Slow HTTP DoS (Denial of Service) Attack
Your all web servers are vulnerable to Slow HTTP DoS (Denial of Service) attacks.
Slowloris and Slow HTTP POST DoS attacks rely on the fact that the HTTP protocol, by design, requires requests to be completely received by the server before they are processed. If an HTTP request is not complete, or if the transfer rate is very low, the server keeps its resources busy waiting for the rest of the data. If the server keeps too many resources busy, this creates a denial of service.
Time difference between connections: 10006 ms
The impact of this vulnerability:
A single machine can take down another machine's web server with minimal bandwidth and side effects on unrelated services and ports.
Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Use CloudFlare with current application and it'll resolve the issue but that's not permanent solution, kindly make the changes in the real server to prevent this kind of attacks.