ctf-reverse

ctf-reverse is a skill for Claude Code, Codex from dailyyarn/CTF-agent. It costs 136 tokens per session (6,748 once invoked), scanned A, original, MIT.

A reference guide for reverse engineering, the process of understanding programs from their compiled or obfuscated form. It focuses on capture-the-flag challenges, including binaries, mobile apps, virtual machines, and anti-debugging techniques.

In plain words
What is it for?
Use it to inspect binaries, APKs, WebAssembly, .NET, Go or Rust executables, custom virtual machines, obfuscated code, and anti-analysis protections.
Why use it?
It gives you methods and tool references when source code is unavailable or deliberately difficult to analyze.

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/dailyyarn/ctf-agent/ctf-reverse
Any agent
npx skills add dailyyarn/CTF-agent --skill ctf-reverse
Clone the repo
git clone --depth 1 https://github.com/dailyyarn/CTF-agent

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 ctf-reverse

README.md
[![agentmods](https://agentmods.dev/badge/skills/dailyyarn/ctf-agent/ctf-reverse.svg)](https://agentmods.dev/skills/dailyyarn/ctf-agent/ctf-reverse)
Your own site
<a href="https://agentmods.dev/skills/dailyyarn/ctf-agent/ctf-reverse"><img src="https://agentmods.dev/badge/skills/dailyyarn/ctf-agent/ctf-reverse.svg" alt="Measured on agentmods" height="20"></a>
Per session 136 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 6,748 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00136 $0.06748
Opus 5 $0.00068 $0.03374
Sonnet 5 $0.00027 $0.01350
Haiku 4.5 $0.00014 $0.00675

Measured 4d ago against content hash 9eb28a983722, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

ctf-reverse 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.

ctf_agent/knowledge/embedded_ctf_skills/ctf-reverse/SKILL.md · 402 lines

How it starts

The opening of the file, as written. The whole thing — 402 lines — stays where its author put it; the contents beside it link to each section on GitHub.

CTF Reverse Engineering

Quick reference for RE challenges. For detailed techniques, see supporting files.

Additional Resources

  • tools.md - Static analysis tools (GDB, Ghidra, radare2, IDA, Binary Ninja, dogbolt.org, RISC-V with Capstone, Unicorn emulation, Python bytecode, WASM, Android APK, .NET, packed binaries)
  • tools-dynamic.md (includes Intel Pin instruction-counting side channel for movfuscated binaries) - Dynamic analysis tools: Frida (hooking, anti-debug bypass, memory scanning, Android/iOS), angr symbolic execution (path exploration, constraints, CFG), lldb (macOS/LLVM debugger), x64dbg (Windows), Qiling (cross-platform emulation with OS support), Triton (dynamic symbolic execution)
  • tools-advanced.md - Advanced tools: VMProtect/Themida analysis, binary diffing (BinDiff, Diaphora), deobfuscation frameworks (D-810, GOOMBA, Miasm), Rizin/Cutter, RetDec, advanced GDB (Python scripting, conditional breakpoints, watchpoints, reverse debugging with rr, pwndbg/GEF), advanced Ghidra scripting, patching (Binary Ninja API, LIEF)
  • anti-analysis.md - Comprehensive anti-analysis: Linux anti-debug (ptrace, /proc, timing, signals, direct syscalls), Windows anti-debug (PEB, NtQueryInformationProcess, heap flags, TLS callbacks, HW/SW breakpoint detection, exception-based, thread hiding), anti-VM/sandbox (CPUID, MAC, timing, artifacts, resources), anti-DBI (Frida detection/bypass), code integrity/self-hashing, anti-disassembly (opaque predicates, junk bytes), MBA identification/simplification, bypass strategies
  • patterns.md - Foundational binary patterns: custom VMs, anti-debugging, nanomites, self-modifying code, XOR ciphers, mixed-mode stagers, LLVM obfuscation, S-box/keystream, SECCOMP/BPF, exception handlers, memory dumps, byte-wise transforms, x86-64 gotchas, signal-based exploration, malware anti-analysis, multi-stage shellcode, timing side-channel, multi-thread anti-debug with decoy + signal handler MBA
  • patterns-ctf.md - Competition-specific patterns (Part 1): hidden emulator opcodes, LD_PRELOAD key extraction, SPN static extraction, image XOR smoothness, byte-at-a-time cipher, mathematical convergence bitmap, Windows PE XOR bitmap OCR, two-stage RC4+VM loaders, GBA ROM meet-in-the-middle, Sprague-Grundy game theory, kernel module maze solving, multi-threaded VM channels, backdoored shared library detection via string diffing
  • patterns-ctf-2.md - Competition-specific patterns (Part 2): multi-layer self-decrypting brute-force, embedded ZIP+XOR license, stack string deobfuscation, prefix hash brute-force, CVP/LLL lattice for integer validation, decision tree function obfuscation, GLSL shader VM, GF(2^8) Gaussian elimination, Z3 single-line Python circuit, sliding window popcount, keyboard LED Morse code via ioctl
  • languages.md - Language/platform-specific: Python bytecode & opcode remapping, Python version-specific bytecode, Pyarmor static unpack, DOS stubs, Unity IL2CPP, HarmonyOS HAP/ABC, Brainfuck/esolangs, UEFI, transpilation to C, code coverage side-channel, OPAL functional reversing, non-bijective substitution, Roblox place file analysis, Godot game asset extraction, Rust serde_json schema recovery, Verilog/hardware RE, Android JNI RegisterNatives, Ruby/Perl polyglot, Electron ASAR extraction + native binary analysis, Node.js npm runtime introspection
  • languages-compiled.md - Go binary reversing (GoReSym, goroutines, memory layout, channel ops, embed.FS), Rust binary reversing (demangling, Option/Result, Vec, panic strings), Swift binary reversing (demangling, protocol witness tables), Kotlin/JVM (coroutine state machines), C++ (vtable reconstruction, RTTI, STL patterns)
  • platforms.md - Platform-specific RE: macOS/iOS (Mach-O, code signing, Objective-C runtime, Swift, dyld, jailbreak bypass), embedded/IoT firmware (binwalk, UART/JTAG/SPI extraction, ARM/MIPS, RTOS), kernel drivers (Linux .ko, eBPF, Windows .sys), game engines (Unreal Engine, Unity, anti-cheat, Lua), automotive CAN bus, RISC-V advanced

Read the full file on GitHub · 402 lines

Files

What ships with it

10 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. 4d ago First seen · 402 lines · 136 tokens per session scan A 9eb28a983722

Subscribe to this mod's changes

ctf-reverse is a skill published in the GitHub repository dailyyarn/CTF-agent (5 stars, last pushed 5mo ago), licensed MIT. It adds 136 tokens to every session and 6,748 once invoked, about $0.0007 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 2026-08-31.

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