What Is CASB, and How Is It Different From DLP?

Your company runs on cloud apps. Sales lives in Salesforce, files sit in Google Drive and OneDrive, conversations happen in Slack, and more of that work now flows through AI tools. A cloud access security broker, or CASB, is the control point that sits between your people and those cloud services, so security teams can see what's being used and set rules on it.

This guide covers what a CASB does, the functions it performs, and how it compares to data loss prevention (DLP), the term it gets confused with most.

A quick note on the name: this guide covers CASB in cloud security. If you're looking for the Colorado Association of School Boards, that's a different organization that happens to share the acronym.

What Is a CASB?

A cloud access security broker (CASB) is security software that sits between your users and the cloud services they use, giving your team visibility and control over that traffic. It enforces your security policies on cloud apps, spots unsanctioned tools, and protects the data moving in and out of them. The name describes the job: it brokers access to the cloud.

The idea took hold as companies moved off their own servers and into SaaS. Once data lives in apps that IT doesn't host, the old network perimeter stops being the place to enforce policy. A CASB gives that control point back, whether the app is company-approved or something an employee signed up for on their own.

The 4 Core Functions of a CASB

Analysts describe a CASB through four core functions: visibility into cloud usage, compliance with regulations, data security, and threat protection. Together they answer a plain question for security teams: which cloud apps are people using, and is sensitive data safe inside them? Most CASB products organize their features under these four.

How Does a CASB Work?

A CASB connects to your cloud services in three main ways: through APIs that scan data already sitting in an app, as a forward proxy that routes user traffic through the broker in real time, and as a reverse proxy for managed access. Many products combine these modes, so coverage reaches both data at rest and data in motion.

Each mode has trade-offs. API mode is quick to deploy and sees data across sanctioned apps, though it acts after the fact rather than in the moment. Proxy modes inspect activity live, but they need traffic routed through them, which gets harder as work moves into browsers and personal accounts the proxy never sees.

CASB vs DLP: What's the Difference?

The difference comes down to focus. A CASB secures the cloud apps your people use, controlling access and watching activity across those services. DLP protects the data itself, wherever it lives, by classifying sensitive information and stopping it from leaving. A CASB asks which app; DLP asks which data. They overlap, but they start from different places.

In practice the two blur together. Most CASB products include DLP features for the apps they cover, and most DLP products now reach into cloud storage. A CASB is app-first: it starts from the service and works inward to the data. DLP is data-first: it starts from the content and follows it across every channel.

Do You Still Need Both a CASB and DLP?

Often, yes. A CASB and DLP solve overlapping but different problems, so many security teams run both. Most CASB products include DLP for the apps they cover, and most DLP products now reach into cloud storage. The real question is where each gives you coverage the other can't.

These two work as layers. A CASB governs the cloud apps and catches shadow IT that never touches your network. DLP follows the data across endpoints, email, and storage, including places a CASB doesn't reach. Run one without the other and you'll have a blind spot on one side. That's why the market keeps bundling them, along with tools like a secure web gateway, into a single cloud security service.

Where Both Leave a Gap: Reading Intent at the Point of Action

Both a CASB and traditional DLP were built for a world of known apps and known files. They struggle with the fastest-growing exit path for data: an employee pasting sensitive text into a personal ChatGPT or Copilot session in the browser. That action looks routine, sits outside sanctioned apps, and carries intent that pattern matching can't read.

What these tools can't answer is whether a given action is normal for this person, this data, and this destination. A sales rep exporting a report from a sanctioned app looks fine. The same file landing in a personal AI account minutes later is a real exposure. Telling those two apart means reading the story behind the action, not the content alone.

This is the approach ORION Security takes. Instead of matching rules, it judges data in motion across three pillars at once: data lineage, which traces where a file came from and every step it's taken; LLM classification, which reads what the data actually is; and identity and environment, which knows whether the person, device, and destination are normal for that role. The output is a verdict on real data movement, not another alert to triage, so security teams see the exposures that matter without wading through false alarms.

That difference shows up in the field. One ORION Security customer caught the moment an employee moved company data into a personal AI account instead of the sanctioned one, a distinction the file alone never reveals. Most of these moves aren't attacks. Someone's taking the fast path to finish a task, which is why intent matters more than the content. To map where data actually travels across your cloud apps, browsers, and AI tools, grab a walkthrough.

Frequently Asked Questions

What does CASB stand for?

CASB stands for cloud access security broker. It's a security service that sits between your users and cloud apps, giving your team visibility into cloud usage and control over how data moves through those services. The term gets written as an acronym and pronounced "caz-bee."

Is Microsoft Defender a CASB?

Yes. Microsoft Defender for Cloud Apps is Microsoft's CASB offering. It gives visibility into cloud app usage, applies DLP and access policies, and flags risky activity across services like Microsoft 365 and third-party SaaS. Several other security vendors sell CASB tools too, often bundled into a broader cloud security platform.

Can a CASB stop data going into ChatGPT?

Only partly. If ChatGPT is accessed through a sanctioned, proxied path, a CASB can apply policy to it. But an employee signed into a personal ChatGPT account in the browser often sits outside that path, so the CASB can miss it. Catching that dependably takes tools that watch the browser and read the intent behind the paste.

How does a CASB fit with SASE and SSE?

A CASB is one piece of the broader cloud security stack. In many setups it's delivered as part of SSE (security service edge) or SASE (secure access service edge), alongside a secure web gateway and zero trust access. Buying it as a standalone tool still works, though vendors increasingly package these controls together so policy follows the user across apps and locations.