Agentless vs Agent-Based Cloud Scanning: How to Actually Choose

Shop for almost any cloud security or cost tool and you’ll hit the same fork in the road: agentless or agent-based. Vendors tend to present whichever one they sell as the obviously correct answer. It isn’t. They see different things, and the right call depends on the question you’re trying to answer.

This is the practical version: what each approach can and can’t see, what it costs you in effort, and a rule of thumb for choosing.

The one-line difference

An agent is a small program you install inside a workload, on a VM, a container image, a host, that runs there and reports back. Agentless means no install: the tool reads your cloud through the provider’s own APIs using a role or key you grant it.

So the distinction isn’t really “with software” vs “without software.” It’s where the tool stands. An agent stands inside the workload and looks around. An agentless tool stands outside, at the control plane, and reads how everything is wired up.

That vantage point decides everything else.

What agentless actually sees

From the outside, through the API, you can read the entire shape of an account without touching a single workload:

• Which storage buckets are public, and which have encryption off.
• Which security groups or firewall rules allow 0.0.0.0/0 on a database port.
• Which IAM roles carry wildcard permissions or haven’t been used in a year.
• Which volumes are unattached, which instances are idle, which snapshots are orphaned.
• Whether logging, threat detection, and audit trails are switched on.

Notice that the cost waste and the security risk live in the same place, the configuration, which is why a single agentless pass can surface both at once.

The two big advantages are reach and friction. Reach, because one granted role can read thousands of resources across every region in minutes, including the forgotten dev account nobody remembers. Friction, because there’s nothing to roll out: no fleet-wide install, no version drift, no agent eating CPU on a production box.

What agent-based actually sees

Now stand inside the workload. The control-plane API has no idea what’s happening within a running container, an agent does:

• The exact packages and library versions installed, and which carry known CVEs.
• Processes that are actually running, and whether one just spawned a shell it shouldn’t have.
• File integrity changes, suspicious network connections, in-memory behavior.
• Drift between the image you built and what’s actually executing right now.

This is depth the API can’t give you. No amount of reading the cloud’s metadata tells you that a process inside a pod is beaconing to a strange IP. For runtime detection and vulnerability management at the workload level, agents are the tool.

The cost is exactly the friction agentless avoids. Someone has to deploy the agent everywhere, keep it updated, and accept that it runs with privilege inside your workloads, an agent is itself attack surface and itself a thing that can break a box.

A side-by-side, honestly

The honest limitation of going agentless

Here’s the part vendors skip when they’re selling agentless: it is blind to runtime. If an attacker is already inside a container, doing something malicious in memory, an agentless scanner reading the API won’t catch the act itself. What it will catch is the misconfiguration that let them in, the public endpoint, the over-broad role, the database open to the world, which is where the overwhelming majority of cloud incidents start.

That’s the useful way to frame it: agentless closes the front door; agents watch the rooms. Most breaches are someone walking through an unlocked front door, so posture is where the leverage is. But if your threat model includes sophisticated in-workload activity, agentless alone isn’t enough, and any tool that tells you otherwise is overselling.

A rule of thumb

• Start agentless. It’s the fastest way to know whether anything is dangerously exposed across your whole estate, and it carries almost no operational cost. For most teams, most of the risk is here.
• Add agents where the stakes justify the rollout, your most sensitive workloads, the ones where in-runtime detection genuinely matters and you’re willing to own the deployment.
• Don’t pay agent-level operational cost to answer agentless-level questions. “Is anything misconfigured?” doesn’t need software on every box.

Match the tool to the question, not to whichever camp a vendor happens to be in.

Where InfraSweep sits

InfraSweep is fully agentless, by design. You connect a read-only role (or a key) and it reads each cloud’s APIs, there is nothing to install, nothing running inside your workloads, and no write access at all. One grant, and it sweeps AWS, GCP, Azure, Alibaba, and OCI plus in-cluster Kubernetes for both misconfiguration and wasted spend in a single pass.

We’re deliberately clear about the boundary above: InfraSweep is the outside-in, posture-and-cost layer. It will tell you that image scanning is switched off, that a database is public, that a pod runs privileged, the configuration that creates workload risk, but it is not a runtime agent watching processes inside your containers. If you need that, run a dedicated runtime tool alongside it. What InfraSweep gives you is the fastest honest answer to “what’s exposed and what’s wasteful right now,” with every finding traced back to the raw API response it came from. The first scan is free.