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352 lines
9.6 KiB
Markdown
352 lines
9.6 KiB
Markdown
# Enumeration from a Pod
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In a situation where you have managed to break into a Kubernetes Pod you could start enumerating the kubernetes environment from within.
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## Service Account Tokens
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Before continuing, if you don't know what is a service in Kubernetes I would suggest you to [**follow this link and read at least the information about Kubernetes architecture**](./#architecture)**.**
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**ServiceAccount** is an object managed by Kubernetes and used to provide an identity for processes that run in a pod.
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Every service account has a secret related to it and this secret contains a bearer token. This is a JSON Web Token \(JWT\), a method for representing claims securely between two parties.
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Usually in the directory `/run/secrets/kubernetes.io/serviceaccount` or `/var/run/secrets/kubernetes.io/serviceaccount` you can find the files:
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* **ca.crt**: It's the ca certificate to check kubernetes communications
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* **namespace**: It indicates the current namespace
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* **token**: It contains the **service token** of the current pod.
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The service account token is being signed by the key residing in the file **sa.key** and validated by **sa.pub**.
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Default location on **Kubernetes**:
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* /etc/kubernetes/pki
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Default location on **Minikube**:
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* /var/lib/localkube/certs
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Taken from the Kubernetes [documentation](https://kubernetes.io/docs/tasks/configure-pod-container/configure-service-account/#use-the-default-service-account-to-access-the-api-server):
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_“When you create a pod, if you do not specify a service account, it is automatically assigned the_ default _service account in the same namespace.”_
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### Hot Pods
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_**Hot pods are**_ pods containing a privileged service account token. A privileged service account token is a token that has permission to do privileged tasks such as listing secrets, creating pods, etc.
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## RBAC
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If you don't know what is **RBAC**, [**read this section**](./#cluster-hardening-rbac).
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## Enumeration CheatSheet
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To enumerate the environment you can upload the [**kubectl**](https://kubernetes.io/es/docs/tasks/tools/install-kubectl/) binary and use it. Also, using the **service** **token** obtained before you can manually access some endpoints of the **API Server**.
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In order to find the the IP of the API service check the environment for a variable called `KUBERNETES_SERVICE_HOST`.
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### Differences between `list` and `get` verbs
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With **`get`** permissions you can access the API:
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```text
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GET /apis/apps/v1/namespaces/{namespace}/deployments/{name}
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```
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If you have the **`list`** permission, you are allowed to execute these API requests:
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```bash
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#In a namespace
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GET /apis/apps/v1/namespaces/{namespace}/deployments
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#In all namespaces
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GET /apis/apps/v1/deployments
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```
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If you have the **`watch`** permission, you are allowed to execute these API requests:
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```text
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GET /apis/apps/v1/deployments?watch=true
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GET /apis/apps/v1/watch/namespaces/{namespace}/deployments?watch=true
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GET /apis/apps/v1/watch/namespaces/{namespace}/deployments/{name} [DEPRECATED]
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GET /apis/apps/v1/watch/namespaces/{namespace}/deployments [DEPRECATED]
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GET /apis/apps/v1/watch/deployments [DEPRECATED]
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```
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They open a streaming connection that returns you the full manifest of a Deployment whenever it changes \(or when a new one is created\).
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{% hint style="danger" %}
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The following `kubectl` commands indicates just how to list the objects. If you want to access the data you need to use `describe` instead of `get`
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{% endhint %}
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### Get namespaces
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{% tabs %}
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{% tab title="kubectl" %}
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```bash
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./kubectl get namespaces
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```
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{% endtab %}
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{% tab title="API" %}
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```bash
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curl -v -H "Authorization: Bearer <jwt_token>" \
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https://<Kubernetes_API_IP>:<port>/api/v1/namespaces/
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```
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{% endtab %}
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{% endtabs %}
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### Get secrets
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{% tabs %}
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{% tab title="kubectl" %}
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```text
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./kubectl get secrets -o yaml
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./kubectl get secrets -o yaml -n custnamespace
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```
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{% endtab %}
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{% tab title="API" %}
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```bash
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curl -v -H "Authorization: Bearer <jwt_token>" \
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https://<Kubernetes_API_IP>:<port>/api/v1/namespaces/default/secrets/
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curl -v -H "Authorization: Bearer <jwt_token>" \
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https://<Kubernetes_API_IP>:<port>/api/v1/namespaces/custnamespace/secrets/
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```
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{% endtab %}
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{% endtabs %}
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If you can read secrets you can use the following lines to get the privileges related to each to token:
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```bash
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for token in `./kubectl describe secrets -n kube-system | grep "token:" | cut -d " " -f 7`; do echo $token; ./kubectl --token $token auth can-i --list; echo; done
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```
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### Get Current Privileges
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{% tabs %}
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{% tab title="kubectl" %}
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```bash
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./kubectl auth can-i --list #Get privileges in general
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./kubectl auth can-i --list -n custnamespace #Get privileves in custnamespace
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```
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{% endtab %}
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{% endtabs %}
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**Once you know which privileges** you have, check the following page to figure out **if you can abuse them** to escalate privileges:
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{% page-ref page="hardening-roles-clusterroles.md" %}
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### Get Current Context
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{% tabs %}
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{% tab title="Kubectl" %}
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```text
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kubectl config current-context
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```
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{% endtab %}
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{% endtabs %}
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### Get deployments
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{% tabs %}
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{% tab title="kubectl" %}
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```text
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./kubectl get deployments
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./kubectl get deployments -n custnamespace
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```
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{% endtab %}
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{% tab title="API" %}
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```bash
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curl -v -H "Authorization: Bearer <jwt_token>" \
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https://<Kubernetes_API_IP>:<port>/api/v1/namespaces/default/deployments/
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curl -v -H "Authorization: Bearer <jwt_token>" \
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https://<Kubernetes_API_IP>:<port>/api/v1/namespaces/custnamespace/deployments/
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```
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{% endtab %}
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{% endtabs %}
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### Get pods
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{% tabs %}
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{% tab title="kubectl" %}
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```text
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./kubectl get pods
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./kubectl get pods -n custnamespace
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```
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{% endtab %}
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{% tab title="API" %}
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```bash
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curl -v -H "Authorization: Bearer <jwt_token>" \
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https://<Kubernetes_API_IP>:<port>/api/v1/namespaces/default/pods/
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curl -v -H "Authorization: Bearer <jwt_token>" \
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https://<Kubernetes_API_IP>:<port>/api/v1/namespaces/custnamespace/pods/
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```
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{% endtab %}
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{% endtabs %}
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### Get services
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{% tabs %}
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{% tab title="kubectl" %}
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```text
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./kubectl get services
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./kubectl get services -n custnamespace
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```
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{% endtab %}
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{% tab title="API" %}
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```bash
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curl -v -H "Authorization: Bearer <jwt_token>" \
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https://<Kubernetes_API_IP>:<port>/api/v1/namespaces/default/services/
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curl -v -H "Authorization: Bearer <jwt_token>" \
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https://<Kubernetes_API_IP>:<port>/api/v1/namespaces/custnamespace/services/
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```
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{% endtab %}
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{% endtabs %}
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### Get nodes
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{% tabs %}
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{% tab title="kubectl" %}
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```text
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./kubectl get nodes
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```
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{% endtab %}
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{% tab title="API" %}
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```bash
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curl -v -H "Authorization: Bearer <jwt_token>" \
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https://<Kubernetes_API_IP>:<port>/api/v1/nodes/
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```
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{% endtab %}
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{% endtabs %}
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### Get daemonsets
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{% tabs %}
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{% tab title="kubectl" %}
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```text
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./kubectl get daemonsets
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```
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{% endtab %}
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{% tab title="API" %}
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```bash
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curl -v -H "Authorization: Bearer <jwt_token>" \
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https://<Kubernetes_API_IP>:<port>/apis/extensions/v1beta1/namespaces/default/daemonsets
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```
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{% endtab %}
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{% endtabs %}
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### Get "all"
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{% tabs %}
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{% tab title="kubectl" %}
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```text
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./kubectl get all
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```
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{% endtab %}
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{% endtabs %}
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## **Pod Breakout**
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**If you are lucky enough you may be able to escape from it to the node:**
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{% page-ref page="../../linux-unix/privilege-escalation/docker-breakout.md" %}
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## Sniffing
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By default there isn't any encryption in the communication between pods .Mutual authentication, two-way, pod to pod.
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#### Create a sidecar proxy app <a id="create-a-sidecar-proxy-app"></a>
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Create your .yaml
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```bash
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kubectl run app --image=bash --comand -oyaml --dry-run=client > <appName.yaml> -- shj -c 'ping google.com'
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```
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Edit your .yaml and add the uncomment lines:
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```yaml
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#apiVersion: v1
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#kind: Pod
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#metadata:
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# name: security-context-demo
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#spec:
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# securityContext:
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# runAsUser: 1000
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# runAsGroup: 3000
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# fsGroup: 2000
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# volumes:
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# - name: sec-ctx-vol
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# emptyDir: {}
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# containers:
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# - name: sec-ctx-demo
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# image: busybox
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command: [ "sh", "-c", "apt update && apt install iptables -y && iptables -L && sleep 1h" ]
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securityContext:
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capabilities:
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add: ["NET_ADMIN"]
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# volumeMounts:
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# - name: sec-ctx-vol
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# mountPath: /data/demo
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# securityContext:
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# allowPrivilegeEscalation: true
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```
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See the logs of the proxy:
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```bash
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kubectl logs app -C proxy
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```
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More info at: [https://kubernetes.io/docs/tasks/configure-pod-container/security-context/](https://kubernetes.io/docs/tasks/configure-pod-container/security-context/)
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## Search vulnerable network services
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As you are inside the Kubernetes environment, if you cannot escalate privileges abusing the current pods privileges and you cannot escape from the container, you should **search potential vulnerable services.**
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### Services
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**For this purpose, you can try to get all the services of the kubernetes environment:**
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```text
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kubectl get svc –all-namespaces
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```
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### Scanning
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The following Bash script \(taken from a [Kubernetes workshop](https://github.com/calinah/learn-by-hacking-kccn/blob/master/k8s_cheatsheet.md)\) will install and scan the IP ranges of the kubernetes cluster:
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```bash
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sudo apt-get update
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sudo apt-get install nmap
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nmap-kube ()
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{
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nmap --open -T4 -A -v -Pn -p 443,2379,8080,9090,9100,9093,4001,6782-6784,6443,8443,9099,10250,10255,10256 "${@}"
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}
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nmap-kube-discover () {
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local LOCAL_RANGE=$(ip a | awk '/eth0$/{print $2}' | sed 's,[0-9][0-9]*/.*,*,');
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local SERVER_RANGES=" ";
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SERVER_RANGES+="10.0.0.1 ";
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SERVER_RANGES+="10.0.1.* ";
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SERVER_RANGES+="10.*.0-1.* ";
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nmap-kube ${SERVER_RANGES} "${LOCAL_RANGE}"
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}
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nmap-kube-discover
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```
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## References
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{% embed url="https://www.cyberark.com/resources/threat-research-blog/kubernetes-pentest-methodology-part-3" %}
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