This indicates an attack attempt to exploit a Remote Code Injection Vulnerability in Denyall Suite and Dneyall Web Application Firewall.
The vulnerability is due to an error when the vulnerable software handles a HTTP Request. A remote attacker may be able to exploit this to inject arbitrary code to the vulnerable systems
DenyAll i-Suite LTS version 5.5 (5.5.0 to 5.5.12)
DenyAll i-Suite 5.6
DenyAll WAF 5.7
DenyAll WAF 6.0 to 6.4.0.
System Compromise: Remote attackers can gain control of vulnerable systems.
Upgrade to the latest version from the vendor.