Skip to content Skip to navigation Skip to footer

What is a Cloud Access Security Broker (CASB)?

Key Principles and Strategies for Securing the Enterprise Cloud

Cloud Access Security Broker (CASB) Meaning

A cloud access security broker (CASB) is software or hardware that sits between users and their cloud service to enforce security policies as they access cloud-based resources. 

To further understand what is CASB, take note that it differs from the firewalls that organizations use to monitor and filter their network. CASBs can shed light into strange or unusual user activity and provide the company with cloud access control. Unlike firewalls, they provide deep visibility into cloud environments and offer granular control of cloud usage. 

CASBs are increasingly being used to protect against cloud security risks, comply with data privacy regulations, and enforce corporate security policies. They are increasingly important to organizations as employees use personal, unmanaged devices to access corporate networks from new, disparate locations, which creates even more cloud security risks.

The concept of CASB first emerged as the rise of cloud computing created the need for more consistent security across multiple cloud environments. Using CASBs, organizations were able to gain deeper visibility into what was happening in their cloud and Software-as-a-Service (SaaS) deployments and protect all user and sensitive corporate data in these environments.

The threat landscape rapidly evolves, and with blended threats, multiple exploits, and obfuscation technologies that make detection more difficult, organizations need solutions that make protecting their data and users easier. CASBs are increasingly important to providing protection against malware and phishing attacks, securing access to cloud services, and ensuring cloud application security. 

Four Pillars of CASBs

CASB solutions are split into four pillars or functions that keep organizations' cloud services secure:


Organizations must have visibility into user activity across their cloud applications, including on sanctioned and unsanctioned applications, known as shadow IT. A particular risk of cloud usage is activity that takes place beyond IT’s line of sight because the organization’s data is no longer covered by its compliance, governance, and risk policies. So CASBs are crucial to identifying this high-risk behavior that IT teams may not be able to see.

A CASB solution provides the comprehensive visibility of cloud application usage, such as device and location information, to help organizations safeguard data, intellectual property, and users. It also provides cloud discovery analysis, which enables organizations to assess the risk of cloud services and decide whether to grant users access to applications. This allows the organization to establish more granular control over their cloud environments by providing different levels of access based on a user’s device, location, and role within the business.


Organizations now have a wide range of cloud supplier options and likely use several different vendors for various solutions. However, organizations remain responsible for ensuring regulatory compliance around the privacy and safety of their data, regardless of whether they outsource services or manage it themselves. 

CASBs help organizations ensure compliance with the increasingly stringent, constantly evolving requirements of data and privacy regulations like the California Consumer Privacy Act (CCPA), the European Union’s General Data Protection Regulation (GDPR), and the Health Insurance Portability and Accountability Act (HIPAA). CASBs also play an important role in meeting the security requirements of ISO 27001 and the Payment Card Industry Data Security Standard (PCI DSS). 

Using a CASB solution allows organizations to pinpoint the compliance risks they face and understand what they need to do to address those risks.

Data Security

Organizations must ensure they protect their sensitive data even as cloud usage continues to increase and while implementing data loss prevention (DLP) tools. On-premises DLP solutions are effective in protecting data but cannot extend that protection to cloud services. 

Organizations therefore must combine a CASB application with their DLP tool to gain visibility of sensitive data moving between and across their on-premises and cloud environments. This enables organizations to monitor user access to confidential information, regardless of where it is on their network. Through a combination of features and technologies like access control, collaboration control, DLP, encryption, information rights management, and tokenization, organizations can minimize the loss of corporate information.

Threat Protection(威胁检测)

Organizations face an ever-increasing threat from outside hackers through stolen credentials and insider attacks. As such, companies must be able to detect and prevent suspicious behavior, including that of authorized users.

CASBs enable organizations to specifically protect against insider attacks from authorized users by creating a comprehensive regular usage pattern that can be used as a comparison point. Using machine-learning techniques, CASBs can then detect unusual activity as soon as a user gains improper access or attempts to steal data. They also use technologies and techniques like adaptive access control, dynamic and static malware analysis, and threat intelligence to block and prevent malware attacks. 

Four Pillars of CASBs

How CASBs Improve Cloud Security

What does a CASB do to improve cloud security? It ensures that traffic between user devices and cloud providers complies with organizations’ security policies. They provide insight into cloud application usage across cloud platforms, which is crucial in highly regulated industries with large, disparate workforces accessing multiple on-premises and cloud environments.

A CASB employs an auto-discovery process to identify the cloud applications being used, then pinpoints the applications, users, and other factors that pose a risk to the organization. The CASB cloud tool can then impose various access controls, compliance reporting tools, and other technologies to protect data and users. These include encrypting data the moment it is created until it sits at rest in the cloud, single sign-on (SSO) to provide one-time access across multiple applications, and user behavior analytics that identifies suspicious activity or signs of a potential cyberattack or data breach.

CASBs allow organizations to control and visualize the threats their cloud environments face. They use a three-step process to ensure organizations meet their enterprise security requirements:

  1. Step 1—Discovery: A CASB solution uses an auto-discovery feature to list all the third-party cloud services being deployed by an organization, as well as all the employees using those services.
  2. Step 2—Classification: The CASB will determine the level of risk of each cloud application the organization has deployed. It does this by assessing what the cloud application is, the sort of data it contains, and how data is being shared by users.
  3. Step 3—Remediation: After assessing the risk of each application, CASB tools will use that information to create a policy that meets the organization’s security requirements. This will include data and user access policies, and the CASB will automatically take action if an event occurs that violates those policies.

CASBs also provide additional functionalities and protection, such as authentication to verify user identities and ensure only the right people get the right level of access to corporate resources, DLP to prevent users from leaking sensitive information outside the organization, and firewalls or web application firewalls (WAFs) to scan for, identify, and prevent malware.

They are also particularly useful to organizations that have shadow IT operations or allow users to procure and manage their own cloud environments. That is because CASBs can collect data that is useful not just for security but also for monitoring the usage of cloud services for budgeting purposes.

Key Reasons Why Organizations Need CASB Security

  1. To govern cloud applications: CASBs provide a centralized view of an organization’s cloud environment, which helps them understand which users are accessing which applications, where they access them from, and the device they use to do so. CASBs also rate cloud services’ risk level and trustworthiness, as well as automate access controls and data permissions, which is crucial to governing cloud applications.
  2. To defend against cloud-based threats: CASBs monitor suspicious activity, such as excessive logins, and use anti-malware and sandboxing technology to analyze and block potential threats in the cloud. As the sophistication and volume of cloud-based attacks increase, it is vital for organizations to understand the behavior and characteristics of the cloud threats they face and quickly respond to them.
  3. To secure sensitive data: CASB solutions enable organizations to detect and remove the sharing of sensitive data outside their networks. They can also set policies that ensure only authorized users are allowed to access certain types of data.
  4. To ensure cloud compliance: CASBs are a crucial tool in helping organizations meet increasingly stringent data and privacy regulations. They provide automated remediation, reporting capabilities, and policy creation and enforcement required to comply with industry and government-led mandates, rules, and standards. 
2021 Cybersecurity Cloud Security Report

2021 Cloud Security Report

Cybersecurity Insiders 2021 Report provides insights into the state of public cloud security, biggest security threats and the benefits of cloud adoption

Get Report Now

How To Choose a CASB Solution

Choosing a CASB solution is reliant on finding the right service that meets the organization’s individual requirements. Organizations must set out their needs and the goals that a CASB will help them to achieve. They then must research their options by compiling insights from cybersecurity analysts, carrying out reference calls with providers, and perform a detailed proof of concept.

An important consideration is whether the CASB will grow with the organization and be able to protect it as its threat landscape increases. The right CASB provider will update and evolve the organization’s cloud compliance and security policies. 

A CASB should also be capable of protecting all of an organization’s environments. For example, the provider must be able to secure SaaS programs but also safeguard Infrastructure-as-a-Service (IaaS) environments through activity monitoring, DLP, and threat protection.

A CASB solution differs from a firewall, but it can complement tools like next-generation firewalls (NGFWs), which filter traffic to protect organizations from threats. NGFWs offer protection from external and internal threats through features like packet filtering and network monitoring that ensure deeper inspection capabilities and help identify attacks. When paired with a CASB, this protection ensures next-level, enhanced visibility of an organization's various networks and cloud environments.

How Fortinet Can Help

The Fortinet FortiCASB solution is a cloud-native subscription service that delivers the four pillars of CASB security to organizations’ SaaS applications. It offers the visibility, compliance, data security, and threat protection required to prevent cloud-based threats and ensure cloud compliance.

FortiCASB supports major SaaS application and service providers and provides advanced insights into organizations’ secure cloud access. The tool gives organizations visibility into what is happening across their cloud environments, including user and data activity, and provides comprehensive reporting tools.

The FortiCASB solution uses customizable DLP tools to ensure compliance. It offers configuration, entitlement, and usage assessments to enhance the control and visibility of cloud applications and uses advanced analytics to quickly identify threats and violations of corporate policies. FortiCASB also integrates with antivirus and sandbox tools to store data and protect against the latest emerging threats, while providing consolidated reporting for FortiAnalyzer and FortiGate that detects the on-network usage of SaaS applications.


What does CASB mean in cybersecurity?

CASBs are increasingly important to providing protection against malware and phishing attacks, securing access to cloud services, and ensuring cloud application security. 

What does a CASB do?

A cloud access security broker (CASB) is software or hardware that sits between users and their cloud service to enforce security policies as they access cloud-based resources. 

What does a CASB do to improve cloud security?

It ensures that traffic between user devices and cloud providers complies with organizations’ security policies. They provide insight into cloud application usage across cloud platforms.