rspec/rules/S5849/kubernetes/rule.adoc

Setting capabilities can lead to privilege escalation and container escapes.

Linux capabilities allow you to assign narrow slices of ``++root++``'s permissions to processes. A thread with capabilities bypasses the normal kernel security checks to execute high-privilege actions such as mounting a device to a directory, without requiring additional root privileges.

In a container, capabilities might allow to access resources from the host system which can result in container escapes. For example, with the capability ``++SYS_ADMIN++`` an attacker might be able to mount devices from the host system inside of the container.


== Ask Yourself Whether

Capabilities are granted:

* To a process that does not require all capabilities to do its job.
* To a not trusted process.

There is a risk if you answered yes to any of those questions.


== Recommended Secure Coding Practices

Capabilities are high privileges, traditionally associated with superuser (root), thus make sure that the most restrictive and necessary capabilities are assigned.


== Sensitive Code Example

[source,yaml]
----
apiVersion: v1
kind: Pod
metadata:
  name: example
spec:
  containers:
  - image: k8s.gcr.io/test-webserver
    name: test-container
    securityContext:
      capabilities:
        add: ["SYS_ADMIN"] # Sensitive
----

== Compliant Solution

[source,yaml]
----
apiVersion: v1
kind: Pod
metadata:
  name: example
spec:
  containers:
  - image: k8s.gcr.io/test-webserver
    name: test-container
----


== See

* CWE - https://cwe.mitre.org/data/definitions/250[CWE-250 - Execution with Unnecessary Privileges]
* CWE - https://cwe.mitre.org/data/definitions/266[CWE-266 -  Incorrect Privilege Assignment]
* https://kubernetes.io/docs/tasks/configure-pod-container/security-context/[Kubernetes Documentation] - Configure a Security Context for a Pod or Container
* https://man7.org/linux/man-pages/man7/capabilities.7.html[Linux manual page] - capabilities(7)


ifdef::env-github,rspecator-view[]

'''
== Implementation Specification
(visible only on this page)

=== Message

Make sure setting capabilities is safe here.


'''
== Comments And Links
(visible only on this page)



endif::env-github,rspecator-view[]