Siemens SIMATIC WinCC

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: Low attack complexity
• Vendor: Siemens
• Equipment: SIMATIC PCS 7, SIMATIC WinCC
• Vulnerability: Classic Buffer Overflow

2. RISK EVALUATION

Successful exploitation of this vulnerability could allow a local attacker to cause a denial-of-service condition in the runtime of the SCADA system.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following versions of Siemens SIMATIC PCS 7 and SIMATIC WinCC, a SCADA system, are affected:

• Siemens SIMATIC PCS 7 V9.1: All versions before V9.1 SP2 UC04
• Siemens SIMATIC WinCC Runtime Professional V17: All versions
• Siemens SIMATIC WinCC Runtime Professional V18: All versions
• Siemens SIMATIC WinCC Runtime Professional V19: All versions before V19 Update 1
• Siemens SIMATIC WinCC V7.5: All versions before V7.5 SP2 Update 16
• Siemens SIMATIC WinCC V8.0: All versions

3.2 Vulnerability Overview

3.2.1 BUFFER COPY WITHOUT CHECKING SIZE OF INPUT ('CLASSIC BUFFER OVERFLOW') CWE-120

The affected products do not properly validate the input provided in the login dialog box. An attacker could leverage this vulnerability to cause a persistent denial-of-service condition.

CVE-2023-50821 has been assigned to this vulnerability. A CVSS v3.1 base score of 6.2 has been calculated; the CVSS vector string is (AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

A CVSS v4 score has also been calculated for CVE-2023-50821. A base score of 6.9 has been calculated; the CVSS vector string is (CVSS4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/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

Siemens reported this vulnerability to CISA.

4. MITIGATIONS

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

• All affected products: Activate SIMATIC Logon in the User Administrator of the SIMATIC PCS 7 Operator Stations
• SIMATIC WinCC Runtime Professional V17: Currently no fix is available
• SIMATIC WinCC Runtime Professional V18: Currently no fix is available
• SIMATIC WinCC V8.0: Currently no fix is available
• SIMATIC WinCC Runtime Professional V19: Update to V19 Update 1 or later version
• SIMATIC WinCC V7.5: Update to V7.5 SP2 Update 16 or later version
• SIMATIC PCS 7 V9.1: Update to V9.1 SP2 UC04 or later version

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-730482 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. This vulnerability is not exploitable remotely.

5. UPDATE HISTORY

• April 11, 2024: Initial Publication

• Siemens