About Kubernetes security posture scanning

This page describes Kubernetes security posture scanning, which is a capability of the security posture dashboard that detects common security configuration concerns, actionable security bulletins in your Kubernetes workloads, and active threats in your GKE Enterprise clusters.

To enable and use Kubernetes security posture scanning, see the following resources:

Kubernetes security posture scanning provides the following functionality:

Pricing

  • Standard tier: Offered at no extra charge in GKE.
  • Advanced tier: Included in GKE Enterprise.

Entries added to Cloud Logging are subject to Cloud Logging pricing.

About workload configuration auditing

The workloads that you deploy on GKE should have a hardened configuration that limits their attack surface. Checking workloads across clusters for configuration issues can be difficult to do manually at scale. You can use the security posture dashboard to automatically audit the configuration of all your running workloads across multiple clusters and return actionable, scored results and opinionated recommendations to improve your security posture.

Workload configuration auditing checks each deployed workload against a subset of policies in the Pod Security Standards. Workload configuration auditing happens on Google's infrastructure and doesn't use compute resources on your nodes.

Benefits of workload configuration auditing

  • Automate detection of known configuration concerns across all workloads.
  • Get actionable recommendations to improve security posture.
  • Use the Google Cloud console to get a high-level view of configuration concerns.
  • Use Logging to get an auditable trail of concerns for better reporting and observability.

How workload configuration auditing works

For each eligible deployed workload, GKE continuously scans the workload's specification and compares the fields and values to the controls defined in the underlying security policy. For example, a Pod with spec.containers.securityContext.privileged=true violates the Baseline Pod Security Standard, and a Pod with the spec.securityContext.runAsNonRoot field set to false violates the Restricted standard. For a list of the security policies that GKE checks, refer to What does workload configuration auditing check?.

After scanning and discovering concerns, GKE rates the severity of discovered configuration issues based on the built-in security hardening measures. GKE assigns a severity rating that can inform the speed with which you respond to the concern. The Google Cloud console displays the results and recommended actions you can take to fix the concerns. GKE also adds entries to Cloud Logging for tracing and auditing.

What does workload configuration auditing check?

Concern Fields Allowed values Severity

Host namespaces

Pods that share host namespaces allow Pod processes to communicate with host processes and gather host information, which could lead to a container escape.
  • spec.hostNetwork
  • spec.hostIPC
  • spec.hostPID
  • Undefined or nil
  • false
 High

Privileged containers

Privileged containers allow nearly unrestricted host access. They share namespaces with the host, and lack control group, seccomp, AppArmor, and capability restrictions.
  • spec.containers[*].securityContext.privileged
  • spec.initContainers[*].securityContext.privileged
  • spec.ephemeralContainers[*].securityContext.privileged
  • Undefined or nil
  • false
 High

Host port access

Exposing a host port to a container potentially allows the container to intercept network traffic to a host service using that port or to bypass network access control rules, such as the rules in a NetworkPolicy.
  • spec.containers[*].ports[*].hostPort
  • spec.initContainers[*].ports[*].hostPort
  • spec.ephemeralContainers[*].ports[*].hostPort
  • Undefined or nil
  • 0
 High

Non-default capabilities

A container has assigned capabilities that could allow a container escape.
  • spec.containers[*].securityContext.capabilities.add
  • spec.initContainers[*].securityContext.capabilities.add
  • spec.ephemeralContainers[*].securityContext.capabilities.add
  • Undefined or nil
  • AUDIT_WRITE
  • CHOWN
  • DAC_OVERRIDE
  • FOWNER
  • FSETID
  • KILL
  • MKNOD
  • NET_BIND_SERVICE
  • SETFCAP
  • SETGID
  • SETPCAP
  • SETUID
  • SYS_CHROOT
 Medium

Mounting host path volumes

hostPath volumes mount files or directories from the host. These volumes present security risks that could lead to container escape.

 spec.volumes[*].hostPath Undefined or nil Medium

Non-default /proc mask

The default /proc mount type masks certain paths in /proc to avoid exposure of paths that could lead to information leakage or container escape. Using a non-default type increases these risks.
  • spec.containers[*].securityContext.procMount
  • spec.initContainers[*].securityContext.procMount
  • spec.ephemeralContainers[*].securityContext.procMount
  • Undefined or nil
  • Default
 Medium

Unsafe sysctls mask

A Pod can be configured to allow modification of unsafe kernel parameters using the /proc/sys virtual file system. Unsafe parameters don't support namespacing, don't properly isolate their effect between Pods, could harm the node's health, or might allow the Pod to gain resources beyond its limits.

 spec.securityContext.sysctls[*].name
  • Undefined or nil
  • kernel.shm_rmid_forced
  • net.ipv4.ip_local_port_range
  • net.ipv4.ip_unprivileged_port_start
  • net.ipv4.tcp_syncookies
  • net.ipv4.ping_group_range
 Medium

Running as non-root

You can explicitly allow a container to run as the root user if the runAsUser or the USER directive in the image specifies the root user. The lack of preventive security controls when running as the root user increases the risk of container escape.
  • spec.securityContext.runAsNonRoot
  • spec.containers[*].securityContext.runAsNonRoot
  • spec.initContainers[*].securityContext.runAsNonRoot
  • spec.ephemeralContainers[*].securityContext.runAsNonRoot
 true Medium

Privilege escalation

A container can be explicitly configured to allow privilege escalation on execution. This permits a process created within the container by executing a set-user-id, set-group-id, or file capability executable to gain the privileges specified by the executable. The lack of preventive security control increases the risk of container escape.
  • spec.containers[*].securityContext.allowPrivilegeEscalation
  • spec.initContainers[*].securityContext.allowPrivilegeEscalation
  • spec.ephemeralContainers[*].securityContext.allowPrivilegeEscalation
 false Medium

Unconfined AppArmor profile

A container can be explicitly configured to be unconfined by AppArmor. This ensures that no AppArmor profile is applied to the container and is thus not constrained by them. The disabled preventive security control increases the risk of container escape.

 metadata.annotations["container.apparmor.security.beta.kubernetes.io/*"] false Low

Additionally, GKE checks for any RBAC RoleBindings or ClusterRoleBindings that reference one of the following users or groups:

  • system:anonymous
  • system:authenticated
  • system:unauthenticated

If any RBAC bindings that reference these users or groups exist, a finding named Effectively Anonymous Users Granted GKE Cluster Access with a severity of Medium appears in the security posture dashboard. These users and groups are effectively anonymous and shouldn't be used in RoleBindings or ClusterRoleBindings. For more information, see Avoid default roles and groups.

About security bulletin surfacing

When a vulnerability is discovered in GKE, we patch the vulnerability and publish a security bulletin for the vulnerability. For information about identification, patching, and timelines, refer to GKE security patching.

The security posture dashboard displays security bulletins that affect your clusters, workloads, and Standard mode node pools. This feature is a part of the Kubernetes security posture capability of the security posture dashboard and is automatically enabled when you create an Autopilot or Standard cluster. To enable Kubernetes security posture scanning, use the instructions in Automatically audit workloads for configuration issues.

The Google Cloud console displays details such as affected clusters, versions, and recommended patch versions for upgrades to mitigate the vulnerability. You only see bulletins for which a mitigation is available in your cluster's Google Cloud region or zone.

To view bulletins for clusters that you enrolled in Kubernetes security posture scanning, go to the security posture dashboard:

Go to Security Posture

Any available bulletins that affect your environment appear in the Security bulletins section.

About GKE threat detection

GKE threat detection scans your enrolled clusters' audit logs for active threats and provides recommended mitigation actions. GKE threat detection is powered by the Security Command Center Event Threat Detection service. For more information, in the GKE Enterprise documentation, see About GKE threat detection.

What's next