Quick answer: Kubernetes and container penetration testing is a security service that examines an organization's container platform, that is its Docker images, Kubernetes clusters and runtime, through an attacker's eyes. The most common flaws are privileged containers running with excessive capabilities, misconfigured RBAC roles, kubelet interfaces with authentication disabled and vulnerable base images. These flaws often turn the compromise of a single container into the compromise of the whole cluster. DSET runs this test with its local AI engine KAOS and verifies every finding with a working proof.

Container technologies accelerated application delivery, but they brought a new attack surface that most organizations are not used to. When you picture a single server on a virtual machine, a Kubernetes cluster instead has dozens of nodes, hundreds of containers and the network and privilege relations between them. This article explains what Kubernetes and container penetration testing is, which flaws it targets and the DSET and KAOS approach.

What is Kubernetes and container penetration testing

Kubernetes and container penetration testing tests the flaws of a container based platform through controlled attacks. The test has three main layers. The first layer is the container image itself, that is vulnerable libraries inside the image and secrets embedded in the image. The second layer is the runtime, that is whether an attacker can escape a container and reach the host node. The third layer is the cluster control plane, that is the Kubernetes API server, RBAC roles and service accounts. When these three layers are not tested together, a complete security picture does not emerge.

Which flaws it targets

The flaws of container platforms are often found not in code but in configuration. When a developer puts a container in privileged mode for convenience or grants broad rights to a service account, a path opens for the attacker.

Flaw class What it means Typical result
Privileged container The container reaches host capabilities Container escape, node takeover
Misconfigured RBAC A service account is given excessive rights Cluster wide privilege escalation
Exposed kubelet or API The management interface is reached without authentication Running containers, reading secrets
Vulnerable base image The image carries a library with a known flaw Remote code execution
Secret embedded in image A key or password is written into the image Credential leakage

The essence of the table is this: in a container platform the smallest misconfiguration lays the ground for an attacker to spread from a single container to the whole cluster. This spreading logic resembles lateral movement in a classic internal network; indeed the topic of lateral movement with pivoting and tunneling applies here too.

Why container escape is critical

Containers share the same kernel. A virtual machine escape requires breaking the hardware virtualization layer, while a container escape often exploits only a wrong configuration, for example the host file system mounted into the container or an extra kernel capability. When an attacker escapes a container and reaches the host node, they reach the secrets of all containers on that node and that node's rights inside the cluster. For this reason the test centers on a single question: how dangerous is a compromised container for the rest of the cluster.

Relation to cloud and source code testing

Container security does not stand alone. Clusters often run on AWS, Azure or Google Cloud, so cluster security and cloud identity management intertwine; for this complementary view our cloud penetration testing service comes in. On the other side a vulnerable base image often comes from software dependencies, which connects directly to source code security review and SCA and to supply chain attacks and software dependency security.

When is it done

The right practice is to test before a container platform goes live, when the cluster architecture changes significantly and at regular intervals. Every organization moving to a new microservice architecture should examine its cluster configuration with an independent eye before the move. The scope must be drawn clearly before the test, for which the penetration testing preparation and scoping guide is the reference point.

The KAOS and DSET approach

DSET runs Kubernetes and container penetration testing with its local AI engine KAOS. KAOS scans container images for vulnerable libraries and embedded secrets, examines cluster configuration for RBAC and privileged containers and reports every flaw it finds with a working proof, under the principle of proof based verification. The difference is this: it does not settle for saying a configuration is theoretically risky, it proves that the risk actually leads to container escape or privilege escalation. After a finding is verified, retest and remediation verification is applied to see that the fix works.

Frequently asked questions

Are container scanning and container penetration testing the same thing? No, the two differ in depth. Container scanning lists the known vulnerabilities inside an image, but it does not say whether that vulnerability can be exploited inside a real cluster. Penetration testing instead uses the flaw like an attacker and proves its result, for example showing that it escaped a container and reached the host node. Scanning produces an inventory, penetration testing proves the real impact.

I use a managed Kubernetes service, is a test still needed? Yes. In a managed Kubernetes service part of the control plane belongs to the provider, but the configuration of your workloads, your RBAC roles, your service accounts and your images are your responsibility. The vast majority of attacks happen in this layer that is your responsibility, so a managed service does not make the test unnecessary.

Can the running cluster be harmed during the test? In a well planned test no. Which namespaces and which workloads will be tested and whether destructive operations will be done are set in advance by contract. When possible the test is run on a copy of the production cluster, so the live service is not affected.

Sources

To examine your Kubernetes clusters and container platform with a proof based test, contact DSET. We provide container and Kubernetes penetration testing and consulting from our Ankara Hacettepe Teknokent laboratory.