FlashHax is an exploit that was found by Fullmetal5. It's an implementation of CVE-2016-0974 for the Wii Internet Channel.
You can find more information about the FlashHax exploit on its Github page or
this GBAtemp thread.
MrBean took a Wiimmfi patcher and embedded it within this FlashHax exploit, which allows you to run a Wiimmfi patcher
just by going to a particular web page in the Wii's Internet Channel.
Due to the fact that this exploit is a bit unreliable (it sometimes takes a couple attempts to work) and the fact that the
Internet Channel can no longer be downloaded on Wiis that don't already have it, we usually recommend using the str2hax EULA exploit instead.
There's no archive or program that needs to be downloaded in order to use FlashHax.
All you need to do is make sure your Wii is running in 60Hz mode, then open the following webpage in the Wii Internet Channel:
Add the page to the browser favorites by clicking the Star icon, then the "Add Favorite" button; and then exit back to the Wii menu by pressing HOME.
Open the Internet Channel again and access the favorite you just added, and the Wiimmfi Patcher should start.
Note that this exploit isn't 100% reliable, if you are stuck on the page and the Wiimmfi Patcher does not start, just restart the console and try again.
If you run into UPnP-related issues (like the patcher getting stuck at the "Init network ..." or "add UPnP port forward" steps for more than 10 seconds)
you can press the Minus button on your Wii Remote, or the Y button on your Gamecube controller as soon as the patcher loads to get around that.
If that happens to you, please let us know so we can fix this issue for the future.