analyzing-binaries

analyzing-binaries is a skill for Claude Code from trilwu/secskills. It costs 68 tokens per session (2,953 once invoked), scanned A, original, MIT.

A guide to examining compiled programs when their original source code is unavailable. It covers executables, firmware, and the native parts of mobile apps.

In plain words
What is it for?
Use it to study executable files, firmware images, and compiled mobile-app components; recover algorithms, file formats, or network protocols; find vulnerabilities; or solve reverse-engineering challenges in CTFs.
Why use it?
It helps narrow a large binary down to the parts that matter, instead of reading all its machine code. This is useful when you need to understand undocumented behavior or recover how something works.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the secskills-core plugin — 30 skills shipped together

Good fit Use it to study executable files, firmware images, and compiled mobile-app components; recover algorithms, file formats, or network protocols; find vulnerabilities; or solve reverse-engineering challenges in CTFs.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/trilwu/secskills/analyzing-binaries
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 trilwu/secskills --skill analyzing-binaries
Clone the repo
git clone --depth 1 https://github.com/trilwu/secskills

Made for: Claude Code.

Or install secskills-core, the plugin that ships this one along with the rest of its 30 skills.

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 analyzing-binaries

README.md
[![agentmods](https://agentmods.dev/badge/skills/trilwu/secskills/analyzing-binaries/github.svg)](https://agentmods.dev/skills/trilwu/secskills/analyzing-binaries)
Your own site
<a href="https://agentmods.dev/skills/trilwu/secskills/analyzing-binaries"><img src="https://agentmods.dev/badge/skills/trilwu/secskills/analyzing-binaries/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 analyzing-binaries

Your own site · 80×15
<a href="https://agentmods.dev/skills/trilwu/secskills/analyzing-binaries"><img src="https://agentmods.dev/badge/skills/trilwu/secskills/analyzing-binaries.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 68 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,953 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. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 1 finding, up to high

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • high Prompt Injection · line 233
    Hidden instructions were detected in comments or invisible text. These could contain malicious directives. Manual review is recommended.
    Fix: Audit all comments and invisible characters. Remove any instructions that direct the agent to perform unauthorized actions. Use plain, reviewable content.
How audits are shown
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 $0.00068 $0.02953
Opus 5 $0.00034 $0.01477
Sonnet 5 $0.00014 $0.00591
Haiku 4.5 $0.00007 $0.00295

Measured 9d ago against content hash 0a84cdf6094a, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

analyzing-binaries 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 9d 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

Copies of this mod

1 near-identical copy found in the catalogue:

secskills-core/skills/analyzing-binaries/SKILL.md · 259 lines

How it starts

The opening of the file, as written. The whole thing — 259 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Analyzing Binaries

Reverse engineering is hypothesis testing against a program you cannot read. The cost of the job is dominated by how much code you look at, so the whole discipline is about narrowing: triage first, find the interesting few percent, then read that carefully.

When to Use

  • Understanding what an unknown or undocumented executable does
  • Recovering an algorithm, file format, or wire protocol from a binary
  • Locating a vulnerability in a closed-source target
  • Firmware analysis for embedded and IoT devices
  • Reversing challenges in CTFs

When NOT to Use

  • Live malware with intent to detonate — use analyzing-malware, which covers containment and safe detonation. Come back here for the disassembly.
  • A raw shellcode blob with no headers (position-independent payload, stager, egg-hunter) — use analyzing-shellcode
  • Source is available — use auditing-code-for-vulnerabilities
  • Android/iOS app assessment as a whole — use testing-mobile-applications; use this skill for the native .so/Mach-O components inside it
  • A framework runtime rather than a plain binary — the toolchain is specific and generic RE will not get there: reversing-flutter-apps for libapp.so/Dart snapshots, reversing-unity-il2cpp for libil2cpp.so plus global-metadata.dat, reversing-react-native-apps for Hermes bytecode
  • A language runtime with its own symbol recoveryanalyzing-go-binaries (pclntab survives stripping), analyzing-rust-binaries (panic strings leak source paths), analyzing-dotnet-assemblies (IL decompiles to C#). Reaching for generic RE on these wastes most of the effort
  • A packed or protected executable — use unpacking-protected-binaries first; there is nothing to disassemble until it is dumped
  • A whole firmware image to extract before any RE — use analyzing-firmware-images for binwalk, filesystem carving, and cross-architecture emulation; return here for an individual binary inside it

Read the full file on GitHub · 259 lines

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. 9d ago First seen · 259 lines · 68 tokens per session scan A 0a84cdf6094a

Subscribe to this mod's changes

analyzing-binaries is a skill published in the GitHub repository trilwu/secskills (137 stars, last pushed 4d ago), licensed MIT. It adds 68 tokens to every session and 2,953 once invoked, about $0.0003 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 2026-08-30.

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