Foster helped Blues to the 2011 Carling Cup victory and still has many friends working at the club, both on and off the pitch.
He hopes the eventual takeover situation will be resolved soon.
"I don't know if it's affecting them or not, but obviously their league position isn't great and this seems to be a cloud hanging over them," Foster told the Birmingham Mail.
"I hope it does get resolved soon - it will be in everyone's best interests if it does.
"It's just a lovely club. I have nothing but good and positive things to say about Birmingham. It's a good, family-orientated club like West Brom.
"I hope they get to where they should be, which is in the Premier League. They have a big fan base, they're a big club in a big city - they should be in the top flight.
"I'm not going to bad-mouth anyone but something doesn't seem right. I hope it will get resolved sooner rather than later."