ICS Advisory (ICSA-19-344-03)

Siemens RUGGEDCOM ROS

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1. EXECUTIVE SUMMARY

  • CVSS v3 7.8
  • ATTENTION: Low skill level to exploit
  • Vendor: Siemens
  • Equipment: RUGGEDCOM ROS
  • Vulnerabilities: Improper Restriction of Operations within the Bounds of a Memory Buffer, Resource Management Errors

2. RISK EVALUATION

Successful exploitation of these vulnerabilities could allow a denial-of-service condition or arbitrary code execution.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following versions of RUGGEDCOM ROS, an ethernet switch, are affected:

  • RMC8388: all versions
  • RSG2488: all versions
  • RSG920P: all versions
  • RSG9xx R/C: all versions
  • RSL910: all versions
  • RST2228: all versions

Some of these devices are only affected by one of these vulnerabilities, please see SSA-618620 for details.

3.2 VULNERABILITY OVERVIEW

3.2.1 IMPROPER RESTRICTION OF OPERATIONS WITHIN THE BOUNDS OF A MEMORY BUFFER CWE-119

The embedded boot loader has a locally exploitable buffer overflow via a crafted kernel image because the filesystem loading is mishandled.

CVE-2018-18440 has been assigned to this vulnerability. A CVSS v3 base score of 7.8 has been calculated; the CVSS vector string is (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H).

3.2.2 RESOURCE MANAGEMENT ERRORS CWE-399

The embedded boot loader has a physically exploitable vulnerability. A crafted self-referential DOS partition table will cause the bootloader to infinitely recurse, causing the stack to grow infinitely and eventually crash.

CVE-2019-13103 has been assigned to this vulnerability. A CVSS v3 base score of 4.6 has been calculated; the CVSS vector string is (AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

3.3 BACKGROUND

  • CRITICAL INFRASTRUCTURE SECTORS: Energy, Healthcare and Public Health, Transportation Systems
  • COUNTRIES/AREAS DEPLOYED: Worldwide
  • COMPANY HEADQUARTERS LOCATION: Germany

3.4 RESEARCHER

Siemens reported these vulnerabilities to CISA.

4. MITIGATIONS

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

  • CVE-2018-18440: Disable boot interface access during boot up via the ‘bootoption.txt’ file parameter ‘Security = yes’.
  • CVE-2019-13103: Disable access to the removable media via ‘bootoption.txt’ file parameter ‘Disableautoaccessremovable = yes’. Note that this vulnerability only applies to RUGGEDCOM ROS, if the device boots from removable media.

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 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 this vulnerability and more detailed mitigation instructions, please see Siemens security advisory SSA-618620 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:

  • Restrict access to devices following a least privilege principle.
  • Implement physical security controls to mitigate unauthorized physical access. 

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. These vulnerabilities are not exploitable remotely.


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