ghostonbutterbread/403

403 Forbidden Bypass

Use only after a concrete 403 Forbidden response is observed on an in-scope endpoint.

This is a RAG-style child skill. Classify why the 403 exists, load one focused reference pack, then test the smallest safe bypass family.

Load Order

1. Read program scope, owned-account context, active live-testing policy, and the current agent's assigned surface.
2. Resolve $HARNESS_ROOT; default is /home/ryushe/projects/bug_bounty_harness.
3. Confirm the endpoint returned 403 in the current owned context and is agent-owned, assigned server/API surface, or tied to Ryushe's approved test account set.
4. Read $HARNESS_ROOT/prompts/403-context-pack.md.
5. Classify the lane:
   • path or route normalization -> $HARNESS_ROOT/skills/403/references/technique-packs/path-normalization.md
   • trusted route/client headers -> $HARNESS_ROOT/skills/403/references/technique-packs/trusted-headers.md
   • auth-state or owned-account comparison -> $HARNESS_ROOT/skills/403/references/technique-packs/auth-state.md
   • JWT/Bearer/cookie token controls authorization -> load /jwt-auth
6. Read $HARNESS_ROOT/prompts/403-playbook.md for deep review, stuck analysis, or report writing.
7. Route instead of duplicating:
   • JWT algorithm, signature, claim, key-source, or token format behavior -> /jwt-auth
   • broader header behavior -> /headers
   • WAF or bot enforcement -> /waf
   • object ownership or role boundary -> /access-control or /idor
   • broader mutation families -> /bypass

Workflow

1. Capture the baseline 403 with method, full URL, auth state, redirects, body length, response headers, and visible denial reason.
2. Record why the endpoint/resource is safe to probe.
3. Load one lane reference pack.
4. Run a bounded pass: baseline, one mutation family, compare, then stop or pivot.
5. Record the result as a note unless there is a security-relevant delta.

Proof Standard

Promote only when a mutation changes authorization, route reachability, protected behavior, or approved-account boundary in a reproducible way.

Do not promote cosmetic error changes, soft redirects, cache artifacts, public data, generic 403 pages, or caller-owned access.

Stop Conditions

Stop if the resource belongs to a real user or organization outside approved accounts, the endpoint is out of scope, the path is destructive, the block is rate-limit/WAF enforcement, or the next step would bypass billing, abuse controls, privacy controls, or explicit program policy.

Evidence

Write artifacts under $HARNESS_SHARED_BASE/{program}/agent_shared/findings/bypass/ or the owning finding lane.

Record full URLs, exact modified headers/path/method, auth state, account/resource ownership, response delta, loaded reference pack, and why the tested resource was safe to probe.