This indicates an attack attempt to exploit an Authentication Bypass Vulnerability in Zoho ManageEngine.
The vulnerability is due to lack of validation of user-supplied inputs. A remote, unauthenticated attacker could exploit this vulnerability by sending a crafted message to vulnerable server. Successful exploitation allows the attacker to access certain REST APIs that are not normally accessible.
Zoho ManageEngine Access Manager Plus before 4302
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the most recent upgrade or patch from the vendor.