6.4 Medium
CVSS2
Attack Vector
NETWORK
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
NONE
AV:N/AC:L/Au:N/C:P/I:P/A:N
9.1 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
7.4 High
AI Score
Confidence
High
0.004 Low
EPSS
Percentile
73.9%
Successful exploitation of these vulnerabilities could allow a remote attacker unauthorized access to legitimate usernames, CPU module access, or the ability to deny access to legitimate users.
Mitsubishi Electric reports these vulnerabilities affect the following MELSEC products. Users may use the manual (MELSEC iQ-R Module Configuration Manual “Appendix 1 Checking Production Information and Firmware Version”) to learn how to check the firmware version:
A remote attacker can leverage a brute-force attack to acquire legitimate usernames registered in the module.
CVE-2021-20594 has been assigned to this vulnerability. A CVSS v3.1 base score of 5.9 has been calculated; the CVSS vector string is (AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N).
A CVSS v4 score has also been calculated for CVE-2021-20594. A base score of 8.2 has been calculated; the CVSS vector string is (CVSS4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N).
A remote attacker could obtain unprotected credentials by sniffing network traffic.
CVE-2021-20597 has been assigned to this vulnerability. A CVSS v3.1 base score of 7.4 has been calculated; the CVSS vector string is (AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N).
A CVSS v4 score has also been calculated for CVE-2021-20597. A base score of 9.1 has been calculated; the CVSS vector string is (CVSS4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N).
A remote attacker could lock out a legitimate user by continually attempting to login with a known username and incorrect passwords.
CVE-2021-20598 has been assigned to this vulnerability. A CVSS v3.1 base score of 3.7 has been calculated; the CVSS vector string is (AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L).
A CVSS v4 score has also been calculated for CVE-2021-20598. A base score of 6.3 has been calculated; the CVSS vector string is (CVSS4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N).
Ivan Speziale of Nozomi Networks Labs reported these vulnerabilities to CISA.
Users of the affected products and versions may take measures through mitigations and workarounds. Mitsubishi Electric has released the fixed versions for CVE-2021-20594 and CVE-2021-20597 as shown below, but updating the product to the fixed version is not available.
Mitsubishi Electric recommends users take the following mitigation measures to minimize the risk of exploiting these vulnerabilities:
Additional information about these vulnerabilities or Mitsubishi Electric’s compensating control is available by contacting a Mitsubishi Electric representative.
Users should refer to Mitsubishi Electric advisories 2021-008, 2021-009, and 2021-010 for further details.
CISA recommends users take defensive measures to minimize the risk of exploitation of these vulnerabilities. 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 cisa.gov/ics. Several CISA products detailing cyber defense best practices are available for reading and download, including Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies.
CISA encourages organizations to implement recommended cybersecurity strategies for proactive defense of ICS assets.
Additional mitigation guidance and recommended practices are publicly available on the ICS webpage at cisa.gov/ics in the technical information paper, ICS-TIP-12-146-01B–Targeted Cyber Intrusion Detection and Mitigation Strategies.
Organizations observing suspected malicious activity should follow established internal procedures and report findings to CISA for tracking and correlation against other incidents.
No known public exploitation specifically targeting this these vulnerabilities has been reported to CISA at this time.
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-20594
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-20594
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-20597
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-20597
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-20597
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-20598
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-20598
cwe.mitre.org/data/definitions/200.html
cwe.mitre.org/data/definitions/522.html
cwe.mitre.org/data/definitions/645.html
github.com/cisagov/CSAF
public.govdelivery.com/accounts/USDHSCISA/subscriber/new?topic_id=USDHSCISA_138
twitter.com/CISAgov
twitter.com/intent/tweet?text=Mitsubishi%20Electric%20MELSEC%20iQ-R%20Series%20%28Update%20B%29+https://www.cisa.gov/news-events/ics-advisories/icsa-21-250-01
us-cert.cisa.gov/sites/default/files/recommended_practices/NCCIC_ICS-CERT_Defense_in_Depth_2016_S508C.pdf
www.cisa.gov/resources-tools/resources/ics-recommended-practices
www.cisa.gov/sites/default/files/publications/Cybersecurity_Best_Practices_for_Industrial_Control_Systems.pdf
www.cisa.gov/topics/industrial-control-systems
www.cisa.gov/topics/industrial-control-systems
www.cisa.gov/uscert/ics/tips/ICS-TIP-12-146-01B
www.dhs.gov
www.dhs.gov/foia
www.dhs.gov/performance-financial-reports
www.facebook.com/CISA
www.facebook.com/sharer/sharer.php?u=https://www.cisa.gov/news-events/ics-advisories/icsa-21-250-01&title=Mitsubishi%20Electric%20MELSEC%20iQ-R%20Series%20%28Update%20B%29
www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
www.first.org/cvss/calculator/4.0#CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
www.first.org/cvss/calculator/4.0#CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
www.first.org/cvss/calculator/4.0#CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
www.instagram.com/cisagov
www.linkedin.com/company/cybersecurity-and-infrastructure-security-agency
www.linkedin.com/sharing/share-offsite/?url=https://www.cisa.gov/news-events/ics-advisories/icsa-21-250-01
www.mitsubishielectric.com/en/psirt/vulnerability/pdf/2021-008_en.pdf
www.mitsubishielectric.com/en/psirt/vulnerability/pdf/2021-009_en.pdf
www.mitsubishielectric.com/en/psirt/vulnerability/pdf/2021-010_en.pdf
www.mitsubishielectric.com/fa/download/index.html
www.mitsubishielectric.com/fa/support/index.html
www.mitsubishifa.co.th/files/dl/plc/sh081257eng/sh081257engs.pdf
www.oig.dhs.gov/
www.surveymonkey.com/r/CISA-cyber-survey?product=https://www.cisa.gov/news-events/ics-advisories/icsa-21-250-01
www.usa.gov/
www.whitehouse.gov/
www.youtube.com/@cisagov
mailto:?subject=Mitsubishi%20Electric%20MELSEC%20iQ-R%20Series%20%28Update%20B%29&body=www.cisa.gov/news-events/ics-advisories/icsa-21-250-01
6.4 Medium
CVSS2
Attack Vector
NETWORK
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
NONE
AV:N/AC:L/Au:N/C:P/I:P/A:N
9.1 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
7.4 High
AI Score
Confidence
High
0.004 Low
EPSS
Percentile
73.9%