OPC UA NET Standard Stack, Authentication Bypass, CVE-2025-XXXX (Moderate)

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How the CVE Works:

The vulnerability in the OPC UA .NET Standard Stack (CVE-2025-XXXX) allows an unauthorized attacker to bypass application authentication when the stack is configured to use HTTPS endpoints. This occurs due to improper validation of client certificates during the TLS handshake process. Specifically, the stack fails to enforce mutual authentication, enabling an attacker to impersonate a legitimate client or server. By exploiting this flaw, an attacker could gain unauthorized access to sensitive data or manipulate OPC UA communications, potentially disrupting industrial control systems (ICS) or other critical infrastructure relying on this stack.

DailyCVE Form:

Platform: OPC UA .NET Standard Stack

Version: < 1.5.374.158

Vulnerability: Authentication Bypass

Severity: Moderate

Date: Mar 3, 2025

What Undercode Say:

Exploitation:

  1. Exploit Command: Use tools like `openssl` to craft malicious client certificates and test for improper validation. 
    openssl req -newkey rsa:2048 -nodes -keyout fake_client.key -out fake_client.csr
openssl x509 -req -in fake_client.csr -CA attacker_ca.crt -CAkey attacker_ca.key -CAcreateserial -out fake_client.crt -days 365
  2. Exploit URL: Test against vulnerable OPC UA servers using HTTPS endpoints.
    Example: `https://:4840`

Protection:

  1. Update: Upgrade to the patched version `1.5.374.158` or later. 
    nuget install OPCFoundation.UA-.NETStandard -Version 1.5.374.158
  2. Configuration: Enforce mutual TLS authentication and validate client certificates strictly.

Example configuration in `appsettings.json`:

{
"SecurityConfiguration": {
"UseValidatedCertificates": true,
"RejectUnknownCertificates": true
}
}

3. Monitoring: Use network monitoring tools like Wireshark to detect unauthorized certificate usage.

Filter: `tls.handshake.certificate`

References:

Additional Commands:

  • Check Version: 
    dotnet list package --include-transitive | grep OPCFoundation.UA-.NETStandard
  • Test Server: 
    curl -v --key fake_client.key --cert fake_client.crt https://:4840

By following these steps, organizations can mitigate the risk posed by this vulnerability and secure their OPC UA implementations.

References:

Reported By: https://github.com/advisories/GHSA-4rcc-7pg7-f57f
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