7.1 High
CVSS2
Attack Vector
NETWORK
Attack Complexity
MEDIUM
Authentication
NONE
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
COMPLETE
AV:N/AC:M/Au:N/C:N/I:N/A:C
5.9 Medium
CVSS3
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
5.9 Medium
AI Score
Confidence
High
0.006 Low
EPSS
Percentile
77.7%
This updated advisory is a follow-up to the original advisory titled ICSA-21-280-04 Mitsubishi Electric MELSEC iQ-R Series C Controller Module that was published October 7, 2021, to the ICS webpage on us-cert.cisa.gov.
Successful exploitation of this vulnerability could prevent the module from starting up. If successfully exploited, a system reset would be required for recovery.
The following modules of the MELSEC iQ-R Series C Controller Module are affected:
--------- Begin Update B Part 1 of 2 ---------
--------- End Update B Part 1 of 2 ---------
The potential for a denial-of-service condition exists in MELSEC iQ-R series C Controller Module due to uncontrolled resource consumption caused by an attacker sending a large number of packets to the module at start up in a short time.
CVE-2021-20600 has been assigned to this vulnerability. A CVSS v3 base score of 6.8 has been calculated; the CVSS vector string is (AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H).
Mitsubishi Electric Corporation reported this vulnerability to CISA.
--------- Begin Update B Part 2 of 2 ---------
Mitsubishi Electric recommends users update affected devices to Firmware Version 17 or later. For specific update instructions and additional details see the Mitsubishi Electric advisory.
--------- End Update B Part 2 of 2 ---------
If a System WDT error occurs at start up, there is a possibility the C Controller Module has been attacked. In this case, disconnect the LAN cable of the module and restart. After confirming the module has started normally, make a LAN connection.
Regardless of whether the above error occurred, Mitsubishi Electric recommends users take the following mitigation measures to minimize the risk of exploiting this vulnerability:
For specific update instructions and additional details see the Mitsubishi Electric advisory.
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 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:
No known public exploits specifically target this vulnerability. This vulnerability has a high attack complexity.
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-20600
cwe.mitre.org/data/definitions/400.html
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%20C%20Controller%20Module%20%28Update%20B%29+https://www.cisa.gov/news-events/ics-advisories/icsa-21-280-04
us-cert.cisa.gov/ics
us-cert.cisa.gov/ics
us-cert.cisa.gov/ics/alerts/ICS-ALERT-10-301-01
us-cert.cisa.gov/ics/recommended-practices
us-cert.cisa.gov/ics/tips/ICS-TIP-12-146-01B
us-cert.cisa.gov/ncas/tips/ST04-014
us-cert.cisa.gov/sites/default/files/publications/emailscams_0905.pdf
us-cert.cisa.gov/sites/default/files/recommended_practices/NCCIC_ICS-CERT_Defense_in_Depth_2016_S508C.pdf
www.dhs.gov
www.dhs.gov/foia
www.dhs.gov/performance-financial-reports
www.facebook.com/CISA
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www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H
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-21-280-04
www.mitsubishielectric.com/en/psirt/vulnerability/pdf/2021-015_en.pdf
www.mitsubishielectric.com/en/psirt/vulnerability/pdf/2021-015_en.pdf
www.oig.dhs.gov/
www.surveymonkey.com/r/CISA-cyber-survey?product=https://www.cisa.gov/news-events/ics-advisories/icsa-21-280-04
www.usa.gov/
www.whitehouse.gov/
www.youtube.com/@cisagov
mailto:?subject=Mitsubishi%20Electric%20MELSEC%20iQ-R%20Series%20C%20Controller%20Module%20%28Update%20B%29&body=www.cisa.gov/news-events/ics-advisories/icsa-21-280-04
7.1 High
CVSS2
Attack Vector
NETWORK
Attack Complexity
MEDIUM
Authentication
NONE
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
COMPLETE
AV:N/AC:M/Au:N/C:N/I:N/A:C
5.9 Medium
CVSS3
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
5.9 Medium
AI Score
Confidence
High
0.006 Low
EPSS
Percentile
77.7%