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 agentmods add skills/ogrodev/fsociety/binary-diffingnpx skills add ogrodev/fsociety --skill binary-diffinggit clone --depth 1 https://github.com/ogrodev/fsocietyWhat 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 | $0.00293 | $0.02578 |
| Opus 5 | $0.00147 | $0.01289 |
| Sonnet 5 | $0.00059 | $0.00516 |
| Haiku 4.5 | $0.00029 | $0.00258 |
Grade A, and why
binary-diffing 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 2d 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 — 216 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Binary Diffing
Overview
Binary diffing compares two versions of a compiled binary to isolate exactly what changed. This is one of the highest-value reverse engineering techniques because it converts a vendor's patch into a roadmap pointing straight at the vulnerability. The same technique applies to tracking malware evolution, understanding firmware updates, and auditing software changes between releases.
Why this matters: When Microsoft ships a Patch Tuesday update, the patch itself tells you what was vulnerable. A well-executed diff workflow can identify the exploitable condition in hours, not days.
Core Use Cases
| Use Case | Input | Output |
|---|---|---|
| Patch analysis (1-day development) | Pre-patch + post-patch binary | Vulnerable function, root cause, exploitable condition |
| CVE reproduction | Advisory + patched binary pair | Proof of concept targeting the patched flaw |
| Malware variant tracking | Sample A + Sample B | Behavioral delta, new capabilities, C2 changes |
| Firmware update analysis | Firmware v1 + v2 (extracted) | Changed drivers, new mitigations, removed features |
| Software audit | Release N + Release N+1 | Security-relevant changes, regression candidates |
Tool Routing
| Task | Tool | When to Use |
|---|---|---|
| Byte-level diff | radiff2 <old> <new> |
Quick triage — see raw byte changes |
| Code block comparison | radiff2 -C <old> <new> |
Identify changed basic blocks |
| Graph-based diffing | BinDiff (via Ghidra/IDA export) | Deep function matching with CFG comparison |
| Scriptable diffing | Diaphora (Ghidra/IDA plugin) | Customizable matching, SQL-backed results |
| Similarity scoring | ssdeep -l <old> <new> |
Quick similarity percentage between files |
| Section comparison | r2 -qc 'iS' <old> vs <new> |
Detect section size/permission changes |
| Import/export delta | r2 -qc 'ii' / r2 -qc 'iE' |
New APIs, removed functions |
| String delta | strings or floss on both |
New URLs, error messages, config values |
| Function listing | r2 -qc 'aaa; afl' on both |
Function count, name, and size comparison |
What ships with it
4 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.
- 2d ago First seen · 216 lines · 293 tokens per session scan A fdaf2273b0ac
binary-diffing is a skill published in the GitHub repository ogrodev/fsociety (20 stars, last pushed 5mo ago), licensed MIT. It adds 293 tokens to every session and 2,578 once invoked, about $0.0015 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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