defeating-control-flow-flattening

defeating-control-flow-flattening is a skill for Claude Code, Codex from meltedinhex/analyst-ai-pack. It costs 74 tokens per session (666 once invoked), scanned A, original, Apache-2.0.

A static reverse-engineering method for undoing control-flow flattening, an obfuscation technique that hides a function's original order behind a dispatcher and state variable.

In plain words
What is it for?
Use it with exported disassembly or control-flow graph data from tools such as Ghidra, IDA, or Binary Ninja to detect the pattern, recover transitions, and verify the reconstructed graph.
Why use it?
Flattened code is difficult to read because many blocks appear to jump through one central loop. This method reconstructs the likely original paths without running the program.

Skill for Claude CodeCodex

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

Good fit Use it with exported disassembly or control-flow graph data from tools such as Ghidra, IDA, or Binary Ninja to detect the pattern, recover transitions, and verify the reconstructed graph.

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Install with agentmods
npx agentmods add skills/meltedinhex/analyst-ai-pack/defeating-control-flow-flattening
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 defeating-control-flow-flattening
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 defeating-control-flow-flattening

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

Your own site · 80×15
<a href="https://agentmods.dev/skills/meltedinhex/analyst-ai-pack/defeating-control-flow-flattening"><img src="https://agentmods.dev/badge/skills/meltedinhex/analyst-ai-pack/defeating-control-flow-flattening.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 666 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 $0.00666
Opus 5 $0.00037 $0.00333
Sonnet 5 $0.00015 $0.00133
Haiku 4.5 $0.00007 $0.00067

Measured 11d ago against content hash 96104a7bfe1d, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

defeating-control-flow-flattening 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 11d 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/defeating-control-flow-flattening/SKILL.md · 86 lines

What it actually says

Defeating Control-Flow Flattening

When to Use

  • A function is flattened (a dispatcher loop switching on a state variable, with original blocks as switch cases) and you need to recover the original control flow.
  • You are reversing OLLVM-style or similar flattening.

Do not use this on non-flattened code — confirm the dispatcher/state-variable pattern first. This skill analyzes disassembly/CFG data statically and executes nothing.

Prerequisites

  • A disassembled function's basic-block/edge data (e.g., exported from Ghidra/IDA/Binary Ninja as JSON).

Workflow

Step 1: Detect the flattening structure

python scripts/analyst.py detect cfg.json

Identifies a dispatcher block (high in-degree, switch/compare on a state variable) and the relay/ case blocks that all branch back to it.

Step 2: Recover state transitions

Track the constant assigned to the state variable in each case to determine the successor block, rebuilding the true edges.

Step 3: Reconstruct the original CFG

Emit the deflattened successor mapping (case → next case) for re-annotation in the disassembler.

Step 4: Verify

Confirm the recovered flow has a single entry, sane successors, and no orphan blocks.

Validation

  • The dispatcher is identified by in-degree and state-variable comparison.
  • Each case's next-state constant maps to a real successor block.
  • The reconstructed CFG covers all original (non-relay) blocks.

Pitfalls

  • State variable computed (not a constant) — requires emulation/symbolic execution.
  • Multiple dispatchers or nested flattening.
  • Opaque predicates and bogus blocks inflating the case set.

References

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. 11d ago First seen · 86 lines · 74 tokens per session scan A 96104a7bfe1d

Subscribe to this mod's changes

defeating-control-flow-flattening 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 666 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 2026-08-30.

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