ICS Advisory (ICSA-20-042-03)

Siemens SIMATIC CP 1543-1

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1. EXECUTIVE SUMMARY

  • CVSS v3 9.8
  • ATTENTION: Exploitable remotely/low skill level to exploit
  • Vendor: Siemens
  • Equipment: SIMATIC CP 1543-1
  • Vulnerabilities: Improper Access Control, Loop with Unreachable Exit Condition

2. RISK EVALUATION

Successful exploitation of these vulnerabilities could allow for remote code execution and information disclosure without authentication, or unauthenticated denial of service.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following versions of Siemens SIMATIC CP 1543-1, including SIPLUS NET variants, are affected:

  • All versions starting at 2.0 and prior to 2.2

3.2 VULNERABILITY OVERVIEW

3.2.1    IMPROPER ACCESS CONTROL CWE-284

An arbitrary file copy vulnerability in mod_copy of the embedded FTP server allows for remote code execution and information disclosure without authentication.

CVE-2019-12815 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).

3.2.2    LOOP WITH UNREACHABLE EXIT CONDITION CWE-835

Incorrect handling of overly long commands in the embedded FTP server allow an attacker to cause a denial-of-service condition by entering an infinite loop.

CVE-2019-18217 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).

3.3 BACKGROUND

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

3.4 RESEARCHER

Siemens reported these vulnerabilities to CISA.

4. MITIGATIONS

The latest update for SIMATIC CP 1543-1 contains fixes for the vulnerabilities within its embedded ProFTPD FPT server. Siemens recommends updating SIMATIC CP 1543-1 modules to Version 2.2

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

  • Disable the embedded FTP server. The server is deactivated in the default configuration.
  • Limit access to Port 21/TCP to trusted IP addresses.

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 on the vulnerabilities and detailed mitigation instructions, please see Siemens security advisory SSA-940889

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.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://us-cert.cisa.gov/ics 
or incident reporting:  https://us-cert.cisa.gov/report

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