Diagnosis
Most likely source is a loose or split drain hose connection at the back of the washer or a clogged/overflowing drain standpipe.
How to Fix It
Pull the washer out. Check where the drain hose connects to the washer pump. Ensure the clamp is tight. Check where the hose attaches to the standpipe or sink. It should only be inserted 4-6 inches; too deep causes siphoning.
If That Didn't Work
The leak could be from a cracked drain pump filter housing or a failed tub seal. Inspect the front-bottom area for cracks. The drain pump filter is behind the small kickplate.
Heads Up
Before moving the washer, turn off the water supply valves. Have towels ready. Electrical components are on the bottom; water can damage the drive motor or control board.