ssrf-oob

ssrf-oob is a skill for Claude Code, Codex from forefy/.context. It costs 37 tokens per session (2,673 once invoked), scanned A, original, MIT.

A security-testing guide for finding blind SSRF, a server-side request forgery where a server is tricked into making a request you cannot see in its response. It uses an out-of-band listener that records callback requests.

In plain words
What is it for?
Use it to test URL parameters and headers, forward selected headers, and watch for DNS or HTTP callbacks from the target.
Why use it?
It helps confirm SSRF when the target response gives no visible evidence. It also keeps testing limited to systems you own or are authorized to assess.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to test URL parameters and headers, forward selected headers, and watch for DNS or HTTP callbacks from the target.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/forefy/.context/ssrf-oob
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add forefy/.context --skill ssrf-oob
Clone the repo
git clone --depth 1 https://github.com/forefy/.context

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for ssrf-oob

README.md
[![agentmods](https://agentmods.dev/badge/skills/forefy/.context/ssrf-oob/github.svg)](https://agentmods.dev/skills/forefy/.context/ssrf-oob)
Your own site
<a href="https://agentmods.dev/skills/forefy/.context/ssrf-oob"><img src="https://agentmods.dev/badge/skills/forefy/.context/ssrf-oob/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for ssrf-oob

Your own site · 80×15
<a href="https://agentmods.dev/skills/forefy/.context/ssrf-oob"><img src="https://agentmods.dev/badge/skills/forefy/.context/ssrf-oob.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 37 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,673 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00037 $0.02673
Opus 5 $0.00018 $0.01337
Sonnet 5 $0.00007 $0.00535
Haiku 4.5 $0.00004 $0.00267

Measured 5d ago against content hash 71a764d91cd8, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

ssrf-oob scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 5d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

import urllib.parse, urllib.request, ssl
skills/applicative-pentest/ssrf-oob/SKILL.md · 144 lines

How it starts

The opening of the file, as written. The whole thing — 144 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Contents

  • Scope & authorization
  • Step 0 - stand up the collaborator / OAST listener
  • Injection points (query params, headers, bulk sweep)
  • Port -> scheme logic
  • Methodology
  • Runnable snippets
  • Output

Scope & authorization

Only run against hosts you own or are contractually engaged to test. This check is active and aggressive: it sends live HTTP requests that try to coerce the target into making outbound DNS/HTTP requests to infrastructure you control. Do not point it at third parties.

The whole method is out-of-band: the target's HTTP response usually will not tell you whether SSRF fired. The signal is the interaction (a DNS resolution and/or an HTTP hit) arriving at your callback host. So the OAST listener is the instrument - stand it up first and keep watching it throughout.

Step 0 - stand up the collaborator / OAST listener

You need a host that logs inbound DNS and HTTP and that you can attribute hits back to. Any of these works; they are interchangeable for this method:

  • Interactsh (interactsh-client) - self-hostable, gives you a unique callback domain and a live feed of DNS/HTTP/SMTP hits.
  • Burp Collaborator - "Copy to clipboard" a payload domain; poll for interactions.
  • Your own authoritative DNS + web log - a domain whose NS you control; tail the query log and a listener on 80/443.

Call this callback host OAST_HOST below. The core trick: encode who fired the callback into the hostname itself by prefixing a unique label, e.g. dest.OAST_HOST, xforwardedfor.OAST_HOST, or t3-url.OAST_HOST. Because every injection point uses a distinct subdomain label, a single lookup in your OAST feed tells you exactly which param/header on which target reached out - even though the HTTP response was silent.

Injection points

A server-side fetch can be triggered from three places an app commonly trusts. Test all three.

A. Query params - parameters whose value the app treats as a URL/host/path to fetch, follow, or render. Wordlist (24, carry verbatim):

Read the full file on GitHub · 144 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 5d ago Changed · +1 lines 71a764d91cd8
  2. 9d ago First seen · 143 lines · 37 tokens per session scan A 963475607086

Subscribe to this mod's changes

ssrf-oob is a skill published in the GitHub repository forefy/.context (144 stars, last pushed 2d ago), licensed MIT. It adds 37 tokens to every session and 2,673 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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