code-obfuscation-deobfuscation

code-obfuscation-deobfuscation is a skill for Claude Code, Codex from JustineDevs/premortem. It costs 51 tokens per session (3,525 once invoked), scanned A, a copy of code-obfuscation-deobfuscation, Apache-2.0.

A guide for analysing and reversing code that has been deliberately made difficult to read, especially in compiled programs. It covers techniques such as scrambled control flow, hidden strings, and code that changes itself while running.

In plain words
What is it for?
Use it to identify obfuscation in native binaries and recover their logic using static or runtime analysis.
Why use it?
It helps distinguish ordinary compression from obfuscation and choose an investigation method when normal disassembly is confusing.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/justinedevs/premortem/code-obfuscation-deobfuscation
Any agent
npx skills add JustineDevs/premortem --skill code-obfuscation-deobfuscation
Clone the repo
git clone --depth 1 https://github.com/JustineDevs/premortem

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 code-obfuscation-deobfuscation

README.md
[![agentmods](https://agentmods.dev/badge/skills/justinedevs/premortem/code-obfuscation-deobfuscation.svg)](https://agentmods.dev/skills/justinedevs/premortem/code-obfuscation-deobfuscation)
Your own site
<a href="https://agentmods.dev/skills/justinedevs/premortem/code-obfuscation-deobfuscation"><img src="https://agentmods.dev/badge/skills/justinedevs/premortem/code-obfuscation-deobfuscation.svg" alt="Measured on agentmods" height="20"></a>
Per session 51 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,525 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 100% copy Near-identical to another mod 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 $0.00051 $0.03525
Opus 5 $0.00026 $0.01762
Sonnet 5 $0.00010 $0.00705
Haiku 4.5 $0.00005 $0.00352

Measured 4d ago against content hash ab19c3ed661d, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

code-obfuscation-deobfuscation 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 4d 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

This is a copy

100% identical to code-obfuscation-deobfuscation — 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.

.agents/skills/code-obfuscation-deobfuscation/SKILL.md · 392 lines

How it starts

The opening of the file, as written. The whole thing — 392 lines — stays where its author put it; the contents beside it link to each section on GitHub.

SKILL: Code Obfuscation & Deobfuscation — Expert Analysis Playbook

AI LOAD INSTRUCTION: Expert techniques for identifying, classifying, and defeating code obfuscation in native binaries. Covers junk code, opaque predicates, SMC, control flow flattening, movfuscator, VM protectors (VMProtect/Themida/Code Virtualizer), string encryption, import hiding, and anti-disassembly tricks. Base models often conflate packing with obfuscation and miss the distinction between static and dynamic deobfuscation strategies.

Quick identification picks

Symptom in IDA/Ghidra Likely Obfuscation Start With
Flat CFG, single giant switch Control flow flattening Symbolic execution to recover CFG
Only mov instructions movfuscator demovfuscation / trace-based lifting
pushad/pushfd → VM entry VM protector Handler table extraction
XOR loop before code execution SMC / string encryption Dynamic analysis, breakpoint after decode
Impossible conditions (opaque predicates) Junk code insertion Pattern-based removal
All strings unreadable String encryption Hook decryption routine, or emulate
No imports in IAT Import hiding Trace GetProcAddress / hash resolution

1. JUNK CODE & OPAQUE PREDICATES

1.1 Junk Code Insertion

Dead code that never affects program output, added to increase analysis time.

Identification:

  • Instructions that write to registers/memory never read afterward
  • Function calls whose return values are discarded and have no side effects
  • Loops with invariant bounds that compute unused results

Removal strategy:

  1. Compute def-use chains (IDA/Ghidra data flow analysis)
  2. Mark instructions with no downstream use as dead
  3. Verify removal doesn't change program behavior (trace comparison)

Read the full file on GitHub · 392 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. 4d ago First seen · 392 lines · 51 tokens per session scan A ab19c3ed661d

Subscribe to this mod's changes

code-obfuscation-deobfuscation is a skill published in the GitHub repository JustineDevs/premortem (2 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 51 tokens to every session and 3,525 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 code-obfuscation-deobfuscation, differing in 0 lines, and is treated as a copy.

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