Short version: topic
I want to use a specific 3rd party theme for Windows. I'm already using an open source solution which I've compiled myself to disable Window's restriction on Themes.
In the past, when using 3rd party theme related mods that come with DLLs (for example authui.dll for the login ui, or imageres.dll for modding system icons), I avoid using unknown DLLs by simply copying the unknown DLL's theme related resources (such as Bitmaps, Icon groups or UI scripts) unto it's virgin MS Dll counterpart. I call this resource grafting, where resource are changed but the executable elements of DLLs or exes are left alone.
Going back to the theme I want to install, I used sha256 hashing to determine that only aero.msstyles which is also modifiable by resource hacker. So I did the same thing I usually do and transferred resources from the third party theme to Window's own aero.msstyles. Problem is that I ran into a type of resource that I am unable to read or know the contents of. It's called VARIANT. From some experiments done in a VM, it seems to be some kind of binary UI script that resource hacker is unable to decompile. I usually like to be able to read any UI scripts that I transfer but I am unable to do so with this one.
Would this constitute any real security risks? Can UI scripts be side-loaded with some kind of exploit? Seems unlikely to me since the function of a theme file (msstyle) is to coordinate the appearance of the system UI but I don't know enough about the inner working of the whole theming system to be sure. I thought I'd get some other point of views before I take the theme out of the Virtual Machine.