# Some Assembly Required 1

## Problem

> <http://mercury.picoctf.net:26318/index.html>

## Solution

1. The website loads an obfuscated javascript file. I spent a lot of time analyzing this file and realized that it performs an HTTP request and downloads the following string: `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`.
2. Decoding this string from base64 shows the flag at the end. This string is compiled WebAssembly. I researched decompiling WebAssembly, which can be done with `wasm-decompile` in [WebAssembly/wabt](https://github.com/WebAssembly/wabt). I also reversed a lot of the JavaScript unnecessarily. This might come in handy for the next challenge in this series.
3. The compiled wasm file can be found at [compiled.wasm](https://github.com/HHousen/PicoCTF-2021/blob/master/Web%20Exploitation/Some%20Assembly%20Required%201/compiled.wasm). This was created using `write_wasm.py` from `../Some Assembly Required 2`.

### Flag

`picoCTF{8857462f9e30faae4d037e5e25fee1ce}`


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