Add S3 bucket admin guardrails

[Chaos-among-us]

/claim #55

Scope

This is a bounded Phase 9 bucket-hardening guardrail slice for the S3 incident class described in #55.

• Add an IAM permissions-boundary template for StudentHub S3 service users that allows only the expected temp/permanent upload bucket object operations and explicitly denies bucket-admin controls such as lifecycle, CORS, policy, logging, replication, public-access-block, ACL, ownership, website, and versioning changes.
• Add a CloudFormation EventBridge/SNS template that alerts on CloudTrail S3 bucket-admin API calls against studenthub-* buckets.
• Add a local Node validation script so the protected deny/event coverage and no-secret template guardrails do not regress.
• Link the new guardrail doc from the README.

Safety Boundary

No live AWS/IAM calls, key rotation, bucket policy changes, candidate data, account IDs, access keys, secret keys, or private ARNs are included. The templates require maintainers to provide deployment-time values outside the repo.

Verification

node tools/check-aws-s3-guardrails.mjs
# AWS S3 guardrail templates passed validation.

git diff --check

[coderabbitai]

Warning

Rate limit exceeded

@Chaos-among-us has exceeded the limit for the number of commits that can be reviewed per hour. Please wait 36 minutes and 38 seconds before requesting another review.

You’ve run out of usage credits. Purchase more in the billing tab.

⌛ How to resolve this issue?

After the wait time has elapsed, a review can be triggered using the @coderabbitai review command as a PR comment. Alternatively, push new commits to this PR.

We recommend that you space out your commits to avoid hitting the rate limit.

🚦 How do rate limits work?

CodeRabbit enforces hourly rate limits for each developer per organization.

Our paid plans have higher rate limits than the trial, open-source and free plans. In all cases, we re-allow further reviews after a brief timeout.

Please see our FAQ for further information.

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 6eabd598-4fa1-4f17-9b61-9075671d3c24

📥 Commits

Reviewing files that changed from the base of the PR and between 7b023ff and 2e00d4d.

📒 Files selected for processing (5)

• README.md
• docs/security/aws-s3-bucket-change-alerts.cloudformation.json
• docs/security/aws-s3-guardrails.md
• docs/security/aws-s3-service-user-permissions-boundary.json
• tools/check-aws-s3-guardrails.mjs

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[Chaos-among-us]

Thanks for the bounty-pause update on #55. I won't start additional StudentHub work while the program is paused. This submitted PR remains green and available for review; please let me know if existing pre-pause submissions should wait here or be redirected to Discussions.

[BAWES]

Operations Check ⏰

This PR has been open for 23 days with no reviewer feedback. Are you still working on this or is it ready for review? Please post a status update.