Security Encyclopedia

Cloud Access Security Brokers (CASB)

A Cloud Access Security Broker (CASB) is a product that enables enterprises to forwardly deploy security features of their on-premise infrastructure to applications they have in the cloud.

CASBs take the form of software that sits between users and a cloud-hosted application. They have four main ingredients: visibility over user activity, compliance with data loss prevention (DLP) policies, technical enforcement of security (e.g. access control, encryption), and protection from malicious activity by users or intruders.

Through the use of APIs, forward proxy for managed devices and reverse proxy for unmanaged devices, CASBs perform a number of security services in the realm of enforcement, compliance, and governance:

  • Access blocking as needed
  • Access monitoring
  • Authentication
  • Authorization
  • Application controls
  • Data access controls
  • Device profiling
  • Encryption
  • Logging
  • Malware prevention and detection
  • Policy enforcement
  • Single sign-on (SSO)
  • Tokenization


"We're looking at a CASB for the standard benefits of DLP and threat detection, since our cloud-hosted app handles a a tremendous amount of customer activity and data. We're relieved to learn that some CASBs have GDPR compliance built into the controls."