About the only suggestion I can offer, short of removing the bottom 2
feet of the framed wall and replacing with concrete block, is to remove
the lower foot of siding, replace with as thick a flashing material as
you can find, sealed to the slab in some manner. Not a correct fix, and
it will leak when the seal fails, but better than having wet wood. Or
trench the area and put in a retaining wall. put in a drain to a low
spot, fill trench with gravel, and dress it up with some potted shrubs.

So you mean to remove the lower 12" of siding, then put in some kind
of metal that is 12" tall, bonded to the foundation, then to cover it
with new siding?

I just looked it up and Azek makes a 5/8" trim piece as wide as wide
as 15" so that may be my best option for a replacement.