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AUSCERT External Security Bulletin Redistribution
ESB-2021.2300
Advisories (icsa-21-182-04 and icsa-21-182-05) Mitsubishi
Electric Air Conditioning System
2 July 2021
===========================================================================
AusCERT Security Bulletin Summary
---------------------------------
Product: Mitsubishi Electric Air Conditioning System Products
Publisher: ICS-CERT
Operating System: Network Appliance
Impact/Access: Increased Privileges -- Existing Account
Modify Arbitrary Files -- Existing Account
Provide Misleading Information -- Existing Account
Unauthorised Access -- Remote/Unauthenticated
Reduced Security -- Remote/Unauthenticated
Resolution: Patch/Upgrade
CVE Names: CVE-2021-20595 CVE-2021-20593
Original Bulletin:
https://us-cert.cisa.gov/ics/advisories/icsa-21-182-04
https://us-cert.cisa.gov/ics/advisories/icsa-21-182-05
Comment: This bulletin contains two (2) ICS-CERT security advisories.
- --------------------------BEGIN INCLUDED TEXT--------------------
ICS Advisory (ICSA-21-182-04)
Mitsubishi Electric Air Conditioning System
Original release date: July 01, 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 7.1
o ATTENTION: Exploitable remotely
o Vendor: Mitsubishi Electric
o Equipment: Multiple Air Conditioning Systems
o Vulnerability: Incorrect Implementation of Authentication Algorithm
2. RISK EVALUATION
An attacker could exploit this vulnerability by impersonating administrators to
disclose configuration information of the air conditioning system in order to
tamper with operation information and system configuration.
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
Mitsubishi Electric reports this vulnerability affects the following air
conditioning systems:
o Air Conditioning System / Centralized Controllers affected:
G-50A: Version 2.50 to Version 3.35
GB-50A: Version 2.50 to Version 3.35
AG-150A-A: Versions 3.20 and prior
AG-150A-J: Versions 3.20 and prior
GB-50ADA-A: Versions 3.20 and prior
GB-50ADA-J: Versions 3.20 and prior
EB-50GU-A: Versions 7.09 and prior
EB-50GU-J: Versions 7.09 and prior
AE-200A: Versions 7.93 and prior
AE-200E: Versions 7.93 and prior
AE-50A: Versions 7.93 and prior
AE-50E: Versions 7.93 and prior
EW-50A: Versions 7.93 and prior
EW-50E: Versions 7.93 and prior
TE-200A: Versions 7.93 and prior
TE-50A: Versions 7.93 and prior
TW-50A: Versions 7.93 and prior
CMS-RMD-J: Versions 1.30 and prior
o Air Conditioning System / Expansion Controllers are affected:
PAC-YG50ECA: Versions 2.20 and prior
To learn how to determine the version number of equipment, please see
publication number 2021-004 from Mitsubishi Electric.
3.2 VULNERABILITY OVERVIEW
3.2.1 INCORRECT IMPLEMENTATION OF AUTHENTICATION ALGORITHM CWE-303
Web functions of Mitsubishi Electric air conditioning systems have a privilege
escalation vulnerability due to incorrect implementation of the authentication
algorithm. This vulnerability may allow an attacker to impersonate an
administrator and tamper with information (e.g., operation information and
configuration of the air conditioning system).
CVE-2021-20593 has been assigned to this vulnerability. A CVSS v3 base score of
7.1 has been assigned; the CVSS vector string is ( AV:N/AC:H/PR:L/UI:N/S:C/C:L/
I:H/A:N ).
3.3 BACKGROUND
o CRITICAL INFRASTRUCTURE SECTORS: Commercial Facilities
o COUNTRIES/AREAS DEPLOYED: Worldwide
o COMPANY HEADQUARTERS LOCATION: Japan
3.4 RESEARCHER
Chizuru Toyama of TXOne IoT/ICS Security Research Labs, working with Trend
Micro's Zero Day Initiative, reported this vulnerability to CISA.
4. MITIGATIONS
Mitsubishi Electric has created the following versions to address the issue,
and recommends users update to one of the following versions below or newer:
o Air Conditioning System/Centralized Controllers:
G-50A: Version 3.37 or later
GB-50A: Version 3.37 or later
AG-150A-A: Version 3.21 or later
AG-150A-J: Version 3.21 or later
GB-50ADA-A: Version 3.21 or later
GB-50ADA-J: Version 3.21 or later
EB-50GU-A: Version 7.10 or later
EB-50GU-J: Version 7.10 or later
AE-200A: Version 7.95 or later
AE-200E: Version 7.95 or later
AE-50A: Version 7.95 or later
AE-50E: Version 7.95 or later
EW-50A: Version 7.95 or later
EW-50E: Version 7.95 or later
TE-200A: Version 7.95 or later
TE-50A: Version 7.95 or later
TW-50A: Version 7.95 or later
CMS-RMD-J: Version 1.40 or later
o Air Conditioning System / Expansion Controllers:
PAC-YG50ECA: Version 2.21 or later
Mitsubishi Electric recommends users take the following mitigation measures to
minimize the risks associated with this vulnerability:
o Use a VPN router, etc. when connecting the air conditioning system to the
Internet.
o Use an antivirus software computer on systems used to connect conditioning
systems.
o Restrict the access to air conditioning systems from untrusted networks and
hosts.
o Change default usernames and passwords.
Please contact a distributor or Mitsubishi Electric representative for
available updates.
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 its 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. This
vulnerability has a high attack complexity.
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.
- --------------------------------------------------------------------------------
ICS Advisory (ICSA-21-182-05)
Mitsubishi Electric Air Conditioning Systems
Original release date: July 01, 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 9.3
o ATTENTION: Exploitable remotely/low attack complexity
o Vendor: Mitsubishi Electric
o Equipment: Multiple Air Conditioning Systems
o Vulnerability: Improper Restriction of XML External Entity Reference
2. RISK EVALUATION
Successful exploitation of this vulnerability may allow an attacker to disclose
some of the data in the air conditioning system or cause a denial-of-service
condition.
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
Mitsubishi Electric reports this vulnerability affects the following air
conditioning systems:
o Air Conditioning System/Centralized Controllers:
G-50A: Versions 3.35 and prior
GB-50A: Versions 3.35 and prior
GB-24A: Versions 9.11 and prior
AG-150A-A: Versions 3.20 and prior
AG-150A-J: Versions 3.20 and prior
GB-50ADA-A: Versions 3.20 and prior
GB-50ADA-J: Versions 3.20 and prior
EB-50GU-A: Versions 7.09 and prior
EB-50GU-J: Versions 7.09 and prior
AE-200A: Versions 7.93 and prior
AE-200E: Versions 7.93 and prior
AE-50A: Versions 7.93 and prior
AE-50E: Versions 7.93 and prior
EW-50A: Versions 7.93 and prior
EW-50E: Versions 7.93 and prior
TE-200A: Versions 7.93 and prior
TE-50A: Versions 7.93 and prior
TW-50A: Versions 7.93 and prior
CMS-RMD-J: Versions 1.30 and prior
o Air Conditioning System/Expansion Controllers:
PAC-YG50ECA: Versions 2.20 and prior
o Air Conditioning System/BM adapter:
BAC-HD150: Versions 2.21 and prior
To learn how to determine the version number of equipment, please see
publication number 2021-005 from Mitsubishi Electric.
3.2 VULNERABILITY OVERVIEW
3.2.1 IMPROPER RESTRICTION OF XML EXTERNAL ENTITY REFERENCE CWE-611
The affected product does not properly restrict XML external entity references.
CVE-2021-20595 has been assigned to this vulnerability. A CVSS v3 base score of
9.3 has been calculated; the CVSS vector string is ( AV:N/AC:L/PR:N/UI:N/S:C/
C:L/I:N/A:H ).
3.3 BACKGROUND
o CRITICAL INFRASTRUCTURE SECTORS: Commercial Facilities
o COUNTRIES/AREAS DEPLOYED: Worldwide
o COMPANY HEADQUARTERS LOCATION: Japan
3.4 RESEARCHER
Howard McGreehan of Aon's Cyber Solutions reported this vulnerability to
Mitsubishi Electric.
4. MITIGATIONS
Mitsubishi Electric has created the following versions to address the issue,
and recommends users update to one of the following versions below or newer:
o Air Conditioning System/Centralized Controllers:
G-50A: Version 3.37 or later
GB-50A: Version 3.37 or later
GB-24A: Version 9.12 or later
AG-150A-A: Version 3.21 or later
AG-150A-J: Version 3.21 or later
GB-50ADA-A: Version 3.21 or later
GB-50ADA-J: Version 3.21 or later
EB-50GU-A: Version 7.10 or later
EB-50GU-J: Version 7.10 or later
AE-200A: Version 7.95 or later
AE-200E: Version 7.95 or later
AE-50A: Version 7.95 or later
AE-50E: Version 7.95 or later
EW-50A: Version 7.95 or later
EW-50E: Version 7.95 or later
TE-200A: Version 7.95 or later
TE-50A: Version 7.95 or later
TW-50A: Version 7.95 or later
CMS-RMD-J: Version 1.40 or later
o Air Conditioning System/Expansion Controllers:
PAC-YG50ECA: Version 2.21 or later
o Air Conditioning System/BM adapter:
BAC-HD150: Version 2.22 or later
Mitsubishi Electric recommends taking the following mitigation measures to
minimize the risk of exploiting this vulnerability:
o Use a VPN router, etc. when you connect air conditioning systems to the
Internet.
o Use anti-virus software on computers connected to air conditioning systems.
o Restrict the access to air conditioning systems from untrusted networks and
hosts.
Please refer to the Mitsubishi Electric website for additional details about
this issue.
CISA recommends users take defensive measures to minimize the risk of
exploitation of this vulnerability. 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.
CISA also recommends users take the following measures to protect themselves
from social engineering attacks:
o Do not click web links or open unsolicited attachments in email messages.
o Refer to Recognizing and Avoiding Email Scams for more information on
avoiding email scams.
o Refer to Avoiding Social Engineering and Phishing Attacks for more
information on social engineering attacks.
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.
- --------------------------END INCLUDED TEXT--------------------
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