What is CASB (Cloud Access Security Broker)? Explained in detail

what is CASB

Nowadays, cloud services are well developed, and I think many people are using it not only for companies but also for individuals. Cloud services are very convenient because they can use various applications as long as they are connected to the Internet. However, existing security systems cannot address issues such as "shadow IT" and require new security measures.

The security solution/concept that is drawing attention is "CASB." This time, we will explain the outline and mechanism of CASB, the advantages, and the required background and differences from the next-generation firewall.

About CASB(Cloud access security broker)

CASB is a concept advocated by the American research firm Gartner in 2012. Based on that idea, solutions have been developed to take security measures when using cloud services.

CASB is deployed between users and cloud services to centrally manage and apply security policies regarding access to cloud resources. It is possible to centrally manage security measures required for using cloud services, such as authentication, access control, data encryption, and malware countermeasures.

Since cloud services can be used as long as they are connected to the Internet, there are various types of access in modern times. Understanding and managing all routes was a difficult part of conventional security systems, but CASB can solve such problems.

How CASB works?

The functions of CASB can be roughly divided into the following four. These functions enable security measures for using cloud services with CASB.

Visualization and analysis

By detecting and visualizing the cloud services used by your company, you can visualize and analyze the behavior of each user. For example, it is possible to visualize user behavior such as uploading and downloading to cloud storage such as Dropbox.

With this function, it is possible to manage detailed access privileges for each user. It is possible to set permission / non-permission for each cloud service, which helps prevent shadow IT.


You may have your own rules for each company. CASB has a function to respond according to corporate policy. For example, it is possible to send an alert when a file uploaded to Dropbox, etc. is open for viewing by anyone.

In addition, CASB checks the security capabilities of each cloud service and displays the risk level of the service. For compliance, it is possible to use the degree of risk of the cloud service used as a standard.

Data Security

Security settings for data operations such as uploading and downloading data, setting the disclosure range, and illegally operating the management screen are possible. For example, encryption is performed when data is transmitted, and data tampering is detected.

The most important thing to note when using cloud services is setting the disclosure range. This is because, as long as the data is uploaded on the Internet, anyone may be able to view it due to a setting error.

With CASB, you can centrally set the disclosure range, and perform access control based on encryption and data content.

Threat defense

It is a function to prevent threats hidden in cloud services. For example, you can restrict access to risky cloud services, detect malware, and restrict access to suspicious websites.

Various threats exist on the Internet. Some threats cannot be judged by the cloud service and cannot be prevented. Therefore, the function of threat defense is also necessary for self-defense.

Advantages of CASB

The introduction of CASB has two major benefits: These are essential benefits of using cloud services, so let's look at them one by one.

Reducing the burden on the system administrators

The first advantage is that it can reduce the burden on system administrators. There are many different types of cloud services, with daily updates and new services appearing. It is necessary to set and operate a security policy according to each service, but the system administrator's burden will be extremely heavy.

CASB investigates cloud services, determines security capabilities, and creates a risk level database. As a result, it is easy to formulate an appropriate security policy for each cloud service and take measures against new services, which reduces the burden on system administrators.

Prevent Shadow IT

Shadow IT refers to the loss of management by introducing IT services such as cloud services by a department different from the IT management department (such as the user department). If the cloud services used by users can no longer be managed, the potential risks in the enterprise will increase. Therefore, it must be centrally managed and security measures must be taken.

By using CASB, shadow IT can be prevented by the function of visualization and analysis. Since it is possible to detect the cloud service used by the user, if you are using a service that is not allowed inside the company, you can reduce the potential risk by blocking the communication.

A background that CASB is needed

In today's world where the use of cloud services is commonplace, it can be said that the introduction of CASB is indispensable. Because cloud services can be used not only by companies but also by individuals, CASBs are needed to firmly grasp the flow of data.

In the past, data communication within the company that should be protected was usually communication with on-premises servers. However, from the viewpoint of cost and scalability, the trend of migrating from on-premises to cloud services has become the mainstream. Since some parts cannot be handled by conventional security systems, CASB is needed as a new security system.

In addition, the introduction of cloud services is very easy and can be easily implemented by the user department. Therefore, CASB requires centralized management by the IT department to prevent the potential risks of shadow IT.

Difference between CASB and next-generation firewall

We've talked about CASB, but you may be wondering, "Can we do the same with a next-generation firewall?" The difference between CASB and the next-generation firewall is that "fine data security can be easily set for each cloud service and each user."

The next-generation firewall also has functions such as visualization and data security, but it is difficult to make detailed settings for each cloud service or user. In that respect, CASB allows you to make detailed settings for each cloud service and each user, allowing you to formulate more flexible security policies.

Furthermore, since CASB is more specialized for cloud services, there is also the difference that complicated settings for each service are not required.


CASB is a concept and solution that can be deployed between the cloud service and the user to perform the security measures required to use the cloud service. CASB consists of the following four functions.

  • Visualization, analysis
  • compliance
  • Data security
  • Threat defense

In today's world where cloud services have become more common, the introduction of CASB has the advantage of reducing the burden on system administrators and preventing shadow IT.

Also, some next-generation firewalls have the same functions as CASB, but CASB specialized for cloud services has the difference that you can easily set more detailed and flexible security policies. CASB is indispensable as a security measure for enterprises in the present age when the use of cloud services has become popular.

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