This indicates an attack attempt to exploit an Arbitrary File Upload vulnerability in Symantec Workspace Streaming.
The vulnerability is due to insufficient sanitizing of user supplied inputs in the application when handling crafted HTTP requests. A remote attacker can exploit this to gain unauthorized access to sensitive information via a crafted request. Also a remote attacker may be able to execute arbitrary code through exploiting this vulnerability.
Symantec Workspace Streaming 7.5.x and prior
Information Disclosure: Remote attackers can gain sensitive information from vulnerable systems.
System Compromise: Remote attackers can gain control of vulnerable systems.
Refer to the vendor's website for suggested workaround.