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Kubernetes User Exec into Pod

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Kubernetes User Exec into Pod

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This rule detects a user attempt to establish a shell session into a pod using the exec command. Using the exec command in a pod allows a user to establish a temporary shell session and execute any process/commands in the pod. An adversary may call bash to gain a persistent interactive shell which will allow access to any data the pod has permissions to, including secrets.

Rule type: query

Rule indices:

logs-kubernetes.*

Severity: medium

Risk score: 47

Runs every: 5 minutes

Searches indices from: now-6m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

Tags:

Elastic
Kubernetes
Continuous Monitoring
Execution

Version: 200 (version history)

Added (Elastic Stack release): 8.3.0

Last modified (Elastic Stack release): 8.6.0

Rule authors: Elastic

Rule license: Elastic License v2

Potential false positives

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An administrator may need to exec into a pod for a legitimate reason like debugging purposes. Containers built from Linux and Windows OS images, tend to include debugging utilities. In this case, an admin may choose to run commands inside a specific container with kubectl exec ${POD_NAME} -c ${CONTAINER_NAME} — ${CMD} ${ARG1} ${ARG2} … ${ARGN}. For example, the following command can be used to look at logs from a running Cassandra pod: kubectl exec cassandra --cat /var/log/cassandra/system.log . Additionally, the -i and -t arguments might be used to run a shell connected to the terminal: kubectl exec -i -t cassandra — sh

Investigation guide

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Rule query

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event.dataset : "kubernetes.audit_logs" and
kubernetes.audit.annotations.authorization_k8s_io/decision:"allow"
and kubernetes.audit.verb:"create" and
kubernetes.audit.objectRef.resource:"pods" and
kubernetes.audit.objectRef.subresource:"exec"

Threat mapping

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Framework: MITRE ATT&CK^TM

Tactic:
- Name: Execution
- ID: TA0002
- Reference URL: https://attack.mitre.org/tactics/TA0002/
Technique:
- Name: Container Administration Command
- ID: T1609
- Reference URL: https://attack.mitre.org/techniques/T1609/

Rule version history

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Version 200 (8.6.0 release)

Updated query, changed from:

kubernetes.audit.objectRef.resource:"pods" and
kubernetes.audit.objectRef.subresource:"exec"

Version 100 (8.5.0 release)

Updated query, changed from:

kubernetes.audit.objectRef.resource:"pods" and
kubernetes.audit.objectRef.subresource:"exec"

Version 3 (8.4.0 release)

Updated query, changed from:

event.dataset:"kubernetes.audit_logs" and
kubernetes.audit.objectRef.resource:"pods" and
kubernetes.audit.objectRef.subresource:"exec"

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