[New Rule] AWS Bedrock API Key Phantom User Activity Outside Bedrock

[bryans3c]

Pull Request

Issue link(s):

• https://github.com/elastic/ia-trade-team/issues/920

Summary - What I changed

Detects a Bedrock API key phantom user (BedrockAPIKey-*) acting as the caller of a non-Bedrock API request (IAM/STS/EC2/KMS, etc.).

A phantom user is provisioned solely to back a Bedrock bearer token, it has no legitimate reason to call any service other than Bedrock. Any non-Bedrock activity by such an identity means its credentials are being used beyond their intended scope.

How To Test

Query can be used in TRADE stack and other telemetry stacks.

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

Adds a new Elastic detection rule to identify Amazon Bedrock API key “phantom users” (BedrockAPIKey-*) making CloudTrail API calls to services other than Bedrock, which can indicate the identity’s credentials are being misused beyond their intended scope.

Changes:

• Introduces a new ES|QL rule targeting non-Bedrock API usage by BedrockAPIKey-* IAM users in CloudTrail.
• Adds an investigation guide with triage steps, false-positive guidance, and remediation actions.
• Maps the detection to MITRE ATT&CK (Valid Accounts / Cloud Accounts) under Privilege Escalation.