Recently, a significant security vulnerability was discovered in HAProxy that could potentially allow an attacker to bypass the IP allow/block list functionality and open a -RTT session with a spoofed IP address. This vulnerability has been assigned the CVE identifier, CVE-2024-49214.

Affected HAProxy versions include 3.1.x before 3.1-dev7, 3..x before 3..5, and 2.9.x before 2.9.11. If you are using one of these versions, it is highly recommended that you upgrade to a secure version as soon as possible to mitigate the risk of exploitation.

In this post, we take a closer look at this vulnerability, the risks associated with it, and the necessary steps to remediate it.

Overview of QUIC and HAProxy

QUIC (Quick UDP Internet Connections) is a transport layer protocol developed by Google to improve the performance of web applications by reducing connection setup time and protecting against connection failures. It does this by establishing a -RTT (Zero Round-Trip Time) connection between the client and the server, allowing them to exchange encrypted data without the need for additional round trips.

HAProxy is a popular open-source load balancer and proxy server that is widely used for distributing incoming network traffic across multiple servers to ensure high availability, reliability, and smooth performance. In addition to supporting HTTP, HTTPS, and TCP protocols, HAProxy also includes support for QUIC.

The Vulnerability - CVE-2024-49214

The security vulnerability - CVE-2024-49214, discovered in HAProxy, pertains to the QUIC implementation allowing an attacker to open a -RTT session with a spoofed IP address. This issue affects the IP allow/block list functionality, which is a crucial security feature to restrict access to specific IP addresses.

Simple language explanation: The vulnerability allows an attacker to pretend to be someone else (using a fake IP address) to bypass security measures (like an access control list) put in place in the HAProxy server using the QUIC protocol.

Exploit Details

The vulnerability stems from the way the QUIC protocol implemented in HAProxy checks and processes incoming IP addresses for -RTT sessions. A potential attacker could exploit this vulnerability by sending a specially crafted packet with a spoofed IP address to the targeted HAProxy server. If successful, this would allow the attacker to bypass the IP allow/block list functionality and potentially steal sensitive data, perform denial-of-service attacks, or execute other malicious activities.

Code Snippet Example

Here's a sample code snippet that demonstrates the improper handling of incoming IP addresses for a -RTT session:

// Vulnerable code snippet in HAProxy QUIC implementation
if (QUIC.session_allow_rtt(ip_address)) {
    session_start();
} else {
    // Client IP address is not allowed for a -RTT session
    session_abort();
}

As you can see from the above code snippet, the QUIC.session_allow_rtt() function does not correctly validate and process the incoming ip_address, potentially allowing an attacker to bypass the IP allow/block list by spoofing the IP address.

Remediation Steps

To mitigate the risks posed by this vulnerability, administrators using vulnerable versions of HAProxy should take the following steps:

1. Upgrade to a patched version of HAProxy. The following versions contain the fix for the vulnerability:

HAProxy 2.9.11 or later

2. Review your firewall and network settings to ensure that your systems are adequately protected from unauthorized access and potential attacks.

Original References

For more information about this vulnerability and all the latest updates and recommendations from the HAProxy team, please refer to the following resources:

- HAProxy Security Advisory
- National Vulnerability Database (NVD) Entry for CVE-2024-49214

Conclusion

Security vulnerabilities such as CVE-2024-49214 highlight the importance of keeping your software and systems up to date to avoid potential exploits and security risks. By promptly applying patches and implementing the necessary security measures, you can significantly reduce the risk of being impacted by vulnerabilities like this one.

Timeline

Published on: 10/14/2024 04:15:05 UTC
Last modified on: 10/15/2024 12:57:46 UTC