ctf-skills is a collection of agent instructions for solving capture-the-flag security challenges, including web exploitation, binary vulnerabilities, cryptography, reverse engineering, forensics, and OSINT. It is intended for agents and people working through CTF problems, and its skills can be loaded into supported coding-agent workflows.
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 ljagiello/ctf-skills --skill ctf-reversegit clone --depth 1 https://github.com/ljagiello/ctf-skillsWrote 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/ljagiello/ctf-skills/ctf-reverse)<a href="https://agentmods.dev/skills/ljagiello/ctf-skills/ctf-reverse"><img src="https://agentmods.dev/badge/skills/ljagiello/ctf-skills/ctf-reverse/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/ljagiello/ctf-skills/ctf-reverse"><img src="https://agentmods.dev/badge/skills/ljagiello/ctf-skills/ctf-reverse.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- Socket warn
- Snyk warn
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 | $0.00125 | $0.03181 |
| Opus 5 | $0.00063 | $0.01590 |
| Sonnet 5 | $0.00025 | $0.00636 |
| Haiku 4.5 | $0.00013 | $0.00318 |
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 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.
This is a copy
84% identical to reverse-engineering — 95 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.
How it starts
The opening of the file, as written. The whole thing — 168 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.
Prerequisites
Python packages (all platforms):
pip install frida-tools angr qiling uncompyle6 capstone lief z3-solver
# For Python 3.9+ bytecode: build pycdc from source
git clone https://github.com/zrax/pycdc && cd pycdc && cmake . && make
Linux (apt):
apt install gdb radare2 binutils strace ltrace apktool upx
macOS (Homebrew):
brew install gdb radare2 binutils apktool upx ghidra
radare2 plugins:
r2pm -ci r2ghidra # Native Ghidra decompiler for radare2
Manual install:
- pwndbg — Linux: GitHub, macOS:
brew install pwndbg/tap/pwndbg-gdb
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 - 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)
- tools-emulation.md - Emulation frameworks and side-channel tooling: Qiling (cross-platform OS-level emulation), Triton (DSE), Intel Pin instruction-counting + genetic algorithm side channel, opcode-only trace reconstruction, LD_PRELOAD time freeze and memcmp side-channel for byte-by-byte bruteforce
- tools-advanced.md - Advanced tools (Part 1): VMProtect/Themida analysis, binary diffing (BinDiff, Diaphora), deobfuscation frameworks (D-810, GOOMBA, Miasm), Qiling framework, Triton DSE, Manticore, Rizin/Cutter, RetDec, custom VM bytecode lifting to LLVM IR
- tools-advanced-2.md - Advanced tools (Part 2): advanced GDB (Python scripting, brute-force, conditional breakpoints, watchpoints, reverse debugging with rr, pwndbg/GEF), advanced Ghidra scripting, patching (Binary Ninja API, LIEF), GDB constraint extraction + ILP solver (BackdoorCTF 2017), GDB position-encoded input zero flag monitoring (EKOPARTY 2017), LD_PRELOAD execute-only binary dump (BackdoorCTF 2017), PEDA current_inst bit-by-bit flag scraper (CONFidence CTF 2019 Teaser)
- anti-analysis.md - Anti-analysis taxonomy: 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, comprehensive bypass strategies
- anti-analysis-ctf.md - CTF writeup techniques: SIGILL handler for execution mode switching (Hack.lu 2015), SIGFPE signal handler side-channel via strace counting (PlaidCTF 2017), instruction trace inversion with Keystone and Unicorn (MeePwn 2017), call-less function chaining via stack frame manipulation (THC 2018), parent-patched child binary dump via
process_vm_writev(Google CTF Quals 2018) - 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, custom mangle reversing, position-based transforms, hex-encoded string comparison, signal-based binary exploration
- patterns-runtime.md - Runtime patching and oracle techniques: malware anti-analysis bypass, multi-stage shellcode loaders, timing side-channel attacks, multi-thread anti-debug with decoy + signal handler MBA (ApoorvCTF 2026), INT3 patch + coredump brute-force oracle (Pwn2Win 2016), signal handler chain + LD_PRELOAD oracle (Nuit du Hack 2016), printf format string VM decompilation to Z3 (SECCON 2017), quadtree recursive image format parser (Google CTF Quals 2018)
- 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, custom binfmt kernel module with RC4 flat binaries, hash-resolved imports / no-import ransomware, ELF section header corruption for anti-analysis
- 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, GF(2^8) Gaussian elimination, ROP chain obfuscation analysis (ROPfuscation)
- patterns-ctf-3.md - Competition-specific patterns (Part 3): Z3 single-line Python circuit, sliding window popcount, keyboard LED Morse code via ioctl, C++ destructor-hidden validation, syscall side-effect memory corruption, MFC dialog event handlers, VM sequential key-chain brute-force, Burrows-Wheeler transform inversion, OpenType font ligature exploitation, GLSL shader VM with self-modifying code, instruction counter as cryptographic state, batch crackme automation via objdump, fork+pipe+dead branch anti-analysis, TensorFlow DNN inversion via sigmoid layer inversion, BPF filter analysis via kernel JIT to x64 assembly
- languages.md - Language-specific: Python bytecode & opcode remapping, Python version-specific bytecode, Pyarmor static unpack, DOS stubs, Unity IL2CPP, HarmonyOS HAP/ABC, Brainfuck/esolangs (+ BF character-by-character static analysis, BF side-channel read count oracle, BF comparison idiom detection), UEFI, transpilation to C, code coverage side-channel, OPAL functional reversing, non-bijective substitution, FRACTRAN program inversion
- languages-platforms.md - Platform/framework-specific: Roblox place file analysis, Godot game asset extraction, Rust serde_json schema recovery, Android JNI RegisterNatives obfuscation, Android DEX runtime bytecode patching via /proc/self/maps, Android native .so loading bypass via new project, Frida Firebase Cloud Functions bypass, Verilog/hardware RE, prefix-by-prefix hash reversal, Ruby/Perl polyglot constraint satisfaction, 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, Go binary UUID patching for C2 enumeration), Rust binary reversing (demangling, Option/Result, Vec, panic strings), Swift binary reversing (demangling, protocol witness tables), Kotlin/JVM (coroutine state machines), Haskell GHC CMM intermediate language for recursive structure analysis, 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
- platforms-hardware.md - Hardware and advanced architecture RE: HD44780 LCD controller GPIO reconstruction, RISC-V advanced (custom extensions, privileged modes, debugging), ARM64/AArch64 reversing and exploitation (calling convention, ROP gadgets, qemu-aarch64-static emulation)
- field-notes.md - Quick reference notes: binary types, anti-debugging bypass, specialized patterns, CTF case notes
What ships with it
18 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.
- anti-analysis-ctf.md 11 KB
- anti-analysis.md 23 KB
- field-notes.md 32 KB
- languages-compiled.md 27 KB
- languages-platforms.md 28 KB
- languages.md 23 KB
- patterns-ctf-2.md 19 KB
- patterns-ctf-3.md 38 KB
- patterns-ctf.md 30 KB
- patterns-runtime.md 12 KB
- patterns.md 20 KB
- platforms-hardware.md 16 KB
- platforms.md 22 KB
- tools-advanced-2.md 14 KB
- tools-advanced.md 12 KB
- tools-dynamic.md 24 KB
- tools-emulation.md 13 KB
- tools.md 16 KB
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 · 168 lines · 125 tokens per session scan A e73cd18a0040
ctf-reverse is a skill published in the GitHub repository ljagiello/ctf-skills (3,223 stars, last pushed 16d ago), licensed MIT. It adds 125 tokens to every session and 3,181 once invoked, about $0.0006 per session on Opus 5. A static security scan graded it A with 0 findings. It is 84% identical to reverse-engineering, differing in 95 lines, and is treated as a copy.
Other skills, from other repositories
audit-ppmplugin
Statically audit a built .ppmplugin before wrap testing. Checks archive layout, manifest compatibility, bundle consistency, Android DEX integrity and SDK leakage, iOS framework structure, native source-to-receiver alignment, and the PCF composite-key/sendAsync transport contract. Reports CRITICAL, WARNING, and INFO…
debug-extension
Diagnose and fix failures in a built third-party .ppmplugin control: crashes, silent no-ops, PCF error outputs, or incorrect behavior. Uses the reported symptom, shared/error-codes.md, and file-level evidence to trace the manifest, Android/iOS modules, PCF dispatch, and build configuration. Produces a ranked…
generate-ppmplugin-manifest
Validate, reconcile to the chosen target(s), and stage the manifest.json for a .ppmplugin bundle. In the normal flow the committed ./manifest.json already exists (authored by /generate-native-extension), so this stage reads it, runs the plugin's upload-compatibility checks locally as a pre-flight gate (name regex…
diagnose
Root-cause a failing or wrong empirical result with a disciplined reproduce → minimise → hypothesise → instrument → fix loop, instead of guessing-and-poking. Use when the user says "why is my regression wrong", "this number changed", "my script errors out", "the result won't reproduce", "debug this", "this estimate…
redteam-reverse-detail-pack
Domain routing and boundary guidance for authorized reverse engineering analysis, including decompilation, debugging, protocol reversing, firmware extraction, and deobfuscation. Use when a task belongs to the reverse engineering domain and needs scope, evidence, pivot, or exit criteria.
performance-smell-detection
Detect potential code-level performance smells in Java - streams, collections, boxing, regex, object creation. Provides awareness, not absolutes - always measure before optimizing. For JPA/database performance, use jpa-patterns instead.