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AUSCERT External Security Bulletin Redistribution
Advisory (icsa-19-253-05) Siemens SIMATIC TDC CP51M1
11 September 2019
AusCERT Security Bulletin Summary
Product: Siemens SIMATIC TDC CP51M1
Operating System: Windows
Impact/Access: Denial of Service -- Remote/Unauthenticated
CVE Names: CVE-2019-10937
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ICS Advisory (ICSA-19-253-05)
Siemens SIMATIC TDC CP51M1
Original release date: September 10, 2019
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1. EXECUTIVE SUMMARY
o CVSS v3 7.5
o ATTENTION: Exploitable remotely/low skill level to exploit
o Vendor: Siemens
o Equipment: SIMATIC TDC CP51M1
o Vulnerability: Improper Input Validation
2. RISK EVALUATION
Successful exploitation of this vulnerability could create a denial-of-service
condition within UDP communication.
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
The following versions of SIMATIC TDC CP51M1, a multiprocessor automation
system, are affected:
o SIMATIC TDC CP51M1: All versions prior to 1.1.7
3.2 VULNERABILITY OVERVIEW
3.2.1 IMPROPER INPUT VALIDATION CWE-20
An attacker sending a specially crafted UDP packet to the device may affect the
UDP communication, causing a denial-of-service condition.
CVE-2019-10937 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/
o CRITICAL INFRASTRUCTURE SECTORS: Critical Manufacturing
o COUNTRIES/AREAS DEPLOYED: Worldwide
o COMPANY HEADQUARTERS LOCATION: Germany
Siemens reported this vulnerability to CISA.
Siemens recommends users update to Version 1.1.7 or later. Updates can be
obtained at the following link:
Siemens has identified the following specific workarounds and mitigations that
users may apply to reduce the risk:
o Restrict network access to affected devices
o Restrict UDP communication to affected devices
o Do not use UDP communication in the user program if not needed
o Apply cell protection concept and implement 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 (download: https://www.siemens.com/cert/
operational-guidelines-industrial-security ), and follow the recommendations in
the product manuals. Additional information on industrial security by Siemens
can be found at:
For more information, please see Siemens Security Advisory SSA-250618 at the
CISA recommends users take defensive measures to minimize the risk of
exploitation of this vulnerability. Specifically, users should:
o Locate control system networks and remote devices behind firewalls and
isolate them from the business network.
o 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
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.
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