CVE-2018-11763 : Security Advisory and Response

Apache HTTP Server versions 2.4.17 to 2.4.34 are vulnerable to a Denial of Service (DoS) attack via continuous SETTINGS frames in HTTP/2 connections.

Understanding CVE-2018-11763

This CVE entry highlights a vulnerability in Apache HTTP Server that allows clients to exhaust server resources without triggering connection timeouts.

What is CVE-2018-11763?

Clients can occupy a connection, server thread, and CPU time by sending continuous, large SETTINGS frames in Apache HTTP Server versions 2.4.17 to 2.4.34.
This vulnerability specifically impacts HTTP/2 connections.
Mitigation involves disabling the h2 protocol to prevent exploitation.

The Impact of CVE-2018-11763

Allows attackers to consume server resources without triggering connection timeouts.
Can lead to server unresponsiveness and potential service disruption.

Technical Details of CVE-2018-11763

Apache HTTP Server vulnerability details and affected systems.

Vulnerability Description

Vulnerability in mod_http2 allows DoS attacks via continuous SETTINGS frames.

Affected Systems and Versions

Product: Apache HTTP Server
Vendor: Apache Software Foundation
Versions: 2.4.17 to 2.4.34

Exploitation Mechanism

Attackers exploit HTTP/2 connections by sending large SETTINGS frames continuously.

Mitigation and Prevention

Protecting systems from CVE-2018-11763 and implementing security measures.

Immediate Steps to Take

Disable the h2 protocol in Apache HTTP Server.
Monitor server resources for unusual activity.
Implement rate limiting for incoming requests.

Long-Term Security Practices

Regularly update Apache HTTP Server to the latest version.
Implement network-level protections such as firewalls and intrusion detection systems.

Patching and Updates

Apply patches provided by Apache Software Foundation to address the vulnerability.