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.