Probing Dangerous HTTP Methods

Overview

Most HTTP methods beyond GET/POST/HEAD are vestigial — leftover from WebDAV authoring stacks of the early 2000s, debugging features in legacy servers, or default-enabled methods nobody disabled at install time. Each enabled method that the application doesn't use is an attack surface: TRACE enables Cross-Site Tracing (XST), PUT enables arbitrary file upload to unprotected paths, CONNECT enables proxy abuse against internal services, WebDAV enables directory manipulation.

This skill probes the canonical method set and grades each based on its presence and response.

When the skill produces findings

Finding	Severity	Threshold	Affected control
TRACE method enabled	HIGH	TRACE returns 200 with request echo	OWASP A05:2021, CWE-693
PUT method enabled outside API path	HIGH	PUT returns 200/201/204 on non-API path	CWE-434
DELETE method enabled outside API path	HIGH	DELETE returns 200/204 on non-API path	CWE-285
CONNECT method enabled	CRITICAL	CONNECT returns 200 (proxy abuse open)	CWE-441
DEBUG method enabled	HIGH	DEBUG returns response (legacy IIS / dev servers)	CWE-489
WebDAV methods enabled (PROPFIND/MKCOL/COPY/MOVE)	HIGH	Any return 207 or 201	CWE-538
Allow header discloses unused methods	LOW	OPTIONS Allow includes methods app doesn't use	CWE-200
OPTIONS returns full method enumeration	LOW	Allow:* or broad list	CWE-200

Prerequisites

• Python 3.9+
• Authorization for non-local targets

Instructions

Step 1 — Confirm authorization

"Do you have authorization to perform HTTP method probing on this
 target? I need confirmation before proceeding."

Step 2 — Run the scanner

python3 ${CLAUDE_PLUGIN_ROOT}/skills/probing-dangerous-http-methods/scripts/probe_methods.py \
    https://example.com \
    --authorized

Options:

Usage: probe_methods.py URL [OPTIONS]

Options:
  --authorized      Attest authorization (required)
  --output FILE
  --format FMT      json | jsonl | markdown (default: markdown)
  --min-severity SEV (default: info)
  --timeout SECS
  --is-api          Treat URL as API endpoint (relaxes PUT/DELETE checks)

By default the scanner treats the URL as a non-API endpoint where PUT/DELETE should return 405. With --is-api, those methods are expected and don't trigger findings — only the auth checks behind them matter (delegated to other skills).

Step 3 — Interpret findings

CRITICAL CONNECT-open = your reverse proxy is letting external clients connect to arbitrary internal hosts (e.g., metadata endpoints in AWS/GCP). Ship same-hour fix.

HIGH TRACE = XST attack open. Combined with any XSS, attacker can read HttpOnly cookies via XHR. Ship-within-sprint fix.

HIGH WebDAV = file upload + manipulation surface. Audit references/ PLAYBOOK.md § disabling WebDAV.

Step 4 — Cross-skill chaining

After this skill, suggest:

• auditing-cors-policy (#3) if Allow-Methods:* surfaced
• detecting-debug-endpoints (#7) for the broader exposed-feature audit if DEBUG/TRACE both fired

Examples

Example 1 — Post-deploy method audit

User: "We rolled out a new ALB config. Audit the method surface."

python3 ${CLAUDE_PLUGIN_ROOT}/skills/probing-dangerous-http-methods/scripts/probe_methods.py \
    https://api.example.com \
    --authorized --is-api --min-severity high

Example 2 — TRACE / XST audit after XSS finding

User: "Found XSS on /search; checking if XST chain is possible."

python3 ${CLAUDE_PLUGIN_ROOT}/skills/probing-dangerous-http-methods/scripts/probe_methods.py \
    https://example.com \
    --authorized

If TRACE-enabled finding fires, the XST chain works: attacker XSS issues a TRACE request via XHR, the server echoes the request (including HttpOnly cookies that XHR-set-cookies access can't normally read), JavaScript reads the response body, full session theft.

Example 3 — WebDAV legacy audit on a recently-acquired domain

User: "We just acquired example.io — quick method-surface check before we re-point DNS."

python3 ${CLAUDE_PLUGIN_ROOT}/skills/probing-dangerous-http-methods/scripts/probe_methods.py \
    https://example.io \
    --authorized --min-severity medium

Often surfaces decade-old WebDAV / DEBUG defaults that nobody disabled on the previous owner's stack.

Output

JSON / JSONL / Markdown. Exit 0 / 1 / 2 per lib/report.py.

Error Handling

• Method returns 405 → expected behavior, no finding
• Method returns 403 → access-controlled (acceptable), no finding, but INFO note recorded
• Method returns 500 → INFO finding flagging error-handling concern
• Connection error → exit 2

Resources

• references/THEORY.md — Per-method attack semantics
• references/PLAYBOOK.md — How to disable each method per server type
• ../analyzing-tls-config/references/AUTHORIZATION.md — Active-scan authorization