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 skills add JustineDevs/premortem --skill heap-exploitationgit clone --depth 1 https://github.com/JustineDevs/premortemWrote 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/justinedevs/premortem/heap-exploitation)<a href="https://agentmods.dev/skills/justinedevs/premortem/heap-exploitation"><img src="https://agentmods.dev/badge/skills/justinedevs/premortem/heap-exploitation/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.
<a href="https://agentmods.dev/skills/justinedevs/premortem/heap-exploitation"><img src="https://agentmods.dev/badge/skills/justinedevs/premortem/heap-exploitation.svg" alt="Reviewed on agentmods" width="80" 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 | $0.00053 | $0.02527 |
| Opus 5 | $0.00026 | $0.01264 |
| Sonnet 5 | $0.00011 | $0.00505 |
| Haiku 4.5 | $0.00005 | $0.00253 |
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 5d 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
100% identical to heap-exploitation — 0 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 — 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.
0. RELATED ROUTING
- stack-overflow-and-rop — when the overflow is on the stack rather than the heap
- format-string-exploitation — leak heap/libc addresses via format string
- arbitrary-write-to-rce — convert heap arbitrary write into code execution
- binary-protection-bypass — bypass ASLR/RELRO to use heap write effectively
Advanced References
- HOUSE_OF_TECHNIQUES.md — House of Force/Spirit/Orange/Einherjar/Roman/Pig/Banana/Cat/Apple and tcache attacks
- IO_FILE_EXPLOITATION.md — _IO_FILE vtable hijack, FSOP, stdout/stdin abuse, exit flow exploitation
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 |
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.
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.
- 5d ago First seen · 218 lines · 53 tokens per session scan A aa73ba2c7b9f
heap-exploitation is a skill published in the GitHub repository JustineDevs/premortem (2 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 53 tokens to every session and 2,527 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to heap-exploitation, differing in 0 lines, and is treated as a copy.
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