This indicates an attack attempt against a Denial of Service vulnerability in Mikrotik Syslog Server.
The vulnerability is caused by an error when the vulnerable software handles a overlong syslog message. It allows a remote attacker to crash vulnerable systems via a crafted syslog message.
Mikrotik Syslog Server for Windows v 1.15
Denial of Service: Remote attackers can crash vulnerable systems.
Currently we are unaware of any vendor supplied patch for this issue.