AI agent skill · by @transilienceai

Reverse Engineering

Static and dynamic reverse engineering — ELF/PE analysis, custom-VM bytecode, packed binaries, anti-debug bypass, Frida hooking.

Archived 2026-10-23 · Source updated 2026-07-29 · License: MIT. Check the original repository for the latest version.

SKILL.md instructions

# Reverse Engineering

## Scope

Reverse engineering compiled binaries (ELF, PE, Mach-O) and bytecode artifacts to recover algorithms, validate inputs, or build static solvers. Focused on the recurring CTF / malware-analysis pattern of a host binary that loads a "program" file under a custom ISA — recognising the dispatcher loop, mapping opcodes to Python lambdas, and inverting the transformation chain in pure Python without executing the host. Also covers callfuscation (control-flow chunking), MBA (mixed boolean-arithmetic) operator obfuscation, encrypted-handler tricks, and three-layer deobfuscation pipelines.

## When to use

- A binary plus a "program data" file are delivered together and the binary appears to be an interpreter (themed opcode names, dispatcher switch / jump table).
- Disassembly reveals a `while(true){ op = mem[pc++]; switch(op){...}; }` style loop or jump-table indexed by opcode.
- The binary is heavily obfuscated (callfuscation, MBA wrappers, encrypted handlers in `.data` decrypted to RWX at startup).
- You need to recover an algorithm or check function from native code without dynamic execution (anti-debug, wrong arch, no TTY).
- Static-first reverse engineering is preferred (faster, more reliable than emulator chains).

## References

- [reference/custom-vm-bytecode.md](reference/custom-vm-bytecode.md) — recognising and inverting custom stack/register/tape VMs; callfuscation linearization; MBA operator identification; encrypted-handler decryption.