Siemens Desigo PXC (Update C)

1. EXECUTIVE SUMMARY

• CVSS v3 9.8
• ATTENTION: Exploitable remotely/low skill level to exploit
• Vendor: Siemens
• Equipment: Desigo PXC
• Vulnerability: Improper Authentication

2. UPDATE INFORMATION

This updated advisory is a follow-up to the advisory update titled ICSA-18-025-02B Siemens Desigo PXC that was published March 22, 2018, on the NCCIC/ICS-CERT website.

3. RISK EVALUATION

Successful exploitation of this vulnerability could allow unauthenticated remote attackers to upload malicious firmware without prior authentication.

4. TECHNICAL DETAILS

4.1 AFFECTED PRODUCTS

This advisory covers only the Desigo PX Controller product line and not the Apogee PX Controller product line.

Siemens reports that the vulnerability affects all versions prior to v4.10.111, v5.00.171, v5.10.069, and v6.00.204 of the following products:

• Desigo Automation Controllers Compact PXC12/22/36-E.D,
• Desigo Automation Controllers Modular PXC00/50/100/200-E.D,
• Desigo Automation Controllers PXC00/64/128-U with Web module,
• Desigo Automation Controllers for Integration PXC001-E.D, and
• Desigo Operator Unit PXM20-E

4.2 VULNERABILITY OVERVIEW

4.2.1    IMPROPER AUTHENTICATION CWE-287

A remote attacker with network access to the device could potentially upload a new firmware image to the devices without prior authentication.

CVE-2018-4834 has been assigned to this vulnerability. A CVSS v3 base score of 9.8 has been assigned; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).

4.3 BACKGROUND

• CRITICAL INFRASTRUCTURE SECTORS: Commercial Facilities
• COUNTRIES/AREAS DEPLOYED: Worldwide
• COMPANY HEADQUARTERS LOCATION: Germany

4.4 RESEARCHER

Can Demirel and Melih Berk Eksioglu from Biznet Bilisim reported this vulnerability to Siemens.

5. MITIGATIONS

Siemens has provided updated versions that fix the vulnerability for the affected products. Siemens recommends users update to version v4.10.111, v5.00.171, v5.10.069, or v6.00.204 or later. Updates can be obtained from Siemens customer support or a local partner.

As a general security measure, Siemens strongly recommends protecting network access to the devices with appropriate mechanisms. Siemens advises configuring the environment according to Siemens operational guidelines in order to run the devices in a protected IT environment.

https://www.siemens.com/cert/operational-guidelines-industrial-security

NCCIC recommends users take defensive measures to minimize the risk of exploitation of this vulnerability. Specifically, users should:

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

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

NCCIC also provides a section for control systems security recommended practices on the ICS-CERT web page. Several recommended practices are available for reading and download, including Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies.

Additional mitigation guidance and recommended practices are publicly available on the ICS-CERT website in the Technical Information Paper, ICS-TIP-12-146-01B–Targeted Cyber Intrusion Detection and Mitigation Strategies.

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

No known public exploits specifically target this vulnerability