vm-and-bytecode-reverse

Reconstruct custom VM opcodes and bytecode execution logic from binaries.

11|4|Updated Jun 7, 2026

Search Tags:#bytecode #ctf #reverse engineering #virtual machine #disassembler #opcode analysis

Ready to run

npx skills add https://github.com/sayseven7/frameseven --skill vm-and-bytecode-reverse-sayseven7

💬 Prompt for ChatGPT / Claude Chat▼

Please help me install this Agent Skill.
Skill: vm-and-bytecode-reverse
Source: https://github.com/sayseven7/frameseven/tree/main/internal/mcp/skills/vm-and-bytecode-reverse
Command: npx skills add https://github.com/sayseven7/frameseven --skill vm-and-bytecode-reverse-sayseven7

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

This Skill helps you understand and dismantle custom virtual machines and bytecode interpreters when normal decompilation fails, turning opaque execution loops into readable behavior.

Core Features & Use Cases

Dispatcher identification: Recognize switch-based, table-based, and if-chain interpreters hidden inside binaries.
Opcode reconstruction: Map handlers, operands, and side effects to rebuild a custom instruction set architecture.
Bytecode analysis: Write a disassembler or trace execution to recover logic from protected software or CTF challenges.
Maze and puzzle solving: Extract grids, infer movement encodings, and compute valid paths for VM-driven maze tasks.
Protector research: Analyze VM-style obfuscation patterns used by commercial protectors or academic obfuscators.

Quick Start

Use this skill to analyze the attached binary or bytecode dump and reconstruct its opcode handlers, dispatcher logic, and execution semantics.

Frequently Asked Questions about vm-and-bytecode-reverse

High-intent search queries and answers about installing and using this skill.

FAQPage Schema

How do I reverse engineer a custom virtual machine when decompilation fails?▼

To reverse engineer a custom virtual machine, you must identify the dispatcher loop, map opcode handlers, and trace execution semantics to rebuild the hidden instruction set architecture. This process transforms opaque bytecode execution loops into readable behavior.

How do I identify a dispatcher loop in a protected binary?▼

A dispatcher loop in a protected binary is identified by recognizing switch-based, table-based, or if-chain interpreters hidden inside the code. Tracing these control flow structures reveals how the custom virtual machine routes opcodes to their handlers.

What is the best way to map custom opcodes during bytecode analysis?▼

The best way to map custom opcodes is by tracing handler functions, operands, and side effects to reconstruct the instruction set architecture. This opcode reconstruction reveals the underlying semantics of the protected bytecode stream.

How do I solve a VM-driven maze puzzle in a CTF challenge?▼

To solve a VM-driven maze puzzle, you extract the grid layout, infer movement encodings from the reconstructed opcodes, and compute the valid path. This requires analyzing the custom bytecode to understand the movement logic.

Does this approach work for analyzing VM-style obfuscation from commercial protectors?▼

Yes, this approach works for analyzing VM-style obfuscation used by commercial protectors or academic obfuscators. Reconstructing the custom interpreter logic helps you dismantle the virtual machine and recover the original control flow.

Why does normal decompilation fail on custom bytecode interpreters?▼

Normal decompilation fails on custom bytecode interpreters because the program flow is hidden inside an opaque execution loop rather than standard machine code. Recovering logic requires disassembling the bytecode and mapping the custom instruction handlers.