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AUSCERT External Security Bulletin Redistribution
Advisory (icsa-21-012-05) Siemens SCALANCE X Products
13 January 2021
AusCERT Security Bulletin Summary
Product: Siemens SCALANCE X Products
Operating System: Network Appliance
Impact/Access: Denial of Service -- Remote/Unauthenticated
CVE Names: CVE-2020-25226 CVE-2020-15800 CVE-2020-15799
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ICS Advisory (ICSA-21-012-05
Siemens SCALANCE X Products
Original release date: January 12, 2021
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1. EXECUTIVE SUMMARY
o CVSS v3 9.8
o ATTENTION: Exploitable remotely/low skill level to exploit
o Vendor: Siemens
o Equipment: SCALANCE X Products
o Vulnerabilities: Missing Authentication for Critical Function, Heap-based
2. RISK EVALUATION
Successful exploitation of these vulnerabilities could cause denial-of-service
conditions and further impact the system through heap and buffer overflows.
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
Siemens reports that these vulnerabilities affect the following SCALANCE X
o SCALANCE X-200 switch family (incl. SIPLUS NET variants): All versions
o SCALANCE X-200IRT switch family (incl. SIPLUS NET variants): All versions
o SCALANCE X-300 switch family (incl. X408 and SIPLUS NET variants): All
versions prior to v4.1.0
3.2 VULNERABILITY OVERVIEW
3.2.1 MISSING AUTHENTICATION FOR CRITICAL FUNCTION CWE-306
This vulnerability could allow an unauthenticated attacker to reboot the device
over the network by using special URLs from integrated web server of the
CVE-2020-15799 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/
3.2.2 HEAP-BASED BUFFER OVERFLOW CWE-122
The webserver of the affected devices contains a vulnerability that may lead to
a heap-overflow condition. An attacker could cause this condition on the
webserver by sending specially crafted requests. This could stop the webserver
CVE-2020-15800 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/
3.2.3 HEAP-BASED BUFFER OVERFLOW CWE-122
The web server of the affected devices contains a vulnerability that may lead
to a buffer-overflow condition. An attacker could cause this condition on the
webserver by sending a specially crafted request. The webserver could stop and
CVE-2020-25226 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/
o CRITICAL INFRASTRUCTURE SECTORS: Critical Manufacturing
o COUNTRIES/AREAS DEPLOYED: Worldwide
o COMPANY HEADQUARTERS LOCATION: Germany
Siemens reported these vulnerabilities to CISA.
Siemens has released updates for several affected products and recommends
updating to the latest version(s). Siemens recommends countermeasures where
fixes are not currently available.
o SCALANCE X-300 switch family: Update to v4.1.0 or later
Siemens has identified the following specific workarounds and mitigations users
can apply to reduce the risk:
o Limit network traffic of web servers of SCALANCE X switches to trusted
connections by firewall rules (Port 443/TCP).
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 the Siemens operational guidelines for Industrial Security and
following the recommendations in the product manuals.
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 these vulnerabilities.
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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