A tiny-VM lock | Hunt the Flag

Labs need a computer

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Files

rev-vm.zip
Size: 1.5 KB
SHA-256
ffb9a3487e208ce07ee3577691036397001903dbf098d345c0fd9b7c94e0d243
Download

After downloading, compare the file SHA-256 with the value shown here to make sure it arrived intact.

Tools you may need

node
To run the VM and trace execution.

Scenario

A small Ravens VM runs a per-byte program over your input and compares it to an embedded target. Each op is reversible, so invert them on the target to recover the input, the flag. The artifact is inert: it reads input and prints a verdict only — no network, no writes, no persistence.

What you are looking at

You download rev-vm.zip with vm.js, program.txt and target.txt; the VM transforms each byte by a short program and compares to the target.

Goal

Trace the VM program and invert its ops on the target to recover the flag.

What counts as solved

You enter the correct flag.

Method checklist

Tick each step as you work through it. The steps are the method, not the answer.

Read vm.js and program.txt.
Understand the per-byte op sequence.
Invert each op on the target bytes.
Assemble the bytes into text with the flag.

Hints

You have not revealed a hint yet. Ask the falcon when you need one.