This indicates an attack attempt to exploit a Security Bypass vulnerability in the InduSoft Web Studio.
The vulnerability is due to improper authentication in the vulnerable application when handling a malicious request. A remote attacker may be able exploit this to execute arbitrary code on vulnerable machines.
Schneider Electric InduSoft Web Studio 188.8.131.52 and prior
System Compromise: Remote attackers can gain control of vulnerable systems
Apply the most recent upgrade or patch from the vendor