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AUSCERT External Security Bulletin Redistribution
Advisory (icsa-21-336-01) Schneider Electric SESU
3 December 2021
AusCERT Security Bulletin Summary
Product: Schneider Electric SESU
Operating System: Network Appliance
Impact/Access: Reduced Security -- Existing Account
CVE Names: CVE-2021-22799
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ICS Advisory (ICSA-21-336-01)
Schneider Electric SESU
Original release date: December 02, 2021
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1. EXECUTIVE SUMMARY
o CVSS v3 3.8
o ATTENTION: Low attack complexity
o Vendor: Schneider Electric
o Equipment: Schneider Electric Software Update (SESU)
o Vulnerability: Insufficient Entropy
2. RISK EVALUATION
Successful exploitation of this vulnerability could cause unintended connection
from an internal network to an external network.
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
The following versions of Schneider Electric Software Update, are affected:
o Schneider Electric Software Update: v2.3.0 through v2.5.1
Schneider Electric Software Update is used by the following products:
o EcoStruxure Augmented Operator Advisor
o EcoStruxure Control Expert (formerly known as Unity Pro)
o EcoStruxure Process Expert (formerly known as EcoStruxure Hybrid
Distributed Control System)
o EcoStruxure Machine Expert (formerly known as SoMachine or SoMachine
o EcoStruxure Machine Expert Basic
o EcoStruxure Operator Terminal Expert
o EcoStruxure Plant Builder
o EcoStruxure Power Design
o EcoStruxure Automation Expert
o EcoStruxure Automation Maintenance Expert
o Eurotherm Data Reviewer
o Eurotherm iTools
o eXLhoist Configuration Software
o Schneider Electric Floating License Manager
o Schneider Electric License Manager
o Harmony XB5SSoft
o Versatile Software BLUE
o Vijeo Designer
o OsiSense XX Configuration Software
o Zelio Soft 2
Note: This vulnerability affects all products listed above, but this is not a
complete list of products. Some of the products might not deliver SESU as part
of the product package; however, SESU can be downloaded and used to manage
product updates. It may also be possible more components for one product are
listed in the "SESU Managed Products" dialog for update.
3.2 VULNERABILITY OVERVIEW
3.2.1 INSUFFICIENT ENTROPY CWE-331
An insufficient entropy vulnerability exists, which could cause unintended
connection from an internal network to an external network when an attacker
manages to decrypt the SESU proxy password from the registry.
CVE-2021-22799 has been assigned to this vulnerability. A CVSS v3 base score of
3.8 has been calculated; the CVSS vector string is ( AV:L/AC:L/PR:L/UI:N/S:C/
o CRITICAL INFRASTRUCTURE SECTORS: Commercial Facilities, Critical
o COUNTRIES/AREAS DEPLOYED: Worldwide
o COMPANY HEADQUARTERS LOCATION: France
Nozomi Networks reported this vulnerability to CISA.
Schneider Electric recommends the following:
o If SESU is installed (assuming SESU is configured as "managed product"
inside the SESU application) it will indicate a security update is
available. Click to download and install the new SESU version.
o If SESU is not installed, download SESU (automatic download) and follow the
Schneider Electric strongly recommends observing the following industry
cybersecurity best practices:
o Locate control and safety system networks and remote devices behind
firewalls and isolate them from the business network.
o Install physical controls so no unauthorized personnel can access your
industrial control and safety systems, components, peripheral equipment,
o Place all controllers in locked cabinets and never leave them in the
o Never connect programming software to any network other than the network
intended for that device.
o Scan all methods of mobile data exchange with the isolated network such as
CDs, USB drives, etc. before use in the terminals or any node connected to
o Never allow mobile devices that have connected to any other network besides
the intended network to connect to the safety or control networks without
o Minimize network exposure for all control system devices and systems and
ensure they are not accessible from the Internet.
o When remote access is required, use secure methods, such as virtual private
networks (VPNs), recognizing VPNs may have vulnerabilities and should be
updated to the most current version available. Also recognize VPN are only
as secure as the connected devices.
See Schneider Electric Security Notification SEVD-2021-313-02 for more
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. This
vulnerability is not exploitable remotely.
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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