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AUSCERT External Security Bulletin Redistribution
Advisory (icsa-20-315-04) SIMATIC S7-300 CPUs and SINUMERIK Controller
13 November 2020
AusCERT Security Bulletin Summary
Product: SIMATIC S7-300 CPUs
Operating System: Network Appliance
Impact/Access: Denial of Service -- Remote/Unauthenticated
CVE Names: CVE-2020-15783
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ICS Advisory (ICSA-20-315-04)
SIMATIC S7-300 CPUs and SINUMERIK Controller
Original release date: November 10, 2020
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1. EXECUTIVE SUMMARY
o CVSS v3 5.9
o ATTENTION: Exploitable remotely
o Vendor: Siemens
o Equipment: SIMATIC S7-300 CPUs and SINUMERIK Controller
o Vulnerability: Uncontrolled Resource Consumption
2. RISK EVALUATION
Successful exploitation of this vulnerability could allow an attacker to cause
a denial-of-service condition.
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
Siemens reports the vulnerability affects the following products:
o SIMATIC S7-300 CPU family (incl. related ET200 CPUs and SIPLUS variants):
o SINUMERIK 840D sl: All versions
3.2 VULNERABILITY OVERVIEW
3.2.1 UNCONTROLLED RESOURCE CONSUMPTION CWE-400
An attacker may send multiple specially crafted packets to the affected
devices, which may cause a denial-of-service condition. A cold restart is
required to recover the service.
CVE-2020-15783 has been assigned to this vulnerability. A CVSS v3 base score of
5.9 has been calculated; the CVSS vector string is ( AV:N/AC:H/PR:N/UI:N/S:U/
o CRITICAL INFRASTRUCTURE SECTORS: Chemical, Critical Manufacturing, Food and
o COUNTRIES/AREAS DEPLOYED: Worldwide
o COMPANY HEADQUARTERS LOCATION: Germany
WangFangLi from Beijing Winicssec Technology CO reported this vulnerability to
Siemens is preparing updates and recommends users protect network access to
Port 102/TCP of affected devices.
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:
For additional information, please refer to Siemens Security Advisory
CISA recommends users take defensive measures to minimize the risk of
exploitation of this vulnerability. Specifically, users should:
o Minimize network exposure for all control system devices and/or systems,
and ensure that they are not accessible from the Internet .
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.cisa.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.cisa.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. High skill
level is needed to exploit.
For any questions related to this report, please contact the CISA at:
Toll Free: 1-888-282-0870
CISA continuously strives to improve its products and services. You can help by
choosing one of the links below to provide feedback about this product.
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