heap-exploitation

heap-exploitation is a skill for Claude Code, Codex from miru-zero/zero-brain. It costs 53 tokens per session (2,551 once invoked), scanned A, a copy of heap-exploitation, MIT.

A guide to exploiting memory-management bugs in the heap, the area a program uses for dynamically allocated data. It focuses on ptmalloc2, the heap allocator used by many versions of the GNU C library.

In plain words
What is it for?
Use it to investigate use-after-free, double-free, overflow, and off-by-one bugs, then assess paths to arbitrary memory writes or code execution in authorized security work.
Why use it?
It helps choose exploitation techniques that match the allocator and its version, including protections that make older approaches fail.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/miru-zero/zero-brain/heap-exploitation
Any agent
npx skills add miru-zero/zero-brain --skill heap-exploitation
Clone the repo
git clone --depth 1 https://github.com/miru-zero/zero-brain

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 heap-exploitation

README.md
[![agentmods](https://agentmods.dev/badge/skills/miru-zero/zero-brain/heap-exploitation.svg)](https://agentmods.dev/skills/miru-zero/zero-brain/heap-exploitation)
Your own site
<a href="https://agentmods.dev/skills/miru-zero/zero-brain/heap-exploitation"><img src="https://agentmods.dev/badge/skills/miru-zero/zero-brain/heap-exploitation.svg" alt="Measured on agentmods" height="20"></a>
Per session 53 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,551 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 98% copy Near-identical to another mod 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 $0.00053 $0.02551
Opus 5 $0.00026 $0.01275
Sonnet 5 $0.00011 $0.00510
Haiku 4.5 $0.00005 $0.00255

Measured 3d ago against content hash d49164c73bfa, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

heap-exploitation 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 3d 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.

Origin

This is a copy

98% identical to heap-exploitation — 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.

skills/heap-exploitation/SKILL.md · 218 lines

How it starts

The opening of the file, as written. The whole thing — 218 lines — stays where its author put it; the contents beside it link to each section on GitHub.

SKILL: Heap Exploitation — Expert Attack Playbook

AI LOAD INSTRUCTION: Expert glibc heap exploitation techniques. Covers ptmalloc2 internals, bin structures, tcache mechanics, libc/heap leak methods, and attack selection by glibc version. Distilled from ctf-wiki heap sections, how2heap, and real-world exploitation. Base models often confuse glibc version constraints and miss safe-linking (PROTECT_PTR) introduced in 2.32.

Advanced References


1. PTMALLOC2 STRUCTURE QUICK REFERENCE

malloc_chunk Layout (64-bit)

         chunk pointer (returned by malloc - 0x10)
         ┌──────────────────────────┐
    0x00 │  prev_size (if prev free)│
    0x08 │  size        | A | M | P │  ← P=PREV_INUSE, M=IS_MMAPPED, A=NON_MAIN_ARENA
         ├──────────────────────────┤  ← user data starts here (returned pointer)
    0x10 │  fd (if free)            │  ← forward pointer to next free chunk
    0x18 │  bk (if free)            │  ← backward pointer to prev free chunk
    0x20 │  fd_nextsize (large only)│
    0x28 │  bk_nextsize (large only)│
         └──────────────────────────┘

Bin Types

Bin Size Range (64-bit) Structure LIFO/FIFO
tcache (per-thread) ≤ 0x410 (7 entries per size) Singly linked (next pointer) LIFO
fastbin ≤ 0x80 (default) Singly linked (fd) LIFO
unsortedbin Any freed size Doubly linked circular FIFO
smallbin < 0x400 Doubly linked circular FIFO
largebin ≥ 0x400 Doubly linked + size-sorted Sorted

Read the full file on GitHub · 218 lines

Files

What ships with it

2 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.

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. 3d ago First seen · 218 lines · 53 tokens per session scan A d49164c73bfa

Subscribe to this mod's changes

heap-exploitation is a skill published in the GitHub repository miru-zero/zero-brain (0 stars, last pushed 16d ago), licensed MIT. It adds 53 tokens to every session and 2,551 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. It is 98% identical to heap-exploitation, differing in 4 lines, and is treated as a copy.

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