This indicates an attack attempt to exploit a remote Code Execution vulnerability in Unitrends Backup.
The vulnerability is due to lack of authentication validation in the application when handling a crafted request. It may allow remote attackers to execute arbitrary code on vulnerable systems via a crafted request.
Unitrends Backup version 9.1 and prior
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply latest upgrade from the Vendor.