[New Rule] AWS CLI Command with Custom Endpoint URL

[terrancedejesus]

Pull Request

Issue link(s): https://github.com/elastic/ia-trade-team/issues/272

Summary - What I changed

Added a new linux detection rule for AWS CLI command execution where arguments include --endpoint-url. This is a new terms rule to only alert if the user on that endpoint has not been seen using this CLI command and specific argument in the last 10 days.

This stems from Sysdig research on adversary SCARLETEEL where a compromised EC2 instance with AWS cli installed was used to configure authentication to an external AWS environment or environment with applicable protocols for S3. Afterwards AWS CLI commands were executed for data exfiltration and tool installation however, pointed towards the remote site with the use of --endpoint-url.

If --endpoint-url is not used, the AWS CLI will attempt to interact with default AWS services and endpoint's based on either the compromised environment or default public AWS addresses. It is uncommon to leverage an external endpoint that is not default to AWS or custom to the target environment.

An ES|QL query was not used because of the truncated results it presents:

from logs-endpoint.events.process-*
| where @timestamp > now() - 10 days
| where event.category == "process" and process.name == "aws" and process.command_line RLIKE ".*--endpoint-url.*"
| eval date = DATE_FORMAT("yyyy-MM-dd", @timestamp)
| stats day_count = count_distinct(date) by user.name
| where day_count == 1

NOTE - The reason a Linux-based rule for Elastic Defend was created was due to no visibility from CloudTrail logs as AWS will only log the SOAP API calls for services like IAM and S3. As a result, there were no logs available for this from the AWS integration.

How To Test

NOTE - Global telemetry was checked for event.category: "process" and process.name: "aws" and process.args: "--endpoint-url" with no matches in the last 6 months for both SIEM and EDR.

Checklist

• [x] Added a label for the type of pr: bug, enhancement, schema, 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
• [x] 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.