I've been conducting a preliminary evaluation of various cloud security platforms for my organization, and I keep encountering the term 'agentless' in Tenable's marketing materials, as well as those of several competitors. While I understand the high-level premise—that no software agent needs to be installed on the target assets—the technical implementation and practical implications remain somewhat opaque to me.
Could someone please explain, in concrete terms, how an agentless vulnerability assessment system like Tenable Cloud Security actually operates? I am particularly interested in the mechanics.
* What is the specific point of entry or connection method into a cloud service provider (e.g., AWS, Azure, GCP)? Is it solely through read-only API permissions granted to the Tenable service?
* Once connected, what does the system 'read' or 'analyze' to determine vulnerabilities? For instance, does it:
* Analyze cloud configuration metadata (security group rules, IAM policies, bucket permissions)?
* Interrogate the runtime state of provisioned virtual machines or container instances without an agent?
* Scan network-accessible services from within the cloud environment's network?
* How does this differ, in a practical workflow sense, from a traditional agent-based approach? I am trying to weigh the operational trade-offs.
My background is primarily in business intelligence and data visualization, where we connect to data sources via APIs and service accounts, so the concept of pulling configuration data for assessment is familiar. However, I am uncertain about the depth of analysis possible without a component running on the asset itself. A comparative breakdown of what is and is not detectable with an agentless approach in this context would be immensely helpful for my understanding.
Yeah, it's basically read-only API permissions. They get a service account with viewer/reader roles and then poll the cloud provider's APIs for configuration metadata. They're checking security groups, IAM policies, bucket ACLs, that sort of thing.
They can't see inside a running VM or container without an agent. That's the trade-off. It's good for catching misconfigurations, but if you want to know what's actually installed on the OS, you still need an agent. The marketing glosses over that part.
So it's just automated compliance checking against the cloud control plane. Not magic.
SQL is enough
Precisely. It's configuration auditing, not introspection.
The real gotcha is coverage gaps. Those read-only APIs fail or throttle during an incident, which is exactly when you need to know what changed. Seen teams get burned because their "agentless" coverage went dark during an outage.
Also, API lag means you're always looking at a stale snapshot. The cloud moves faster than your polling interval.
Prove it.