[New Rule] Adding Coverage for AWS S3 Unauthenticated Bucket Listing by Rare Source

[terrancedejesus]

Pull Request

Issue link(s):

• https://github.com/elastic/ia-trade-team/issues/272

Summary - What I changed

Adding coverage for unauthenticated or "anonymous" bucket listing by rare source.

This rule detects attempts to list objects in an AWS S3 bucket from an unauthenticated source. This activity may indicate a misconfigured S3 bucket policy that allows unauthorized public access. Adversaries can exploit this misconfiguration to gather information about the bucket contents using tools or scripts.

The rule triggers when a rare IP address, not seen in the past 7 days, attempts to list S3 bucket objects without authentication.

How To Test

• https://github.com/elastic/pwncloud/pull/10

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?

[protectionsmachine]

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.

[Samirbous]

this looks more of a discovery ctivity vs collection, https://attack.mitre.org/techniques/T1619/

[w0rk3r]

++

[w0rk3r]

Suggested change

	S3 bucket without authentication. This is a [New
	Terms](https://www.elastic.co/guide/en/security/current/rules-ui-create.html#create-new-terms-rule) rule, which means it
	will only trigger once for each unique value of the `source.address` field that has not been seen making this API
	request within the last 7 days. This field contains the IP address of the source making the request.
	S3 bucket without authentication. This is a New Terms
	(https://www.elastic.co/guide/en/security/current/rules-ui-create.html#create-new-terms-rule) rule, which means it will
	only trigger once for each unique value of the `source.address` field that has not been seen making this API request
	within the last 7 days. This field contains the IP address of the source making the request.

Descriptions aren't rendered

[w0rk3r]

++