ICS Advisory (ICSA-20-196-05)

Siemens UMC Stack (Update B)

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1. EXECUTIVE SUMMARY

  • CVSS v3 6.7
  • ATTENTION: Exploitable remotely/low skill level to exploit
  • Vendor: Siemens
  • Equipment: UMC Stack
  • Vulnerabilities: Unquoted Search Path or Element, Uncontrolled Resource Consumption, Improper Input Validation

2. UPDATE INFORMATION

This updated advisory is a follow-up to the advisory update titled ICSA-20-196-05 Siemens UMC Stack (Update A) that was published August 11, 2020, to the ICS webpage on us-cert.gov.

3. RISK EVALUATION

Successful exploitation of these vulnerabilities could allow an attacker to cause a partial denial-of-service condition on the UMC component of the affected devices under certain circumstances. This could also allow an attacker to locally escalate privileges from a user with administrative privileges to execute code with SYSTEM level privileges.

4. TECHNICAL DETAILS

4.1 AFFECTED PRODUCTS

Siemens reports that some of the vulnerabilities affect the following UMC components. For a complete list of which specific vulnerabilities affect each of these products, please see Siemens security advisory SSA-841348:

  • Opcenter Execution Discrete: All versions prior to v3.2
  • Opcenter Execution Foundation: All versions prior to v3.2
  • Opcenter Execution Process: All versions prior to v3.2
  • Opcenter Intelligence: All versions
  • Opcenter Quality: All versions prior to v11.3
  • Opcenter RD&L: v8.0
  • SIMATIC IT LMS: All versions
  • SIMATIC IT Production Suite: All versions
  • SIMATIC Notifier Server for Windows: All versions

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  • SIMATIC STEP 7 (TIA Portal) v15: All versions prior to v15.1 update 5

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  • SIMATIC PCS neo: All versions prior to v3.0 SP1
  • SIMATIC STEP 7 (TIA Portal) v16: All versions prior to v16 Update 2
  • SIMOCODE ES: All versions
  • Soft Starter ES: All versions

4.2 VULNERABILITY OVERVIEW

4.2.1    UNQUOTED SEARCH PATH OR ELEMENT CWE-428

A component within the affected application calls a helper binary with SYSTEM privileges during startup while the call path is not quoted.

CVE-2020-7581 has been assigned to this vulnerability. A CVSS v3 base score of 6.7 has been calculated; the CVSS vector string is (AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H).

4.2.2    UNCONTROLLED RESOURCE CONSUMPTION CWE-400

Sending multiple specially crafted packets to the affected service could cause a partially remote denial of service, which would cause the service to restart itself. 

CVE-2020-7587 has been assigned to this vulnerability. A CVSS v3 base score of 6.5 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L).

4.2.3    IMPROPER INPUT VALIDATION CWE-20

Sending a specially crafted packet to the affected service could cause a partially remote denial of service, which would cause the service to restart itself. 

CVE-2020-7588 has been assigned to this vulnerability. A CVSS v3 base score of 5.3 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L).

4.3 BACKGROUND

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

4.4 RESEARCHER

Victor Fidalgo of INCIBE and Reid Wightman of Dragos reported these vulnerabilities to Siemens.

5. MITIGATIONS

Siemens recommends users upgrade affected products if upgrade are available for those products:

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For products that do not have an update, Siemens has identified the following specific workarounds and mitigations customers can apply to reduce the risk:

  • Run the software on systems within trusted networks
  • For CVE-2020-7581, ensure there is no executable at the following locations:
    • C:\Program.exe
    • C:\Program Files\Common.exe
    • C:\Program Files\Common Files\Siemens\Automation\Simatic.exe

As a general security measure, Siemens strongly 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 the recommendations in the product manuals.

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

For more information on these vulnerabilities and associated software updates, please see Siemens security advisory SSA-841348

CISA recommends users take the following measures to protect themselves from social engineering attacks: 

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

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.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.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 these vulnerabilities.


Contact Information

For any questions related to this report, please contact the CISA at:

Email: CISAservicedesk@cisa.dhs.gov
Toll Free: 1-888-282-0870

For industrial control systems cybersecurity information:  https://www.us-cert.gov/ics 
or incident reporting:  https://www.us-cert.gov/report

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