Not that it's not possible in Singapore, but: if you have a mortgage, you probably benefited from SIBOR rate rigging.
There were two types of rigging that went on.
Before 2008, banks were nudging the rate up and down to suit their fixing risks. The net effect was small - perhaps a basis point or two either way at the absolute max - and anyway, the manipulation went both ways, so the net effect on your mortgage would be approximately nothing.
During and after the GFC, banks were manipulating LIBOR (and presumably SIBOR) lower to make themselves look stronger to the rest of the market. And if SIBOR was rigged lower, then you paid less on your mortgage than you otherwise would have.
I wouldn't go so far as to say you owe the bank money, but... you'd almost certainly come off second best if you went to court claiming that SIBOR rigging cost you money.
Update: I screwed up my math about SOR-linked mortgages - they're in exactly the same situation as SIBOR-linked mortgages. If USD Libor was manipulated lower, and the forward points were held constant, then SGD SOR was also lower than it would've been without Libor manipulation. Basically if you had a floating-rate mortgage you benefited from Libor/Sibor rigging, no matter what benchmark you peg to.