[New Rule] Adding Coverage for `AWS S3 Static Site JavaScript File Uploaded`

[terrancedejesus]

Pull Request

Issue link(s):

• https://github.com/elastic/ia-trade-team/issues/585

Summary - What I changed

Adds coverage for static JS file uploads to AWS S3 buckets. This is a signal for potential web content manipulation via a compromised identity as noted in Safe{Wallet} attack.

"This rule detects when a JavaScript file is uploaded or accessed in an S3 static site directory (static/js/) by an IAM user or assumed role. This can indicate suspicious modification of web content hosted on S3, such as injecting malicious scripts into a static website frontend."

Additional Information:

• Sites, such as Safe{Wallet}'s frontend interface for transactions are hosted in S3 buckets as static websites.
• Websites are often built via JavaScript libraries like React and then pushed to the S3 bucket
• Adversaries whom have access may download and modify the contents of the website to inject malicious code
• Typically authN is done via stolen credentials but leveraging AWS CLI or Boto3 (SDK)
• It is expected for this to have false-positives, however identity types have been scoped to IAMUser and Role as well as only when files with .js are uploaded.
• We specifically ignore IaC user agents as it is the only fingerprint that identifies it was done via IaC. Additionally, it is not uncommon for developers to adjust the source code of the app, re-build and leverage Terraform to push it back up or leverage CloudFront.

How To Test

Testing was done via an OnWeek project for replicating ByBit attack behaviors. Query syntax is accurate.

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[bot]]

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.