What is a CASB?

Cloud access security brokers (CASBs) are security solutions placed between cloud service consumers and providers, enforcing security policies when users or entities want to access cloud-based resources. CASBs are a key element of enterprise security because they enable businesses to leverage cloud services while protecting sensitive data.

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What does a CASB do?

CASBs act as an intermediary between users and cloud service providers, addressing security gaps in an organization’s cloud usage. To enforce security policies and prevent data breaches, CASBs combine multiple methods of security policy enforcement such as authentication, authorization, encryption, single sign-on (SSO), credential mapping, device profiling, and alerting—as well as malware and ransomware detection and remediation. 

CASBs are flexible and versatile. They can be hosted in a cloud platform or on-premises datacenter, or even as a hardware device. They provide comprehensive coverage across software-as-a-service (SaaS), platform-as-a-service (PaaS), and infrastructure-as-a-service (IaaS) environments. Because of this multi-environment support, a CASB enables IT to expand an organization’s security policies from on-premises infrastructure to the cloud when migrating. 

Furthermore, a CASB functions as a centralized platform for security policy enforcement by consolidating multiple policies and implementing them across every resource the business uses in the cloud—regardless of where users are located or which devices they use to access your cloud environment.

A CASB enables businesses to manage bring your own device (BYOD) and hybrid workforces by implementing granular security controls.

Why do organizations need a CASB?

Cloud computing and SaaS application usage is growing, and many IT teams don’t have a clear grasp of all the apps in use on their networks. This type of “hidden app” is called shadow IT, and it presents a risk for organizations.

At every organization, there are four types of apps, each with different restrictions. First, there are business-critical applications that are generally approved to use within the company’s digital workspace. Then there are recreational and social applications some companies allow their employees to use while working, like Spotify. Most organizations also have restricted apps that are deemed inappropriate or not productive by the company. And then there are apps IT doesn’t know are being used. 

To keep corporate data secure, IT needs to know what apps are being used so they can put granular controls in place to minimize risk. A CASB addresses these challenges by providing visibility, data security, threat prevention, and compliance. It enables the organization to manage user access to all cloud resources. A CASB enhances compliance by integrating regulations into its security policies. 

How does a CASB work?

A CASB ensures an organization’s IT department has visibility and control of all cloud resources being used across the organization. Key security functions include: 

Data loss prevention

Data loss prevention, or DLP, detects and classifies a company’s most sensitive data across cloud providers, devices, and resources to prevent data loss. This function searches across all platforms for sensitive data, alerting on any potential data security risk.

Two-factor authentication and single sign-on

Two-factor authentication requires a two-step process to ensure proper user identification, such as sending a code to the user’s mobile device to verify the identity. Once authenticated, the user can access multiple applications using a single identifier.

File-level encryption

This function secures the data before it reaches the cloud, scrambling it so even if it is lost or stolen, it’s useless to an attacker. File-level encryption keeps the information secure at rest and in mobile devices.

Access control

Besides authentication and authorization capabilities, a CASB enables administrators to have complete control over application access. For instance, they can revoke user access to specific files, devices, or users when an employee leaves the company or a device is lost or stolen.


Top CASB solutions provide thorough reporting, including a comprehensive history of how the files and resources are accessed and used.


This function enables administrators to monitor activities in real time, analyze the user behavior baseline, and identify anomalous user activity.


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Types of cloud access security broker solutions 

There are two types of cloud access security broker solutions. 

In-line CASB solutions are placed in the path between the user and SaaS apps. In-line CASBs see all user traffic and can quickly identify which cloud applications people are using. This model is beneficial for organizations using forward proxy architecture and is an excellent way to identify shadow IT. In-line placement also enables real-time control over traffic flows, and it often provides native DLP for data in motion. 

Out-of-band CASB solutions are placed outside the path between the user and applications. This alignment provides more flexibility since it can be placed beside the SaaS through APIs or endpoints and obtain data from them. Out-of-band CASBs discover SaaS via app connectors or log data from endpoints or proxies. They can only learn about shadow IT if they receive logs from a device positioned between the user and the shadow IT component. This type of CASB often needs to share control commands with the API integrated apps, which can be cumbersome. However, out-of-band solutions often provide DLP functionality for data at rest as well as in motion. 

Benefits of CASB

There are many benefits to using a cloud access security broker, including:

  • Visibility and reporting: CASBs ensure the organization has visibility into all cloud programs, apps, and files that the business is using. The solution identifies the applications accessed by users in an organization, including unsanctioned and unknown applications, for all users within the organization, on mobile or desktop devices. 
  • Security controls: With a CASB, you can restrict access to provide granular control on app usage, social media, file uploads, and personal accounts. CASB capabilities include controlling specific functions in the app at the user level. For instance, you can allow app access only to corporate-approved domains, preventing users from using their personal Microsoft 365. 
  • Compliance: Businesses can outsource their systems and data storage to the cloud but keep responsibility for compliance with privacy and security regulations. Cloud access security brokers help monitor and maintain compliance requirements by integrating a range of regulations such as PCI DSS, GDPR, HIPAA, and more. A CASB identifies compliance risks and provides recommendations to the security team. 
  • Data security: Cloud migration enables teams to collaborate remotely, but it also increases cybersecurity challenges. A CASB with data loss prevention capabilities extends the reach of security policies from on-premises infrastructure to the cloud, enabling IT to see if sensitive content is traveling within or from the cloud. Additionally, cloud access security broker solutions allow the creation of new policies for cloud-specific content while addressing information overflow and the need to manage increasing amounts of data.
  • Threat protection: Employees or third-party actors can leak or steal sensitive data, whether by negligence or malicious intent. CASBs create a baseline of standard usage patterns, thus helping detect malicious behavior. Their security functions may include risk scoring, zero-day threat prevention, blocking access to risky regions, or full-scale malware protection.
  • Preserved bandwidth: CASB solutions prioritize the usage of business-critical apps over recreational (although sanctioned) applications. For example, you can restrict HD video streaming or specific video libraries, shopping websites, and the like. 

What can you use a CASB for?

Important and everyday use cases for a CASB include improving visibility, increased control, and enhanced compliance.

  • Improve visibility: Organizations want to be able to identify unsanctioned and unknown apps and the users accessing them. It’s critical to determine if these apps are safe or dangerous by identifying atypical access, such as unknown locations, sudden excess traffic flow, and more. CASB solutions can also help developers track their new app adoption and know how many users have begun to use the new application.
  • Increase control: It’s very common for organizations to restrict the usage of corporate applications like Microsoft 365 to corporate domains, thus not allowing personal email accounts within the organization’s network. A CASB enables granular control over social media apps. For example, a business can choose to allow access to company social media accounts while blocking browsing or shopping searches in Google, Yahoo, or Bing.
  • Enhance compliance: A wide range of companies now fall under the coverage of regulatory requirements, such as HIPAA or GDPR. Ensuring data privacy and security across distributed environments can be a hassle and a time-consuming job for IT professionals. CASBs make enforcing compliance simpler by integrating the regulation requirements into the security policies.

What to look for in a CASB solution

When looking for a CASB vendor, there are several functions organizations should look for.

The ability to identify shadow IT: The more information the CASB platform can have about shadow IT applications, the better. You should look for a solution that has a comprehensive app repository. Another essential feature you should consider is the ability to provide a built-in risk score analysis. You want the solution to tell you where the shadow apps are and if they are risky or safe. 

The deployment model: Keep in mind that the deployment type will significantly determine how the CASB can detect shadow IT. In-line solutions usually offer native functionality. Out-of-band CASBs integrate with other solutions, which can be third-party vendors for discovering shadow IT. Additionally, look for a solution that includes access controls that are executed in real time versus near real time. 

Built-in security functions: Look for a solution that integrates seamlessly with third-party security services or provides native advanced security functions. Key features include data loss prevention for data at rest and in motion, malware protection, and built-in user behavior analytics. 

Finally, don’t overlook the ability to support all workers across multiple devices and environments.