CVSS2
Attack Vector
NETWORK
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:N/AC:L/Au:N/C:P/I:P/A:P
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
AI Score
Confidence
High
EPSS
Percentile
77.0%
Successful exploitation of these vulnerabilities could allow an attacker to upload, alter, and/or download the PLC user program. An attacker could also access the PLC web server and hijack the controllers, resulting in the manipulation and/or suspension of the PLC output.
The following IDEC PLCs are affected:
An attacker may obtain the user credentials from the communication between the PLC and the software. As a result, the PLC user program may be uploaded, altered, and/or downloaded.
CVE-2021-37400 has been assigned to this vulnerability. A CVSS v3 base score of 7.6 has been calculated; the CVSS vector string is (AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L).
An attacker may obtain the user credentials from file servers, backup repositories, or ZLD files saved in SD cards. As a result, the PLC user program may be uploaded, altered, and/or downloaded.
CVE-2021-37401 has been assigned to this vulnerability. A CVSS v3 base score of 7.6 has been calculated; the CVSS vector string is (AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L).
An attacker may obtain the PLC web server user credentials from the communication between the PLC and the software. As a result, the complete access privileges to the PLC web server may be obtained, and manipulation of the PLC output and/or suspension of the PLC may be conducted.
CVE-2021-20826 has been assigned to this vulnerability. A CVSS v3 base score of 7.6 has been calculated; the CVSS vector string is (AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L).
An attacker may obtain the PLC web server user credentials from file servers, backup repositories, or ZLD files saved in SD cards. As a result, the attacker may access the PLC web server and hijack the PLC, and manipulation of the PLC output and/or suspension of the PLC may be conducted.
CVE-2021-20827 has been assigned to this vulnerability. A CVSS v3 base score of 7.6 has been calculated; the CVSS vector string is (AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L).
Khalid Ansari of FM Approvals reported these vulnerabilities to IDEC Corporation.
Apply the appropriate software update according to the information provided by the developer.
Applying the below workarounds can mitigate the impacts of these vulnerabilities.
For more information, refer to the information provided by the developer (document in Japanese).
CISA recommends users take defensive measures to minimize the risk of exploitation of this vulnerability. Specifically, users should:
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. 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 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 these vulnerabilities.
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-20826
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-20827
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-37400
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-37401
cisasurvey.gov1.qualtrics.com/jfe/form/SV_9n4TtB8uttUPaM6?product=https://www.cisa.gov/news-events/ics-advisories/icsa-22-006-03
cwe.mitre.org/data/definitions/256.html
cwe.mitre.org/data/definitions/256.html
cwe.mitre.org/data/definitions/523.html
cwe.mitre.org/data/definitions/523.html
public.govdelivery.com/accounts/USDHSCISA/subscriber/new?topic_id=USDHSCISA_138
twitter.com/CISAgov
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www.cisa.gov/uscert/ics
www.cisa.gov/uscert/ics
www.cisa.gov/uscert/ics/alerts/ICS-ALERT-10-301-01
www.cisa.gov/uscert/ics/recommended-practices
www.cisa.gov/uscert/ics/tips/ICS-TIP-12-146-01B
www.cisa.gov/uscert/sites/default/files/recommended_practices/NCCIC_ICS-CERT_Defense_in_Depth_2016_S508C.pdf
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www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L
www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L
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www.idec.com/home/lp/pdf/2021-12-24-PLC.pdf
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CVSS2
Attack Vector
NETWORK
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:N/AC:L/Au:N/C:P/I:P/A:P
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
AI Score
Confidence
High
EPSS
Percentile
77.0%