In addition to Dave's suggestion I'd recommend looking at the Shadow/Highlight effect to brighten the shadows as that should allow good control over affecting the colors specifically in areas of shadow.
You could duplicate the footage, adjust the shadows using Shadow/Highlight to your taste, then selectively mask the background out of that layer with a large feather so as to retain the separation between your subject and the wall.
Just be careful of giving the subject a 'glowing' look. Depending on the accuracy required, and money being poured in, I would often prefer to create masks for this purpose that simulate a light cast on the back wall falling off. This doesn't require as much accuracy around the detailed edges of the foreground.