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.
npx agentmods add skills/forefy/.context/webapp-probenpx skills add forefy/.context --skill webapp-probegit clone --depth 1 https://github.com/forefy/.contextWrote 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.
[](https://agentmods.dev/skills/forefy/.context/webapp-probe)<a href="https://agentmods.dev/skills/forefy/.context/webapp-probe"><img src="https://agentmods.dev/badge/skills/forefy/.context/webapp-probe.svg" alt="Measured on agentmods" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00043 | $0.06213 |
| Opus 5 | $0.00022 | $0.03106 |
| Sonnet 5 | $0.00009 | $0.01243 |
| Haiku 4.5 | $0.00004 | $0.00621 |
Grade C, and why
webapp-probe scanned grade C with 2 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 6d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Downloads and executes remote codehighSupply chain
curl | sh runs whatever the server returns today, which is not necessarily what it returned when this was reviewed.
curl -s "https://TARGET/${s}.map" | python3 -c 'import sys,json; Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
import sys,urllib.parse as u How it starts
The opening of the file, as written. The whole thing — 294 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Contents
- Scope & authorization (blast-radius labels)
- Passive analysis of captured traffic:
- Missing or weak security headers
- Insecure session cookies
- Hardcoded secrets & API tokens in bodies
- Improper error handling (stack traces, DB errors, debug pages)
- Outdated / dev-mode technology fingerprints
- RCE-prone parameters in captured requests
- Active probing of the live target: 7. Disclosure-path brute (.git/config/logs, CVE paths) 8. Outdated / vulnerable software port probe 9. Wayback forgotten-endpoint mining + re-probe 10. Dependency confusion (sourcemaps -> npm)
- Runnable snippets
- Output
- Reference files:
references/secret-regexes.md,references/error-signatures.md,references/directory-signatures.md
Scope & authorization
Only run against a web application the user owns or is contractually engaged to test. This skill has two halves, each labelled by blast radius:
- Passive (classes 1-6) - inspects responses and requests you already captured (proxy history, an authenticated crawl, a saved sitemap, files on disk). Sends no new HTTP requests, mutates nothing, and is safe against a frozen capture.
- Active (checks 7-10) - sends live requests to the target and, for Wayback (9) and dependency confirmation (10), to third-party services (the Internet Archive, the npm registry). Check 8 is aggressive (multi-port sweep). Run these only in scope, and prefer a low-traffic window.
Take inputs as whatever you already hold: captured responses/requests for the passive half, and the target's domains / domain:port pairs for the active half. Report a finding exactly where each section says "Report a finding when...".
Passive analysis of captured traffic
Each class is one pass over the capture; each yields per-target findings.
1. Missing or weak security headers
For every captured response, case-insensitively collect the response header names and report each of the ten headers below that is absent. Report a finding when: a response is missing any of these. Remediation is "add the <Header> in responses returning from the server".
What ships with it
3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 6d ago First seen · 294 lines · 43 tokens per session scan C 193d71edbe1f
webapp-probe is a skill published in the GitHub repository forefy/.context (144 stars, last pushed yesterday), licensed MIT. It adds 43 tokens to every session and 6,213 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it C with 2 findings (downloads and executes remote code, 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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