auditing-s3-object-ownership-trust SKILL.md skillA
auditing-s3-object-ownership-trust from unboundcompute/security-agent-skills is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add unboundcompute/security-agent-skills/auditing-s3-object-ownership-trust@git:20260827.b5f41a4Pins git:20260827.b5f41a4 in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- unboundcompute/security-agent-skills
- Path
skills/auditing-s3-object-ownership-trust/SKILL.md- Versions recorded
- 1
- Latest version
- git:20260827.b5f41a4, committed Aug 27, 2026
- Size
- 9,175 bytes
- Repository stars
- 26
- License
- MIT
Audit object-storage ownership and per-object access for trust the bucket policy does not cover: an object uploaded by another account that keeps that uploader's ownership and ACL, a bucket where object ACLs still grant access despite a restrictive bucket policy, a cross-account write that lands an object the bucket owner cannot read or that carries a public grant, and a policy that scopes by prefix while an ACL on the object overrides it. Covers S3 and compatible stores where object…
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# Auditing S3 object-ownership trust: when the object, not the bucket, decides access Object stores let access be decided in more than one place, and that is where ownership trust breaks. A bucket policy is the central control most teams reason about, but each object also has an owner and, unless disabled, its own ACL, and a cross-account upload can land an object owned by the uploader rather than the bucket owner. The result is objects the bucket owner cannot fully control, ACLs that grant access the bucket policy meant to deny, and public grants riding on individual objects under a bucket that looks private. When a bucket receives objects from more than one principal, central governance is an assumption, not a fact. You audit these by checking who owns each object, whether object ACLs are still in force, and whether any object grants access the bucket policy did not intend. ## When to use - A bucket receives objects from more than one principal, including cross-account or third-party writers. - Access is meant to be governed centrally by the bucket policy, but object ACLs may still be enabled. …
Read the whole file at its exact version.
How to install
mdr add unboundcompute/security-agent-skills/auditing-s3-object-ownership-trust@sha256:2ad1367434279f8dThe line at the top of this page pins the label git:20260827.b5f41a4, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_h35j4ymeqobmse2g)
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Versions
The registry has recorded 1 version of this file, committed on Aug 27, 2026.
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (9175 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
unboundcompute/security-agent-skills · 26 stars · license MIT · pushed 2026-09-08 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_h35j4ymeqobmse2g GET https://markdownregistry.com/api/v1/resolve?ref=unboundcompute/security-agent-skills/auditing-s3-object-ownership-trust GET https://markdownregistry.com/api/v1/blob/2ad1367434279f8de73d9b52fdec61902f89c3b96ed8352add9688019840e3ce
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.