Siemens SiPass integrated AC5102 / ACC-G2 and ACC-AP

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).

1. EXECUTIVE SUMMARY

• CVSS v3 7.8
• ATTENTION: Low attack complexity  
• Vendor: Siemens  
• Equipment: SiPass integrated AC5100, AC5102, AC5200, ACC-AP, Granta-MK3  
• Vulnerability: Improper Input Validation 

2. RISK EVALUATION

Successful exploitation of this vulnerability could allow an authenticated user to escalate privileges by injecting arbitrary commands executed with root privileges. 

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following software from Siemens is affected: 

• SiPass integrated AC5100 (ACC): All versions  
• SiPass integrated AC5102 (ACC-G2): All versions prior to V2.85.44 
• SiPass integrated AC5200 (ACC-Lite, ACC-4, ACC-8, ACC-16, ACC-32): All versions  
• SiPass integrated ACC-AP: All versions prior to V2.85.43 
• SiPass integrated Granta-MK3 (ACC-GRANTA): All versions  

3.2 VULNERABILITY OVERVIEW

3.2.1 IMPROPER INPUT VALIDATION CWE-20 

Affected devices improperly sanitize user input on the telnet command line interface. This could allow an authenticated user to escalate privileges by injecting arbitrary commands executed with root privileges. 

CVE-2022-31808 has been assigned to this vulnerability. A CVSS v3 base score of 7.8 has been assigned. The CVSS vector string is (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H). 

3.3 BACKGROUND

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

3.4 RESEARCHER

Airbus Security 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: 

• SiPass integrated ACC-AP: Update to V2.85.43 or later version 
• SiPass integrated AC5102 (ACC-G2): Update to V2.85.44 or later version 
• SiPass integrated AC5100 (ACC): Currently no fix is planned 
• SiPass integrated AC5200 (ACC-Lite, ACC-4, ACC-8, ACC-16, ACC-32): Currently no fix is planned 
• SiPass integrated Granta-MK3 (ACC-GRANTA): Currently no fix is planned 
• Disable telnet access 
• Set individual passwords for the main accounts provided in the ACC firmware (SIEMENS, OPERATOR) 

As a general security measure, Siemens strongly recommends protecting network access to affected products with appropriate mechanisms. It is advised to follow recommended security practices that run the devices in a protected IT environment.  

For further inquiries on security vulnerabilities in Siemens products and solutions, users should contact the Siemens ProductCERT.  

For more information, see the associated Siemens security advisory SSA-658793 in HTML and CSAF. 

CISA 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 they are not accessible from the Internet.
• Locate control system networks and remote devices behind firewalls and isolate them from business networks.
• When remote access is required, use 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 its 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 at 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.

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 exploits specifically target this vulnerability. This vulnerability is not exploitable remotely.