Siemens SIMATIC Process Historian

1. EXECUTIVE SUMMARY

• CVSS v3 9.8
• ATTENTION: Exploitable remotely/low attack complexity
• Vendor: Siemens
• Equipment: SIMATIC Process Historian
• Vulnerability: Missing Authentication for Critical Function

2. RISK EVALUATION

Successful exploitation of this vulnerability could enable the execution of admin operations on the database.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following versions of SIMATIC Process Historian, a long-term archive system, are affected:

• SIMATIC Process Historian 2013 and earlier: All versions
• SIMATIC Process Historian 2014: All versions prior to SP3 Update 6
• SIMATIC Process Historian 2019: All versions
• SIMATIC Process Historian 2020: All versions

3.2 VULNERABILITY OVERVIEW

3.2.1    MISSING AUTHENTICATION FOR CRITICAL FUNCTION CWE-306

An interface in the software used for critical functionalities lacks authentication, which could allow a malicious attacker to insert, modify, or delete data.

CVE-2021-27395 has been assigned to this vulnerability. A CVSS v3 base score of 9.8 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).

3.3 BACKGROUND

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

3.4 RESEARCHER

Siemens reported this vulnerability to CISA.

4. MITIGATIONS

Siemens has released an update for the following affected products:

• SIMATIC Process Historian 2013 and earlier, all versions: See general Siemens recommendations below or upgrade to a newer SIMATIC Process Historian version.
• SIMATIC Process Historian 2014, all versions prior to SP3 Update 6: Update to SP3 Update 6 or later version.

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

• Deactivate following incoming rules in the local Windows firewall:
  • PH Redundancy Services
  • PH Wcf MessageQueue Service (RedundancyMaintenanceService)
  • PH Wcf MessageQueue Service (SqlMirroringSetup)
  • PH Wcf MessageQueue Service (MaintenanceService)
  • PH SQL-Server Mirroring Port (UDP)
  • PH SQL-Server Mirroring Port (TCP)
• In case SIMATIC Process Historian is used as a redundant system, restrict remote IP addresses in the firewall rules to allow only access for the Master, the Standby, and the Mirror server.

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

For further inquiries on security vulnerabilities in Siemens products and solutions, please contact Siemens.

Additional information on Industrial Security by Siemens can be found at: https://www.siemens.com/industrialsecurity

For more information about this issue, see Siemens Security Advisory SSA-766247

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 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.

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 us-cert.cisa.gov. 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 webpage on us-cert.cisa.gov 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 CISA for tracking and correlation against other incidents.

No known public exploits specifically target this vulnerability.