Cisco Talos would like to acknowledge Anna Bennett and Brandon White of Cisco Talos and Phillip Schafer, Mike Moran, and Becca Lynch of the Duo Security Research team for their research that led to the identification of these attacks.
Cisco Talos is actively monitoring a global increase in brute-force attacks
I found just white listing cidrs from your country the most effective way to reduce this log spam. I only use keys anyway so the attempts are pointless.