What Is a Cloud Access Security Broker (CASB)?


Cloud Access Security Brokers (CASBs) are security policy enforcement points based in the cloud. CASBs are situated between cloud application users of an organization and cloud service providers (CSPs). They work by combining many different policies to ensure cloud security across all of an organization’s applications and devices, working to prevent data leaks, malware, issues caused by shadow IT, and more.

As the use of cloud technologies continues to become the norm for many modern businesses, having traffic to a cloud flow through a CASB solution ensures better compliance to corporate policies including those that govern authentication, alerting, encryption, managing IoT devices, and access control.

Breaking Down the Four Pillars of a Cloud Access Security Broker (CASB)

The following four pillars define the foundational building blocks of a CASB solution. Together, the pillars ensure the CASB works properly to offer effective and flexible security solutions for the business.


Across both managed and unmanaged devices, one of the key concerns for an organization’s security team is one of visibility. CASBs allow organizations to use and take advantage of today’s developing cloud services while also governing access to data and activities within those services. For example, a cloud brokerage offers access to a sanctioned product suite but only to users on managed devices. The company is able to safely use the product without running the risk of unmanaged devices having the same access to data created and managed with that product.

Having a CASB solution also ensures that organizations get a real view of what their cloud spend looks like. CASBs can be used to discover all cloud services being used across all users – this means teams can more clearly define and analyze license costs, redundancies, and more, which is valuable financial information as much as it is a security measure.


Regulatory compliance has become the name of the game in today’s business landscape. While some businesses choose to outsource their systems and data storage to the cloud, they are still held responsible to the compliance regulations and controls surrounding the privacy and safety of enterprise data. Designed to ensure the safety of corporate and user data, compliance is now a major focus for organizational leaders, especially when it comes to data within the cloud.

CASBs can help security leaders with their compliance journey, ensuring the organization is on the right track to follow the right framework controls applicable to their business’s specific industry, region, or clientele including but not limited to PCI-DSS, GDPR, and HIPAA. Using a CASB also allows security leaders to determine the areas of highest risk in terms of compliance and provide a better direction, allowing security teams to focus their efforts and resources.

Data Security

In recent years, organizations of all sizes and industries have been making the move to cloud infrastructure, taking advantage of its ability to support remote workforces, scale to operations quickly, and enhance collaboration. As this trend continues, the question of how to secure the cloud takes the forefront, with the need to protect corporate cloud environments at the same level as data centers.

CASBs are a critical element of corporate cloud security in the modern tech landscape. Since it implements access management and data loss prevention (DLP) across all of an organization’s cloud-based assets, it empowers security teams to proactively secure the cloud and act quickly on suspected threats. Think of a CASB solution acting like a gatekeeper and mediator that can support the technical security needs of the organization as well as day-to-day business requirements and practices.

Threat Protection

Popular for the scalability and flexibility they provide, cloud environments are now holding more and more sensitive and business-critical data. Being able to detect and prevent unauthorized access to the cloud services and data is a major task undergone by today’s security teams.

While security teams are monitoring continuously for signs of malware, ransomware, and other cloud-based threats, they also need to ensure that their own employees aren’t introducing infected files or misconfigurations. CASBs can defend organizations from these pain points, making sure that organizations can identify at the first sign of compromise and maintain real-time response to potential issues. This is done by aggregating and monitoring typical usage patterns in the organization’s cloud infrastructure. CASBs can identify anomalous behavior that may be early indicators of an attack and be trained to recognize malicious activities.

How Do Cloud Access Security Brokers (CASBs) Work?

A CASB solution works by inspecting all of the traffic entering and leaving a cloud, able to block any traffic that either violates the organization’s corporate policies or poses potential security risks to the cloud infrastructure it is protecting. CASBs implement a combination of data protection, threat prevention, access control, and visibility for all cloud services used by the organization.

This is done through three main steps:

  • Discovery – CASB solutions use auto-discovery to compile lists of any third-party services and applications. The solution will also compile related users of these services and apps to understand the extent of cloud usage.
  • Classification – The solution then determines the level of risks associated with each service and app based on the kind of data within it and how it is managed and shared.
  • Remediation – After determining the risks, the solution sets business-specific policies that allow the organization to meet their predetermined security requirements. The CASB can be set up to notify and alert anytime one of these policies is violated.

The solution can either be integrated via API in order to establish the visibility and access control it needs to monitor the incoming and outgoing traffic to and from the cloud, or it can be configured to the traffic from other corporate cloud solutions that pass through the organization’s infrastructure.

How Businesses Use Cloud Access Security Brokers (CASBs)

With increased rates of cloud adoption in the modern workforce, CASBs are now considered a key element of enterprise security, supporting security leaders in managing corporate data, whether in motion or at rest, across all their cloud apps and platforms.

Here are the top three business reasons why modern organizations are moving towards employing cloud access security brokers in their long-term security strategies:

Cloud Usage Control

While CASBs are well known for being able to provide blanket visibility across an entire organization, they can also help security teams govern the organization’s cloud use at a more granular level, providing a finer control based on the service, identity, activity, data, and/or application in question. This means moving away from traditional ‘one-size-fits-all’ approaches that are too rigid and unscalable.

Cloud policies, through cloud brokerage, can be defined based on specific risks and service categories, allowing the organization to set corresponding actions for each policy. Actions like blocking, creating an alert, bypassing, encrypting, and quarantining are all examples of tailored actions that a CASB allows security teams to associate with each policy.

Data Security & Data Loss Prevention (DLP)

Only more and more data is created, captured, consumed as time goes by. According to the latest reports, global data reached 64.2 zettabytes in 2020 and is projected to reach all-time highs of 180 zettabytes by 2025. As the volume of data online continues to climb, CABS can help today’s organizations identify and remediate all the risks that come with handling business-critical data.

CASBs are instrumental in supporting DLP initiatives within an organization. Not only are they able to protect and prevent the loss of sensitive data across each cloud service used by an organization, CASB solutions can protect data in both sanctioned and unsanctioned cloud services, whether users are on-prem or remote, using a mobile device or accessing through a browser. CASBs support encryption, tokenization, and upload prevention – all key aspects of DLP strategies.

Threat Prevention & Risk Management

With the increase of cloud technologies and its use by today’s businesses, the cases of cloud-based threats and attacks on cloud environments also climb. CASB solutions are able to help organizations take a stand against malware and ransomware by detecting unusual behavior across cloud applications and services. CASBs are instrumental in helping security teams narrow down compromised users, rogue apps, and any high-risk configurations.

Since CASBs are designed to automatically detect and mitigate threats to the cloud infrastructure, security teams can significantly reduce the amount of risk on the organization’s cloud attack surface and limit the chance of a successful attack.

Shadow IT Management

This is the era of remote work and Bring-Your-Own-Device (BYOD) and security teams are working harder than ever to reign in visibility across the systems they are protecting. Delivering visibility into all cloud applications and services that an organization uses, CASBs can help security teams manage all sanctioned and unsanctioned instances. This includes the ability to discover their organization’s cloud app usage levels, reporting on how much spend is going towards the cloud, and continuously assessing risk to maintain appropriate and long-term access policies.

Teams can also train CASB solutions to build a comprehensive report of all cloud activity, allowing business leaders alike to make informed decisions on security measures, defensive strategies, and investments on supporting tech solutions and products.

Tips for Implementing Cloud Access Security Brokers (CASBs)

Implementing a CASB means having a clear grasp of what the business needs are and setting up the brokerage to best suit the organization’s specific systems. Security leaders can focus on the following steps to ensure a smooth implementation:

  1. Clearly assess your digital environment and outline a plan. Get a handle on what cloud services and apps already exist, what cloud-based risks are at play, and what the perimeters are for security and compliance needs specific to your business and industry.
  2. Choose the right CASB solution to fit the business. To ensure a good fit, companies can perform detailed proof of concepts (PoCs) or gather research from cybersecurity analysts.
  3. Determine the deployment location for the CASB. CASBs can be deployed on-prem or in the cloud. Proxy-based CASB deployment sits between the user and a SaaS (Software-as-a-Service) application. There are three deployment models to choose from:
    • API Control – This is ideal for gaining visibility into data and threats in the cloud. It supports faster deployment and offers comprehensive security coverage.
    • Reverse Proxy – This is ideal for devices that sit outside of thresholds of network security. In this mode, the proxy is closer to the user where the user’s devices or network routes traffic to the proxy.
    • Forward Proxy – This is ideal for working in conjunction with VPN clients or endpoint protection. In this mode, the proxy sits closer to the cloud service provider (CSP) where the cloud services route the traffic to the proxy.
  4. Integrate the CASB with the business’s cloud services, user directories, and security policies. Refer to any specific controls or requirements specific to your industry regarding sharing policies, encryption, and user access. User access can be secured through single-sign on (SSO) and authentication measures.
  5. Enable real-time monitoring and threat detection. As business needs evolve with time, it is crucial to regularly review and review cloud policies and work closely with the CASB to reflect any changes.


As cloud adoption continues to rise, traditional network security tools are far less effective, unable to provide the coverage needed to combat shadow IT. Cloud security access brokers work by giving security teams back granular and scalable control over corporate data, while preventing the risk that data loss and cloud-based threats bring.

Acting as the guardians of activity going in and out of all of an organization’s cloud environments, CASBs offer visibility, security policy enforcement, data protection, and threat detection. They allow businesses to confidently embrace new and innovative cloud technologies while ensuring control and adherence to stringent regulatory compliance controls.

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