CVSS2
Attack Vector
ADJACENT_NETWORK
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
NONE
AV:A/AC:L/Au:N/C:P/I:P/A:N
CVSS3
Attack Vector
ADJACENT
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
LOW
Integrity Impact
LOW
Availability Impact
NONE
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
AI Score
Confidence
High
EPSS
Percentile
25.0%
This updated advisory is a follow-up to the original advisory titled ICSA-21-257-13 Siemens LOGO! CMR and SIMATIC RTU 3000 that was published September 14, 2021, on the ICS webpage on www.cisa.gov/uscert.
Successful exploitation of this vulnerability could allow an attacker with network access to the LAN interface of an affected device to hijack an ongoing connection or spoof a new one.
The following versions of LOGO! controllers and SIMATIC monitors are affected:
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The underlying TCP/IP stack does not properly calculate the random numbers used as ISN (Initial Sequence Numbers). An adjacent attacker with network access to the LAN interface could interfere with traffic, spoof the connection, and gain access to sensitive information.
CVE-2021-37186 has been assigned to this vulnerability. A CVSS v3 base score of 5.4 has been calculated; the CVSS vector string is (AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N).
Siemens reported this vulnerability to CISA.
Siemens has identified the following specific workarounds and mitigations users can apply to reduce the risk:
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As a general security measure, Siemens strongly recommends protecting network access to devices with appropriate mechanisms. In order to operate the devices in a protected IT environment, Siemens recommends configuring the environment according to Siemensβ operational guidelines for industrial security and following the recommendations in the product manuals.
Additional information on industrial security by Siemens can be found at: <https://www.siemens.com/industrialsecurity>
For more information about this issue, please see Siemens Security Advisory SSA-316383
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-12-146-01BβTargeted 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 is not exploitable remotely.
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-37186
cert-portal.siemens.com/productcert/pdf/ssa-316383.pdf
cisasurvey.gov1.qualtrics.com/jfe/form/SV_9n4TtB8uttUPaM6?product=https://www.cisa.gov/news-events/ics-advisories/icsa-21-257-13
cwe.mitre.org/data/definitions/330.html
public.govdelivery.com/accounts/USDHSCISA/subscriber/new?topic_id=USDHSCISA_138
support.industry.siemens.com/cs/ww/en/view/109800267/
support.industry.siemens.com/cs/ww/en/view/109802779/
twitter.com/CISAgov
twitter.com/intent/tweet?text=Siemens%20LOGO%21%20CMR%20and%20SIMATIC%20RTU%203000%20%28Update%20A%29+https://www.cisa.gov/news-events/ics-advisories/icsa-21-257-13
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
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:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
www.instagram.com/cisagov
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www.oig.dhs.gov/
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www.usa.gov/
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CVSS2
Attack Vector
ADJACENT_NETWORK
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
NONE
AV:A/AC:L/Au:N/C:P/I:P/A:N
CVSS3
Attack Vector
ADJACENT
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
LOW
Integrity Impact
LOW
Availability Impact
NONE
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
AI Score
Confidence
High
EPSS
Percentile
25.0%