ctf-reverse
ctf-reverse is a structured reference for reverse engineering techniques across compiled binaries, mobile apps, WebAssembly, firmware, and virtualized code. Use it when CTF challenges require analyzing obfuscated, packed, or anti-analysis protected targets before exploitation, covering static analysis tools like Ghidra and radare2, dynamic analysis with Frida and angr, emulation frameworks, and advanced deobfuscation strategies. Do not use when exploitation paths are already known or for pure forensics and standalone cryptography.
git clone --depth 1 https://github.com/ljagiello/ctf-skills /tmp/ctf-reverse && cp -r /tmp/ctf-reverse/ctf-reverse ~/.claude/skills/ctf-reverseSKILL.md
# CTF Reverse Engineering Quick reference for RE challenges. For detailed techniques, see supporting files. ## Prerequisites **Python packages (all platforms):** ```bash 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):** ```bash apt install gdb radare2 binutils strace ltrace apktool upx ``` **macOS (Homebrew):** ```bash brew install gdb radare2 binutils apktool upx ghidra ``` **radare2 plugins:** ```bash r2pm -ci r2ghidra # Native Ghidra decompiler for radare2 ``` **Manual install:** - pwndbg — Linux: [GitHub](https://github.com/pwndbg/pwndbg), macOS: `brew install pwndbg/tap/pwndbg-gdb` ## Additional Resources - [tools.md](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](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](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](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](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.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](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](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](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](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](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](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](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-c
Provides AI and machine learning techniques for CTF challenges. Use when attacking ML models, crafting adversarial examples, performing model extraction, prompt injection, membership inference, training data poisoning, fine-tuning manipulation, neural network analysis, LoRA adapter exploitation, LLM jailbreaking, or solving AI-related puzzles.
Provides cryptography attack techniques for CTF challenges. Use when attacking encryption, hashing, signatures, ZKP, PRNG, or mathematical crypto problems involving RSA, AES, ECC, lattices, LWE, CVP, number theory, Coppersmith, Pollard, Wiener, padding oracle, GCM, key derivation, or stream/block cipher weaknesses.
Provides digital forensics and signal analysis techniques for CTF challenges. Use when analyzing disk images, memory dumps, event logs, network captures, cryptocurrency transactions, steganography, PDF analysis, Windows registry, Volatility, PCAP, Docker images, coredumps, side-channel power traces, DTMF audio spectrograms, packet timing analysis, CD audio disc images, or recovering deleted files and credentials.
Provides malware analysis and network traffic techniques for CTF challenges. Use when analyzing obfuscated scripts, malicious packages, custom crypto protocols, C2 traffic, PE/.NET binaries, RC4/AES encrypted communications, YARA rules, shellcode analysis, memory forensics for malware (Volatility malfind, process injection detection), anti-analysis techniques (VM/sandbox detection, timing evasion, API hashing, process injection, environment checks), or extracting malware configurations and indicators of compromise.
Provides miscellaneous CTF challenge techniques for problems that do not cleanly fit the main categories. Use for encoding puzzles, pyjails, bash jails, RF/SDR, DNS oddities, unicode tricks, esoteric languages, QR or audio puzzles, constraint solving, game theory, unusual sandbox escapes, and hybrid logic puzzles. Prefer a more specific skill first when the challenge is mainly web, pwn, reverse, forensics, malware, OSINT, or crypto. Treat this as the fallback skill for genuine cross-category or edge-case challenges, not the default starting point.
Provides open source intelligence techniques for CTF challenges. Use when gathering information from public sources, social media, geolocation, DNS records, username enumeration, reverse image search, Google dorking, Wayback Machine, Tor relays, FEC filings, or identifying unknown data like hashes and coordinates.
Provides binary exploitation techniques for CTF challenges. Use when you already have a vulnerable native target or service and need to turn memory corruption or low-level primitives into code execution or privilege escalation, such as buffer overflows, format strings, heap bugs, ROP, ret2libc, shellcode, kernel exploitation, seccomp bypass, sandbox escape, or Windows/Linux exploit chains. Do not use it when the main blocker is understanding what the binary does; use reverse engineering first. Do not use it for pure web bugs, disk or packet forensics, or standalone crypto/math challenges.
Provides web exploitation techniques for CTF challenges. Use when the target is primarily an HTTP application, API, browser client, template engine, identity flow, or smart-contract frontend/backend surface, including XSS, SQLi, SSTI, SSRF, XXE, JWT, auth bypass, file upload, request smuggling, OAuth/OIDC, SAML, prototype pollution, and similar web bugs. Do not use it for native binary memory corruption, reverse engineering of standalone executables, disk or memory forensics, or pure cryptanalysis unless the web flaw is still the main path to the flag.