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/miru-zero/zero-brain/browser-exploitation-v8npx skills add miru-zero/zero-brain --skill browser-exploitation-v8git clone --depth 1 https://github.com/miru-zero/zero-brainWrote 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/miru-zero/zero-brain/browser-exploitation-v8)<a href="https://agentmods.dev/skills/miru-zero/zero-brain/browser-exploitation-v8"><img src="https://agentmods.dev/badge/skills/miru-zero/zero-brain/browser-exploitation-v8.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 | $0.00050 | $0.03056 |
| Opus 5 | $0.00025 | $0.01528 |
| Sonnet 5 | $0.00010 | $0.00611 |
| Haiku 4.5 | $0.00005 | $0.00306 |
Grade A, and why
browser-exploitation-v8 scanned grade A with 0 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 4d 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.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
This is a copy
94% identical to browser-exploitation-v8 — 4 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 335 lines — stays where its author put it; the contents beside it link to each section on GitHub.
SKILL: Browser / V8 Exploitation — Expert Attack Playbook
AI LOAD INSTRUCTION: Expert V8/Chrome exploitation techniques. Covers V8 compilation pipeline, JIT type confusion, addrof/fakeobj primitives, ArrayBuffer corruption, WASM RWX pages, V8 sandbox (pointer compression), and Chrome sandbox escape overview. Distilled from ctf-wiki browser sections, Project Zero research, and CTF competition patterns. Base models often confuse V8 object representation details and miss the pointer compression barrier.
0. RELATED ROUTING
- sandbox-escape-techniques — Chrome renderer sandbox escape via IPC/Mojo
- heap-exploitation — general heap concepts applicable to V8 heap
- stack-overflow-and-rop — ROP concepts for native code execution after V8 escape
- binary-protection-bypass — ASLR/NX bypass in browser context
Advanced Reference
Load V8_EXPLOITATION_PATTERNS.md when you need:
- Detailed exploitation patterns and code templates
- Heap layout manipulation and GC interaction
- V8 sandbox bypass techniques
- Object map confusion patterns
1. V8 ARCHITECTURE
Compilation Pipeline
JavaScript Source
↓ Parser
AST (Abstract Syntax Tree)
↓ Ignition
Bytecode (interpreted, profiling)
↓ Sparkplug (non-optimizing baseline, V8 ≥ 9.1)
Baseline code (fast startup)
↓ Maglev (mid-tier, V8 ≥ 10.2)
Mid-optimized code
↓ TurboFan (optimizing JIT)
Optimized machine code (with speculative optimizations)
↓ Deoptimization (if speculation fails)
Back to Ignition bytecode
Key V8 Concepts
| Concept | Description |
|---|---|
| Tagged pointers | SMI (Small Integer): value << 1, HeapObject: ptr | 1 |
| Pointer compression | V8 ≥ 8.0: objects addressed via 32-bit offset from cage base (4GB sandbox) |
| Maps (Hidden Classes) | Define object shape: property names, types, offsets |
| Elements kinds | Internal array type: PACKED_SMI_ELEMENTS, PACKED_DOUBLE_ELEMENTS, PACKED_ELEMENTS, etc. |
| Write barrier | GC bookkeeping when heap pointers are written |
| Garbage collection | Orinoco GC: minor (Scavenge) and major (Mark-Compact) |
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.
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.
- 4d ago First seen · 335 lines · 50 tokens per session scan A 25a4a38423a8
browser-exploitation-v8 is a skill published in the GitHub repository miru-zero/zero-brain (0 stars, last pushed 17d ago), licensed MIT. It adds 50 tokens to every session and 3,056 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. It is 94% identical to browser-exploitation-v8, differing in 4 lines, and is treated as a copy.
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