As of January 10, 2023, CISA will no longer be updating ICS security advisories for Siemens product vulnerabilities beyond the initial advisory. For the most up-to-date information on vulnerabilities in this advisory, please see Siemens’ ProductCERT Security Advisories (CERT Services | Services | Siemens Global). 

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1. EXECUTIVE SUMMARY

CVSS v4 6.9
ATTENTION: Exploitable remotely/low attack complexity
Vendor: Siemens
Equipment: Mendix Runtime
Vulnerability: Observable Response Discrepancy

2. RISK EVALUATION

Successful exploitation of this vulnerability could allow unauthenticated remote attackers to distinguish between valid and invalid usernames.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following versions of Siemens Mendix Runtime, are affected:

Mendix Runtime V8: All versions only if the basic authentication mechanism is used by the application
Mendix Runtime V9: All versions prior to V9.24.26 only if the basic authentication mechanism is used by the application
Mendix Runtime V10: All versions prior to V10.14.0 only if the basic authentication mechanism is used by the application
Mendix Runtime V10.6: All versions prior to V10.6.12 only if the basic authentication mechanism is used by the application
Mendix Runtime V10.12: All versions prior to V10.12.2 only if the basic authentication mechanism is used by the application

3.2 Vulnerability Overview

3.2.1 OBSERVABLE RESPONSE DISCREPANCY CWE-204

The authentication mechanism of affected applications contains an observable response discrepancy vulnerability when validating usernames. This could allow unauthenticated remote attackers to distinguish between valid and invalid usernames.

CVE-2023-49069 has been assigned to this vulnerability. A CVSS v3.1 base score of 5.3 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N).

A CVSS v4 score has also been calculated for CVE-2023-49069. A base score of 6.9 has been calculated; the CVSS vector string is (CVSS4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N).

3.3 BACKGROUND

CRITICAL INFRASTRUCTURE SECTORS: Critical Manufacturing
COUNTRIES/AREAS DEPLOYED: Worldwide
COMPANY HEADQUARTERS LOCATION: Germany

3.4 RESEARCHER

Raquel Gálvez from Hispasec Sistemas reported this vulnerability to Siemens. Siemens reported this vulnerability to CISA.

4. MITIGATIONS

Siemens has identified the following specific workarounds and mitigations users can apply to reduce risk:

Mendix Runtime V8: Currently no fix is available
Mendix Runtime V9: Update to V9.24.26 or later version
Mendix Runtime V10: Update to V10.14.0 or later version
Mendix Runtime V10.6: Update to V10.6.12 or later version
Mendix Runtime V10.12: Update to V10.12.2 or later version

Do not use basic authentication, but setup an alternative authentication module (e.g. SAML, MendixSSO), or your own Identity Provider (IDP)

As a general security measure, Siemens recommends protecting network access to devices with appropriate mechanisms. To operate the devices in a protected IT environment, Siemens recommends configuring the environment according to Siemens’ operational guidelines for industrial security and following recommendations in the product manuals.

Additional information on industrial security by Siemens can be found on the Siemens industrial security webpage

For more information see the associated Siemens security advisory SSA-097435 in HTML and CSAF.

CISA recommends users take defensive measures to minimize the risk of exploitation of this vulnerability, such as:

Minimize network exposure for all control system devices and/or systems, ensuring they are not accessible from the internet.
Locate control system networks and remote devices behind firewalls and isolating them from business networks.
When remote access is required, use more secure methods, such as Virtual Private Networks (VPNs), recognizing VPNs may have vulnerabilities and should be updated to the most current version available. Also recognize VPN is only as secure as the connected devices.

CISA reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures.

CISA also provides a section for control systems security recommended practices on the ICS webpage on cisa.gov/ics. Several CISA products detailing cyber defense best practices are available for reading and download, including Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies.

CISA encourages organizations to implement recommended cybersecurity strategies for proactive defense of ICS assets.

Additional mitigation guidance and recommended practices are publicly available on the ICS webpage at cisa.gov/ics in the technical information paper, ICS-TIP-12-146-01B–Targeted Cyber Intrusion Detection and Mitigation Strategies.

Organizations observing suspected malicious activity should follow established internal procedures and report findings to CISA for tracking and correlation against other incidents.

No known public exploitation specifically targeting this vulnerability has been reported to CISA at this time.

5. UPDATE HISTORY

September 12, 2024: Initial Publication