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AUSCERT External Security Bulletin Redistribution
Advisory (icsa-21-082-02) GE MU320E
24 March 2021
AusCERT Security Bulletin Summary
Product: GE MU320E
Operating System: Network Appliance
Impact/Access: Root Compromise -- Remote/Unauthenticated
Increased Privileges -- Existing Account
Reduced Security -- Existing Account
CVE Names: CVE-2021-27452 CVE-2021-27450 CVE-2021-27448
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ICS Advisory (ICSA-21-082-02)
Original release date: March 23, 2021
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
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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 9.8
o ATTENTION: Exploitable remotely/low skill level to exploit
o Vendor: GE
o Equipment: MU320E
o Vulnerabilities: Use of Hard-coded Password, Execution with Unnecessary
Privileges, Inadequate Encryption Strength
2. RISK EVALUATION
Successful exploitation of these vulnerabilities could allow an attacker to
escalate unnecessary privileges and use hard-coded credentials to take control
of the device.
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
The following firmware versions of MU320E are affected:
o All firmware versions prior to v04A00.1
3.2 VULNERABILITY OVERVIEW
3.2.1 USE OF HARD-CODED PASSWORD CWE-259
The software contains a hard-coded password that could allow an attacker to
take control of the merging unit using these hard-coded credentials.
CVE-2021-27452 has been assigned to this vulnerability. A CVSS v3 base score of
9.8 has been assigned; the CVSS vector string is ( AV:N/AC:L/PR:N/UI:N/S:U/C:H/
3.2.2 EXECUTION WITH UNNECESSARY PRIVILEGES CWE-250
A miscommunication in the file system allows adversaries with access to the
MU320E to escalate privileges.
CVE-2021-27448 has been assigned to this vulnerability. A CVSS v3 base score of
7.8 has been assigned; the CVSS vector string is ( AV:L/AC:L/PR:L/UI:N/S:U/C:H/
3.2.3 INADEQUATE ENCRYPTION STRENGTH CWE-326
SSH server configuration file does not implement some best practices. This
could lead to a weakening of the SSH protocol strength, which could lead to
additional misconfiguration or be leveraged as part of a larger attack.
CVE-2021-27450 has been assigned to this vulnerability. A CVSS v3 base score of
3.8 has been assigned; the CVSS vector string is ( AV:L/AC:H/PR:H/UI:R/S:U/C:L/
o CRITICAL INFRASTRUCTURE SECTORS: Multiple
o COUNTRIES/AREAS DEPLOYED: Worldwide
o COMPANY HEADQUARTERS LOCATION: United States
Tom Westenberg of Thales UK reported these vulnerabilities to GE.
GE recommends MU320E users upgrade to firmware v04A00.1 or higher to mitigate
Instructions on how to upgrade the MU320E firmware and verify its installation
are available in the product user's manual.
See GE publication number: GES-2021-003 for more information.
GE recommends MU320E devices be protected using network defense-in-depth
practices. This includes, but is not limited to, placing MU320E devices inside
the control system network security perimeter, and having access controls,
monitoring (such as an Intrusion Detection System), and other mitigating
technologies in place. Many electric utilities have deployed cyber security
solutions in accordance with the NERC-CIP implementation requirements. Please
refer to the product secure deployment guide.
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 VPNs may have vulnerabilities and should be
updated to the most current version available. Also recognize 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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