I had a somewhat similar problem and found the following solution:
1) Open the Master Slide;
2) Select "Colors..." at the top of the Master Slide;
3) At the "Theme colors" dialog (right-hand side of the screen), select "Link";
4) Pick the desired link color and it is finished...
As You can see from the prefix it's JPEG file encoded by base64 binary-to-text encoding scheme. So, it's not a hyperlink but the whole file instead.
Technically, You could use this in HTML, CSS, etc to save some extra requests and/or issues with offsite resource not being available anymore.
Various browsers and scrapers used to use that just to download ...