Try wiping down with acetone. Will clean it up nicely. Be careful not to get the residue on the hull. Works well. Good luck.
Ditto on the acetone. Here are a few tips I've learned over time.
Scrub the rail with boat soap and rinse well with water. Make sure the rail is 100% dry before using the acetone.
Clean small sections of rail with a soft rag and acetone making sure to use a clean section of the rag as the one you are using gets dirty. If you don't use a clean rag, the acetone will reapply the gunk back on the rub rail.
Sit back and say to yourself, Gee I didn't know the rub rail was that color!
You can use polish or sealants on the rub rail to extend its new shine. I use Mop and Glow floor treatment. Regardless of hat you use, The life of the shine depends very much on your conditions, particularly the sunlight strength