Assuming your cider wasn't really weak then there isn't much nasty stuff that will survive:
a) 5-7% alcohol solution, that's why we use it to preserve fruit :D
b) 5-7% acetic acid solution, that's why we use it for pickling! :D
If it smells like vinegar, it probably is. The smell is unmistakable. If you got a horrible mouldy mess on top that's what's called a "mother" and would definately confirm you as the proud owner of so much vinegar. 9 litres, you poor sod.
Pickling would be my realistic option. Needs to be 5% acetic though. If your ABV was 5% or more you're laughing.
Or...Put into small bottles as christmas presents? Pretend that you actually MEANT to do this? 8)
Anyway...I am sorry for your loss. I'd be gutted to lose 2 DJs of booze. Don't be discouraged, grab this year's apples and chalk this (pretty rare) occurence in the joys of brewing up to experience.