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AUSCERT External Security Bulletin Redistribution
ESB-2020.3143
Advisory (icsa-20-254-03) HMS Networks Ewon Flexy and Cosy
14 September 2020
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AusCERT Security Bulletin Summary
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Product: HMS Networks Ewon Flexy and Cosy
Publisher: ICS-CERT
Operating System: Network Appliance
Impact/Access: Access Confidential Data -- Existing Account
Resolution: Patch/Upgrade
CVE Names: CVE-2020-16230
Original Bulletin:
https://us-cert.cisa.gov/ics/advisories/icsa-20-254-03
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ICS Advisory (ICSA-20-254-03)
HMS Networks Ewon Flexy and Cosy
Original release date: September 10, 2020
Legal Notice
All information products included in https://us-cert.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://www.us-cert.gov/tlp/ .
1. EXECUTIVE SUMMARY
o CVSS v3 2.3
o ATTENTION: Low skill level to exploit
o Vendor: HMS Networks
o Equipment: Ewon Flexy and Cosy
o Vulnerability: Permissive Cross-domain Policy with Untrusted Domains
2. RISK EVALUATION
Successful exploitation of this vulnerability could allow attackers to retrieve
limited confidential information.
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
The following Ewon products are affected:
o Flexy and Cosy: All versions prior to 14.1
3.2 VULNERABILITY OVERVIEW
3.2.1 PERMISSIVE CROSS-DOMAIN POLICY WITH UNTRUSTED DOMAINS CWE-942
Affected devices use wildcards such as (*) under which domains can request
resources. An attacker with local access and high privileges could inject
scripts into the Cross-origin Resource Sharing (CORS) configuration that could
abuse this vulnerability, allowing the attacker to retrieve limited
confidential information through sniffing.
CVE-2020-16230 has been assigned to this vulnerability. A CVSS v3 base score of
2.3 has been calculated; the CVSS vector string is ( AV:L/AC:L/PR:H/UI:N/S:U/
C:L/I:N/A:N ).
3.3 BACKGROUND
o CRITICAL INFRASTRUCTURE SECTORS: Commercial Facilities, Critical
Manufacturing, Energy, and Water and Wastewater Systems
o COUNTRIES/AREAS DEPLOYED: Worldwide
o COMPANY HEADQUARTERS LOCATION: Sweden
3.4 RESEARCHER
Parth Srivastava of Protiviti India Member Private Limited reported this
vulnerability to HMS Networks.
4. MITIGATIONS
HMS Networks recommends the following mitigations:
o Update firmware to the latest version available.
o Use secure Talk2M cloud solutions to create a VPN tunnel connecting Ewon
devices remotely.
o Do not publicly expose the WAN IP of your devices on the internet.
o Use the WAN firewall, which is built into all Ewon devices.
CISA recommends users take defensive measures to minimize the risk of
exploitation of this vulnerability. Specifically, users should:
o Practice principles of least privilege .
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
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
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. This
vulnerability is not exploitable remotely.
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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