A quick search finds the details...
How to Access Metro Style Apps Installation Folder in Windows 8
\Program Files\WindowsApps
Why is this a problem?
Because it is easy to turn a trail to a full app, or to remove adds, or to hack apps.
NEVER save any server access code or password to an app, in particular not well encrypted.
This similar to "rooting" a mobile phone or a tablet.
Let's hope that Microsoft will do a better job protecting the apps on Windows 8.1. Keeping "mobile" OS separate from "desktop" would be better. If Microsoft has created WinRT as a virtual machine on "Windows 8 Desktop", upgrade from Windows 7 would be trivial decision (no big changes), and all "goodness" of WinRT Apps would still be there on every desktop... Anyway...
There is a reason why iOS is separate from OS X...