What is a CASB?

A CASB (cloud access security broker) is a cloud security tool that enforces security policies between users in an organization and cloud services. CASBs are one of five major security functions in the increasingly popular SASE (Secure Access Service Edge) security model, alongside software-defined wide area network (SD-WAN), firewall-as-a-service (FWaaS), secure web gateway (SWG), zero-trust network access (ZTNA).

How Do CASBs Work?

CASB’s functions are categorized by Gartner into four pillars:


1. Visibility

2. Compliance

3. Data Security

4. Threat Protection

CASB Types

CASBs are categorized by their method of deployment.

There are three main types of CASB:

1. API-based CASB

2. Agent-based CASB (Reverse proxy)

3. Agentless CASB (Forward proxy)

Key takeaways

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    CASBs consolidate security policies across all cloud services an organization uses.
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    They are fundamental to SASE, an emerging Gartner concept that converges network and security functions into a cloud-based model.
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    CASBs can be deployed through APIs or proxies.
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