manually-unpacking-a-packed-binary

manually-unpacking-a-packed-binary is a skill for Claude Code, Codex from meltedinhex/analyst-ai-pack. It costs 74 tokens per session (712 once invoked), scanned A, original, Apache-2.0.

A reverse-engineering guide for manually unpacking a Windows binary protected by a custom or unknown packer. It uses a debugger to find the original entry point and save the unpacked program for inspection.

In plain words
What is it for?
Use it to examine packed sections, identify the original entry point, dump the unpacked image, and continue with import reconstruction.
Why use it?
Generic unpackers may fail when the protection is unusual. Manual analysis can reveal the original code needed for later static analysis.

Skill for Claude CodeCodex

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

Good fit Use it to examine packed sections, identify the original entry point, dump the unpacked image, and continue with import reconstruction.

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Install with agentmods
npx agentmods add skills/meltedinhex/analyst-ai-pack/manually-unpacking-a-packed-binary
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 meltedinhex/analyst-ai-pack --skill manually-unpacking-a-packed-binary
Clone the repo
git clone --depth 1 https://github.com/meltedinhex/analyst-ai-pack

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 manually-unpacking-a-packed-binary

README.md
[![agentmods](https://agentmods.dev/badge/skills/meltedinhex/analyst-ai-pack/manually-unpacking-a-packed-binary/github.svg)](https://agentmods.dev/skills/meltedinhex/analyst-ai-pack/manually-unpacking-a-packed-binary)
Your own site
<a href="https://agentmods.dev/skills/meltedinhex/analyst-ai-pack/manually-unpacking-a-packed-binary"><img src="https://agentmods.dev/badge/skills/meltedinhex/analyst-ai-pack/manually-unpacking-a-packed-binary/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 manually-unpacking-a-packed-binary

Your own site · 80×15
<a href="https://agentmods.dev/skills/meltedinhex/analyst-ai-pack/manually-unpacking-a-packed-binary"><img src="https://agentmods.dev/badge/skills/meltedinhex/analyst-ai-pack/manually-unpacking-a-packed-binary.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 74 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 712 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. 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 $0.00074 $0.00712
Opus 5 $0.00037 $0.00356
Sonnet 5 $0.00015 $0.00142
Haiku 4.5 $0.00007 $0.00071

Measured 5d ago against content hash b7063f447a7f, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

manually-unpacking-a-packed-binary 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.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/analyst.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.

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.

skills/manually-unpacking-a-packed-binary/SKILL.md · 91 lines

How it starts

The opening of the file, as written. The whole thing — 91 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Manually Unpacking a Packed Binary

When to Use

  • A sample is runtime-packed by a custom/unknown packer that UPX and generic unpackers cannot handle.
  • You need to locate the original entry point (OEP) and dump the unpacked image for static analysis.

Do not use generic auto-unpackers here — this is the manual path for cases where they fail. Run the sample only inside an isolated, instrumented debugger VM.

Prerequisites

  • A debugger (x64dbg) on an isolated VM and the packed sample.

Safety & Handling

  • The sample executes during unpacking; do this only in a disposable, isolated VM with snapshots.

Workflow

Step 1: Characterize the packer statically

python scripts/analyst.py inspect packed.exe

Reports section entropy, suspicious section names (UPX, .vmp, random), small import tables, and a write-then-execute section (classic unpacker stub).

Step 2: Find candidate OEP heuristics

Set a memory breakpoint on the unpacked code section's execution; the packer's tail jump (a far jmp/ret into a different section) typically transfers control to the OEP.

Step 3: Dump at OEP

When stopped at OEP, dump the process image and proceed to import reconstruction (see the dump-and-rebuild skill).

Step 4: Verify the dump

Confirm the dumped image has a sane entry point, restored imports, and readable code.

Validation

  • The unpacking stub is identified by a write→execute section transition.
  • The tail jump lands in a different section than the stub (OEP candidate).
  • The dumped image disassembles cleanly with recognizable runtime startup code.

Pitfalls

  • Stopping at a stage-2 stub rather than the true OEP in multi-layer packers.
  • Hardware-breakpoint detection by the packer — vary the breakpoint strategy.
  • Dumping before the import table is fully resolved.

References

Read the full file on GitHub · 91 lines

Files

What ships with it

3 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. 5d ago First seen · 91 lines · 74 tokens per session scan A b7063f447a7f

Subscribe to this mod's changes

manually-unpacking-a-packed-binary is a skill published in the GitHub repository meltedinhex/analyst-ai-pack (22 stars, last pushed 2mo ago), licensed Apache-2.0. It adds 74 tokens to every session and 712 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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