ICS Advisory (ICSA-19-253-03)

Siemens Industrial Products (Update A)

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1. EXECUTIVE SUMMARY

  • CVSS v3 7.5
  • ATTENTION: Exploitable remotely/low skill level to exploit
  • Vendor: Siemens
  • Equipment: Industrial Products
  • Vulnerabilities: Integer Overflow or Wraparound, Uncontrolled Resource Consumption

2. UPDATE INFORMATION

This updated advisory is a follow-up to the original advisory titled ICSA-19-253-03 Siemens Industrial Products that was published September 10, 2019, on the ICS webpage on us-cert.gov.

3. RISK EVALUATION

Successful exploitation of these vulnerabilities could cause denial-of-service condition.

4. TECHNICAL DETAILS

4.1 AFFECTED PRODUCTS

Siemens reports the vulnerabilities affect the following industrial products:

  • CM 1542-1: All versions
  • CP 1242-7: All versions
  • CP 1243-1: All versions
  • CP 1243-7 LTE EU: All versions
  • CP 1243-7 LTE US: All versions
  • CP 1243-8 IRC: All versions
  • CP 1542SP-1: All versions
  • CP 1542SP-1 IRC: All versions•    CP 1543-1: All versions
  • CP 1543SP-1: All versions
  • CloudConnect 712: All versions prior to 1.1.5
  • ROX II: All versions (Only vulnerable to CVE-2019-11479)
  • RUGGEDCOM RM1224: All versions
  • S7-1500 CPU 1518(F)-4 PN/DP MFP: All versions
  • SCALANCE M800: All versions
  • SCALANCE M875: All versions
  • SCALANCE S615: All versions
  • SCALANCE SC-600: All versions prior to 2.0.1
  • SCALANCE W-700 (IEEE 802.11n): All versions
  • SCALANCE W1700: All versions
  • SCALANCE WLC711: All versions
  • SCALANCE WLC712: All versions
  • SIMATIC ITC1500: All versions
  • SIMATIC ITC1500 PRO: All versions
  • SIMATIC ITC1900: All versions
  • SIMATIC ITC1900 PRO: All versions
  • SIMATIC ITC2200: All versions
  • SIMATIC ITC2200 PRO: All versions
  • SIMATIC MV500: All versions
  • SIMATIC RF166C: All versions
  • SIMATIC RF185C: All versions
  • SIMATIC RF186C: All versions
  • SIMATIC RF186CI: All versions
  • SIMATIC RF188C: All versions
  • SIMATIC RF188CI: All versions
  • SIMATIC RF600R: All versions
  • SIMATIC Teleserver Adapter IE Advanced: All versions
  • SIMATIC Teleserver Adapter IE Basic: All versions
  • SINEMA Remote Connect Server: All versions prior to 2.0 SP1

--------- Begin Update A Part 1 of 2 ---------

  • SINUMERIK 808D: All versions prior to 4.92
  • SINUMERIK 828D: All versions prior to 4.8 SP5
  • SINUMERIK 840D sl: All versions prior to 4.8 SP5

--------- End Update A Part 1 of 2 ---------

  • TIM 1531 IRC: All versions

4.2 VULNERABILITY OVERVIEW

4.2.1    INTEGER OVERFLOW OR WRAPAROUND CWE-190

The kernel is affected by an integer overflow when handling TCP Selective Acknowledgements, which could allow a remote attacker to cause a denial-of-service condition.

CVE-2019-11477 has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

4.2.2    UNCONTROLLED RESOURCE CONSUMPTION CWE-400

A remote attacker sending specially crafted TCP Selective Acknowledgment (SACK) sequences may cause a denial-of-service condition.

CVE-2019-11478 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).

4.2.3    UNCONTROLLED RESOURCE CONSUMPTION CWE-400

An attacker may exploit a vulnerability in the TCP retransmission queue implementation kernel when handling TCP Selective Acknowledgements (SACK) to cause a denial-of-service condition.

CVE-2019-11479 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: Chemical, Critical Manufacturing, Energy, Food and Agriculture, Water and Wastewater Systems
  • COUNTRIES/AREAS DEPLOYED: Worldwide
  • COMPANY HEADQUARTERS LOCATION: Germany

4.4 RESEARCHER

Siemens reported theses vulnerabilities to CISA.

5. MITIGATIONS

Siemens recommends users follow the specific workarounds and mitigations below. Siemens has also released fixes for the following products:

--------- Begin Update A Part 2 of 2 ---------

  • SINUMERIK 808D: Update to v4.92. The update can be obtained from a Siemens representative or via Siemens customer service.
  • SINUMERIK 828D/840D sl: Update to v4.8 SP5. The update can be obtained from a Siemens representative or via Siemens customer service.

--------- End Update A Part 2 of 2 ---------

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

  • Restrict network access to affected devices
  • Apply defense-in-depth

As a general security measure, Siemens strongly recommends users protect network access to devices with appropriate mechanisms. In order to operate the devices in a protected IT environment, Siemens recommends users configure the environment according to Siemens’ operational guidelines for industrial security, and follow 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, please see Siemens Security Advisory SSA-462066 at the following location:
http://www.siemens.com/cert/advisories

CISA recommends users take defensive measures to minimize the risk of exploitation of these vulnerabilities. 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.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.


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