hunt-cors

Hunt CORS Misconfiguration — origin-reflection with credentials, null-origin trust, subdomain-regex bypass (unanchored vs unescaped-dot vs prefix-only), pre-flight (OPTIONS) gating bypass, postMessage origin checks. High only when an attacker-controlled origin can perform a CREDENTIALED cross-origin read of sensitive data and you have proven it in a browser. Use when testing API endpoints, SPAs, or any app emitting Access-Control-* headers.

Quality

88%

Does it follow best practices?

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Securityby

Critical

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Quality

Content

77%

Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.

A highly actionable, well-sequenced hunting methodology with strong validation discipline, weakened only by repeated rule restatements and the absence of any external file structure for a document of this length.

Suggestions

De-duplicate the 'ACAO:* + credentials' and 'ACAC alone proves nothing' rules: state them once in 'Validation discipline' and reference back instead of repeating full explanations in Phase 2 and Phase 5a.

Extract the Phase 3 regex-bypass table and the Phase 5 browser PoCs into reference files (e.g. references/regex-bypasses.md, references/browser-pocs.md) with one-level-deep links from the body to improve progressive disclosure.

Tighten the 'What actually pays' section so it points forward to the phases rather than re-deriving rules that are restated later.

Dimension	Reasoning	Score
Conciseness	Mostly efficient and dense with specialized knowledge, but the same validation rules ('ACAO: * + credentials = not a finding', 'ACAC alone proves nothing', 'browser proof mandatory') are repeated across 'What actually pays', Phase 2, Phase 5a, and 'Validation discipline', adding redundant tokens.	2 / 3
Actionability	Copy-paste-ready curl probes, bash loops, HTML/iframe browser PoCs, and nuclei/corsy commands — fully executable rather than pseudocode or abstract direction.	3 / 3
Workflow Clarity	Clear Phase 1–6 sequence with explicit validation checkpoints ('Browser PoCs (the only thing that proves impact)', 'Validation discipline' checklist) and feedback loops ('If you see BLOCKED ... it is NOT a valid finding').	3 / 3
Progressive Disclosure	Well-sectioned into headers and phases, but it is a 280-line monolithic document with no bundle files or external references; the regex-bypass table and browser PoCs could be split into separate referenced files. The simple-skill (<50 lines) exception does not apply.	2 / 3
	Total	10 / 12 Passed

Description

100%

Based on the skill's description, can an agent find and select it at the right time? Clear, specific descriptions lead to better discovery.

A highly specific, well-triggered description that clearly states both the capability and the use conditions, with no first/second-person voice issues beyond the standard accepted 'Use when...' form.

Dimension	Reasoning	Score
Specificity	Lists multiple concrete actions — 'origin-reflection with credentials, null-origin trust, subdomain-regex bypass (unanchored vs unescaped-dot vs prefix-only), pre-flight (OPTIONS) gating bypass, postMessage origin checks' — each a specific technique rather than vague language.	3 / 3
Completeness	Explicitly answers both what (the named CORS bypass classes) and when via an explicit 'Use when testing API endpoints, SPAs, or any app emitting Access-Control-* headers' clause.	3 / 3
Trigger Term Quality	Natural pentester keywords are well covered — 'CORS Misconfiguration', 'API endpoints', 'SPAs', 'Access-Control-* headers' — terms a user would actually say when needing this skill.	3 / 3
Distinctiveness Conflict Risk	Tightly scoped to CORS misconfiguration with distinct, non-generic triggers; unlikely to fire for unrelated skills.	3 / 3
	Total	12 / 12 Passed

Validation

93%

Warnings & errors only

Checks the skill against the spec for correct structure and formatting. All validation checks must pass before discovery and implementation can be scored.

Validation — 15 / 16 Passed

Validation for skill structure

Criteria	Description	Result
frontmatter_unknown_keys	Unknown frontmatter key(s) found; consider removing or moving to metadata	Warning

	Total	15 / 16 Passed

Repository: elementalsouls/Claude-BugHunter
Path: skills/hunt-cors/SKILL.md
Commit: 6b9c96e

Reviewed: 3 days ago

Table of Contents

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