This indicates an attack attempt to exploit a system through Niteris (CottonCastle) Exploit Kit.
Niteris (CottonCastle) Exploit Kit attempts to compromise a system through various software vulnerabilities.
Niteris (CottonCastle) Exploit Kit
System Compromise: Remote attackers can gain control of vulnerable systems.
Monitor the traffic from that network for any suspicious activity.
Update systems and applications to the latest version.