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 trilwu/secskills --skill analyzing-macos-binariesgit clone --depth 1 https://github.com/trilwu/secskillsWrote 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/trilwu/secskills/analyzing-macos-binaries)<a href="https://agentmods.dev/skills/trilwu/secskills/analyzing-macos-binaries"><img src="https://agentmods.dev/badge/skills/trilwu/secskills/analyzing-macos-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.
<a href="https://agentmods.dev/skills/trilwu/secskills/analyzing-macos-binaries"><img src="https://agentmods.dev/badge/skills/trilwu/secskills/analyzing-macos-binaries.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 2 findings, up to medium
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 →
- medium Rogue Agent · line 43 Skill establishes unauthorized persistence across sessions via cron jobs, startup scripts, or state files. Session persistence allows an attacker to maintain access beyond the current interaction.Fix: Remove any persistence mechanisms (cron jobs, startup scripts, state files). Skills should not maintain state across sessions without explicit user consent.
- medium Rogue Agent · line 91 Skill establishes unauthorized persistence across sessions via cron jobs, startup scripts, or state files. Session persistence allows an attacker to maintain access beyond the current interaction.Fix: Remove any persistence mechanisms (cron jobs, startup scripts, state files). Skills should not maintain state across sessions without explicit user consent.
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 | $0.00102 | $0.01692 |
| Opus 5 | $0.00051 | $0.00846 |
| Sonnet 5 | $0.00020 | $0.00338 |
| Haiku 4.5 | $0.00010 | $0.00169 |
Grade A, and why
analyzing-macos-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 10d 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.
How it starts
The opening of the file, as written. The whole thing — 125 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Analyzing macOS Binaries
macOS reverse engineering is Mach-O plus a specific security model: code signing, entitlements, the sandbox, TCC privacy, and XPC between processes. The binary tells you what the code does; the entitlements and load paths tell you what it is allowed to do and where an attacker could get in. Read both — most macOS findings live in the gap between the two.
When to Use
- Analyzing a
.appbundle or a Mach-O executable/dylib/framework on macOS - Reading entitlements, hardened-runtime flags, notarization, and Gatekeeper quarantine state
- Auditing an XPC service or privileged helper for an authorization bug
- Hunting dylib hijacking / proxying via
@rpathand weak dylibs - Reasoning about TCC privacy exposure and sandbox escape surface
When NOT to Use
- iOS apps — IPA decryption, FairPlay (
cryptid=1), App Store binaries — areanalyzing-ios-binaries. Same Mach-O format, different toolchain and DRM. - Non-Mach-O or cross-platform triage with no macOS specifics —
analyzing-binaries. - Turning a memory-corruption crash into an exploit —
exploiting-memory-corruption. - A Mach-O that is packed/encrypted before you can read it —
unpacking-protected-binaries.
Triage the Binary and Bundle
- Thin the universal binary. macOS ships fat binaries (x86_64 + arm64); use
lipo -thin(orlipo -archsto list) so your tools work on one slice. - Read the Mach-O.
otool -lfor load commands,otool -Lfor linked dylibs and their paths,nmfor symbols. Note the load commands that matter later:LC_RPATH,LC_LOAD_DYLIB/LC_LOAD_WEAK_DYLIB, and the code signature. - Walk the bundle.
Contents/MacOS(the binary),Info.plist(identifiers, URL schemes),_CodeSignature, embeddedFrameworks/, and any bundledXPCServices/. The bundle layout is the map of what to analyze.
Recover Objective-C and Swift
- Objective-C keeps rich runtime metadata:
class-dump(ordsdump) reconstructs class, method, and property declarations straight from the binary. This is the fastest way to see the app's structure. - Swift is harder — names are mangled and metadata is less forthcoming. Run
swift-demangleover symbols to get readable names, and expect to lean on the decompiler (Hopper, Ghidra, IDA) more than with Objective-C. - Note which language dominates before choosing the approach; a Swift binary
where
class-dumpreturns little is normal, not a failure.
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.
- 10d ago First seen · 125 lines · 102 tokens per session scan A 797960a9acc2
analyzing-macos-binaries is a skill published in the GitHub repository trilwu/secskills (137 stars, last pushed 5d ago), licensed MIT. It adds 102 tokens to every session and 1,692 once invoked, about $0.0005 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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