It's actually even worse than that, OP's exploit only scratches the surface of what's wrong with Steam's security model on Windows. The whole program directory

It's actually even worse than that, OP's exploit only scratches the surface of what's wrong with Steam's security model on Windows. The whole program directory is world writable including the Steam service binary which runs with local system permissions, and it's been this way for YEARS. See: https://news.ycombinator.com/item?id=20633929 https://news.ycombinator.com/item?id=20633929