[New Rule] Azure AKS API Server Proxying Request to Kubelet

[terrancedejesus]

Pull Request

Issue link(s):

• https://github.com/elastic/ia-trade-team/issues/725
• https://github.com/elastic/ia-trade-team/issues/875

Summary - What I changed

Adds a detection for non-system identity using the AKS (Azure Kubernetes Service) API server nodes/proxy subresource to reach a node's Kubelet API. Proxying through the API server bypasses direct network access and Kubelet TLS controls and can be used to run commands on nodes and move laterally across the cluster. Adds another detection for exec-specific API endpoints that are called from non-system identities.

How To Test

Query can be used in TRADE stack.

Checklist

• Added a label for the type of pr: bug, enhancement, schema, maintenance, Rule: New, Rule: Deprecation, Rule: Tuning, Hunt: New, or Hunt: Tuning so guidelines can be generated
• Added the meta:rapid-merge label if planning to merge within 24 hours
• Secret and sensitive material has been managed correctly
• Automated testing was updated or added to match the most common scenarios
• Documentation and comments were added for features that require explanation

Contributor checklist

• Have you signed the contributor license agreement?
• Have you followed the contributor guidelines?

[github-actions]

Rule: New - Guidelines

These guidelines serve as a reminder set of considerations when proposing a new rule.

Documentation and Context

• Detailed description of the rule.
• List any new fields required in ECS/data sources.
• Link related issues or PRs.
• Include references.

Rule Metadata Checks

• creation_date matches the date of creation PR initially merged.
• min_stack_version should support the widest stack versions.
• name and description should be descriptive and not include typos.
• query should be inclusive, not overly exclusive, considering performance for diverse environments. Non ecs fields should be added to non-ecs-schema.json if not available in an integration.
• min_stack_comments and min_stack_version should be included if the rule is only compatible starting from a specific stack version.
• index pattern should be neither too specific nor too vague, ensuring it accurately matches the relevant data stream (e.g., use logs-endpoint.process-* for process data).
• integration should align with the index. If the integration is newly introduced, ensure the manifest, schemas, and new_rule.yaml template are updated.
• setup should include the necessary steps to configure the integration.
• note should include any additional information (e.g. Triage and analysis investigation guides, timeline templates).
• tags should be relevant to the threat and align/added to the EXPECTED_RULE_TAGS in the definitions.py file.
• threat, techniques, and subtechniques should map to ATT&CK always if possible.

New BBR Rules

• building_block_type should be included if the rule is a building block and the rule should be located in the rules_building_block folder.
• bypass_bbr_timing should be included if adding custom lookback timing to the rule.

Testing and Validation

• Provide evidence of testing and detecting the expected threat.
• Check for existence of coverage to prevent duplication.

[Copilot]

Pull request overview

This PR adds two new Azure AKS detections focused on identifying abuse of the Kubernetes API server nodes/proxy subresource to access Kubelet endpoints (general proxying to Kubelet, plus high-signal command-execution endpoints), and updates the non-ECS schema to support the new fields referenced by these rules.

Changes:

• Added a lateral movement detection for non-system identities proxying through the AKS API server to reach node Kubelet.
• Added an execution-focused detection for proxy access to Kubelet command-execution endpoints (e.g., /exec, /run, /attach, /portForward).
• Extended logs-azure.platformlogs-* non-ECS schema with kube-audit flattened fields used by the new rules.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
rules/integrations/azure/lateral_movement_azure_aks_api_server_proxy_to_kubelet.toml	New rule for detecting non-system identities using nodes/proxy to reach Kubelet.
rules/integrations/azure/execution_azure_aks_kubelet_proxy_command_endpoint.toml	New rule for detecting nodes/proxy access to Kubelet exec/run/attach/portforward/cri endpoints.
detection_rules/etc/non-ecs-schema.json	Adds Azure platformlogs flattened kube-audit fields needed for querying/investigation fields.

[bryans3c]

LGTM! Maybe changing the rule name to potential or verifying response code or authorization?