed to safeguard data being used on-premises, they must be adapted and expanded to protect cloud services.

A CASB supplements the organization’s existing DLP, allowing IT to apply the same principles to data in use, in motion, and at rest within a cloud environment.

4. Threat Protection

The growing sophistication of digital adversaries increases the risk of data theft or leakage. Meanwhile, the relatively complex nature of cloud architecture increases the possibility of human error. For example, misconfigured Amazon S3 buckets that leave ports open to the public or insecure accounts or APIs can turn typical cloud workloads into obvious targets that a threat actor can easily discover with a simple web crawler.

CASBs help organizations improve data visibility within the cloud environment through a variety of detection, monitoring, and prevention tools. For example, they can enable the InfoSec team to scan and remediate threats across internal and external networks in real time. CASBs also allow organizations to detect and block unauthorized user access to cloud services and data.

Why do you need a CASB?

The benefit of cloud computing is also its drawback: Users can access cloud environments from anywhere with an internet connection, but so can cybercriminals and digital adversaries.

For businesses shifting to a cloud-based model, security is a top concern. Organizations must design and implement a comprehensive cloud security solution to protect against an expanding array of threats and increasingly sophisticated attacks within the cloud environment. Traditional security strategies intended to protect on-premises hosted networks and associated assets must be updated to address threats related to the cloud environment.

It is important to remember that cloud networks adhere to what is known as the shared responsibility model. This means that much of the underlying infrastructure is secured by the CSP. However, everything from the operating system to applications and data is the responsibility of the user. Unfortunately, this point can be misunderstood, leading to the assumption that cloud workloads are fully protected by the CSP. This results in users unknowingly running workloads in a public cloud that are not fully protected, which means adversaries can target the operating system and applications to obtain access. Even securely configured workloads can become a target at runtime, as they are vulnerable to zero-day exploits.

Benefits of a CASB

CASBs give organizations much deeper visibility into how data is being used within the cloud environment, including cloud applications, cloud services, and cloud users. They are designed to help organizations protect against the security challenges and weaknesses present in the cloud.

For example, a properly configured CASB can reduce the risk of shadow IT, or applications and infrastructure that are managed and utilized without the knowledge of the enterprise’s IT department. Shadow IT is a growing concern for many organizations, given the shift to an agile DevOps software model. In this model, developers often spawn workloads using their personal accounts. These unauthorized assets are a threat to the environment, as they are often not properly secured — for example, they may be accessible via default passwords and configurations. CASBs provide organizations with visibility into instances like this and can offer automated recommendations for how the IT team can respond to these issues.

How to choose a CASB

For organizations looking to adopt a CASB, it is important to consider this solution as a single tool within a broader cybersecurity strategy. Organizations should evaluate the CASB vendor’s ability to integrate with their existing security infrastructure, such as their DLP tool, security information and event management (SIEM) solution, firewall, and secure web gateways. Additional considerations include:

Examine the solution in relation to specific use cases. Every organization’s cloud security needs are unique. When considering a CASB vendor, organizations should establish which use cases they wish to prioritize and evaluate vendors accordingly. This will help ensure that the organization selects a vendor with expertise that matches its specific needs.

Evaluate the CASB vendor landscape. Leverage media coverage and analyst reports to determine the organizations that have a strong track record in preventing breaches as well as quickly and effectively remediating security events. As noted above, it is important to identify vendors that can deliver the organization’s specific use cases. If the business is considering multiple use cases, be sure to consider any potential limitations within the solution.

Conduct a trial. Many vendors offer clients the ability to pilot a critical app prior to a full deployment. This step helps ensure that the CASB solution is compatible with the organization’s current cloud infrastructure and can be supported by the company’s existing resources.

Outline CASB functionalities. During the trial and evaluation period, the organization should also determine the CASB’s role in authentication, authorization, alerts, and encryption. For example, the IT team will need to determine when and how to apply granular, risk-based authentication — and if the CASB will deliver this functionality. The team may also need to determine if the CASB solution will integrate with existing identity as a service (IDaaS) or single sign-on (SSO) tools.

Conduct regular audits. The threat landscape can change quickly. It is important to conduct regular audits with your CASB vendor once engaged to ensure your organization and data are adequately protected.

Getting started with CrowdStrike Falcon Cloud Security

CrowdStrike offers comprehensive cloud security solutions designed to protect data, applications, and workloads across all types of cloud environments. Whether you're using public, private, or hybrid clouds, CrowdStrike Falcon® Cloud Security helps organizations achieve end-to-end security through a unified platform​.

By leveraging CrowdStrike’s powerful cloud security tools, organizations can secure their cloud environments while benefiting from real-time threat intelligence and a proactive approach to incident response.

To experience CrowdStrike’s capabilities firsthand, organizations can request a Cloud Security Health Check, which detects misconfigurations, vulnerabilities, and threats and offers guided remediation for cloud infrastructure and apps.