I think we should be looking within the rocks, not underneath them. From a NASA policy paper on Mars (2009):
"Direct evidence of life might not beeverywhere on the surface (the premise of the Viking) but biosignatures could still
be present, within the rocks at shallow depth."
Life within rocks = endoliths
So, they drilled into a rock. Now they're having a press conference. Gee, I wonder what they might have found?