CVSS2
Attack Vector
LOCAL
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
NONE
Availability Impact
NONE
AV:L/AC:L/Au:N/C:P/I:N/A:N
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
NONE
Availability Impact
NONE
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
AI Score
Confidence
High
EPSS
Percentile
23.8%
This updated advisory is a follow-up to the original advisory titled ICSA-21-350-13 Siemens Questa and ModelSim that was published December 16, 2021, on the ICS webpage on cisa.gov/ics.
Successful exploitation of this vulnerability could allow access to unencrypted data.
The following versions of Questa and ModelSim, integrated circuit simulators, are affected:
The affected product is vulnerable to insufficiently protected keys required for decrypting intellectual property data, which could allow an attacker to discover the keys and bypass the protection intended by IEEE 1735 standard.
CVE-2021-42023 has been assigned to this vulnerability. A CVSS v3 base score of 9.0 has been assigned; the CVSS vector string is (AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N).
Julian Speith and Christof Paar from Max Planck Institute for Security and Privacy coordinated this vulnerability with Siemens.
Florian Schweins and Alexander May from Ruhr University coordinated this vulnerability with Siemens.
Siemens recommends upgrading to the lastest version of the following products, login is required:
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Siemens has identified the following specific workarounds and mitigations users can apply to reduce the risk:
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For more information, see Siemens Security Advisory SSA-400332 in HTML or CSAF.
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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 this vulnerability. This vulnerability is not exploitable remotely.
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-42023
cert-portal.siemens.com/productcert/csaf/ssa-400332.json
cert-portal.siemens.com/productcert/html/ssa-400332.html
cisasurvey.gov1.qualtrics.com/jfe/form/SV_9n4TtB8uttUPaM6?product=https://www.cisa.gov/news-events/ics-advisories/icsa-21-350-13
cwe.mitre.org/data/definitions/522.html
public.govdelivery.com/accounts/USDHSCISA/subscriber/new?topic_id=USDHSCISA_138
support.sw.siemens.com/en-US/product/852852093/
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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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mailto:?subject=Siemens%20Questa%20and%20ModelSim%20%28Update%20A%29&body=www.cisa.gov/news-events/ics-advisories/icsa-21-350-13
CVSS2
Attack Vector
LOCAL
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
NONE
Availability Impact
NONE
AV:L/AC:L/Au:N/C:P/I:N/A:N
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
NONE
Availability Impact
NONE
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
AI Score
Confidence
High
EPSS
Percentile
23.8%