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AUSCERT External Security Bulletin Redistribution
ESB-2021.0474
Advisory (icsa-21-040-03) Siemens SINEMA Server & SINEC NMS
10 February 2021
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AusCERT Security Bulletin Summary
---------------------------------
Product: Siemens SINEMA Server
Siemens SINEC NMS
Publisher: ICS-CERT
Operating System: Network Appliance
Impact/Access: Execute Arbitrary Code/Commands -- Existing Account
Resolution: Patch/Upgrade
CVE Names: CVE-2020-25237
Original Bulletin:
https://us-cert.cisa.gov/ics/advisories/icsa-21-040-03
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ICS Advisory (ICSA-21-040-03)
Siemens SINEMA Server & SINEC NMS
Original release date: February 09, 2021
Legal Notice
All information products included in https://us-cert.cisa.gov/ics are provided
"as is" for informational purposes only. The Department of Homeland Security
(DHS) does not provide any warranties of any kind regarding any information
contained within. DHS does not endorse any commercial product or service,
referenced in this product or otherwise. Further dissemination of this product
is governed by the Traffic Light Protocol (TLP) marking in the header. For more
information about TLP, see https://us-cert.cisa.gov/tlp/ .
1. EXECUTIVE SUMMARY
o CVSS v3 8.8
o ATTENTION: Exploitable remotely/low skill level to exploit
o Vendor: Siemens
o Equipment: SINEMA Server, SINEC NMS
o Vulnerability: Path Traversal
2. RISK EVALUATION
Successful exploitation of this vulnerability could allow arbitrary code
execution on an affected system.
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
The following versions of Siemens products, are affected:
o SINEC NMS: All versions prior to v1.0 SP1 Update 1
o SINEMA Server: All versions prior to v14.0 SP2 Update 2
3.2 VULNERABILITY OVERVIEW
3.2.1 IMPROPER LIMITATION OF A PATHNAME TO A RESTRICTED DIRECTORY ('PATH
TRAVERSAL') CWE-22
When uploading files to an affected system using a zip container, the system
does not correctly check if the relative file path of the extracted files is
still within the intended target directory. An attacker could exploit this
vulnerability to create or overwrite arbitrary files on an affected system.
CVE-2020-25237 has been assigned to this vulnerability. A CVSS v3 base score of
8.8 has been calculated; the CVSS vector string is ( AV:N/AC:L/PR:L/UI:N/S:U/
C:H/I:H/A:H ).
3.3 BACKGROUND
o CRITICAL INFRASTRUCTURE SECTORS: Chemical, Energy, Food and Agriculture,
Water and Wastewater Systems
o COUNTRIES/AREAS DEPLOYED: Worldwide
o COMPANY HEADQUARTERS LOCATION: Germany
3.4 RESEARCHER
rgod, working with Trend Micro's Zero Day Initiative, reported this
vulnerability to CISA.
4. MITIGATIONS
Siemens has published security advisory SSA-156833 that further describes how
this vulnerability affects SINEC NMS and SINEMA Server . Siemens recommends
users update their products to the latest version.
Siemens has identified the following specific workarounds and mitigations users
can apply to reduce risk:
o Restrict access to the affected components to trusted personnel.
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 manual.
Additional information on industrial security by Siemens can be found at:
https://www.siemens.com/industrialsecurity
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
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 this vulnerability.
For any questions related to this report, please contact the CISA at:
Email: CISAservicedesk@cisa.dhs.gov
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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