---
name: ssrf-detector
description: "SSRF detector: finds every outbound HTTP call (fetch, axios, got, http, requests, HttpClient, Invoke-RestMethod) where the URL is user-controlled (req.body/req.query/req.params) and grades URL-pre-fetch validation (URL-parse, hostname allowlist, metadata-IP blocking). LLM per-URL-flow classifies user-control, pre-validation quality, and metadata-service exploitation risk (169.254.169.254). Read-only. Audience: Senior. Trigger: /ssrf-detector"
trigger: /ssrf-detector
---

## What this is for

Every `fetch(url)` where `url` comes from `req.query.url` is an SSRF
opportunity. Attackers route through the server to scan internal networks
or hit the cloud metadata service (169.254.169.254) for IAM credentials.
Existing scanners flag "no URL validation" generically - this skill
inventories each sink, traces whether the URL is user-controlled, and
grades each validation layer present (scheme, hostname, metadata-IP
blocking, DNS resolution check).


## PROTECTION RULE - never ~/.claude/

Read-only skill. Guard required if write mode added later.

## ## What You Must Do When Invoked
During analysis, assign a confidence level to each finding: proven (confirmed by evidence), likely (strong signal, needs review), or suspected (weak signal).

### Step 1

1. If `-help` is passed, print the `## Usage` block below and stop.

### Step 2

2. Confirm `-ProjectDir` is provided and the path exists.

### Step 3

3. Run: `scripts/ssrf-scan.ps1 -ProjectDir "<path>"`

### Step 4

4. LLM reads the JSON output. For each URL-flow finding:

### Step 5

- **User-controlled?** Does the URL descend from `req.body.*`,

### Step 6

`req.query.*`, `req.params.*`, `event.body.*`, `context.args.*`?

### Step 7

- **Pre-validated?** Is the URL parsed (`new URL(url)`), scheme-checked

### Step 8

(`startsWith('https://')`), hostname-allowlisted (`allowlist.includes`),

### Step 9

metadata-IP blocked (`169.254` / `127.0.0.1` / `localhost` checked)?

### Step 10

Collect which `validationTypes[]` are present.

### Step 11

- **Metadata-service risk:** If the attacker controls the URL, can they

### Step 12

point it at `http://169.254.169.254/latest/meta-data/` to steal cloud

### Step 13

provider IAM credentials? No metadata-IP block = high risk.

### Step 14

5. Write `ssrf-detector-report.md` to the working directory.

## Usage

```
/ssrf-detector                          # interactive
/ssrf-detector <dir>                    # scan project
/ssrf-detector -help                    # show usage
```

Returns JSON with `findings[]`:
`{file, line, sinkType, hasUserControl, hasValidation, validationTypes[], code}` plus summary counts.