CVSS2
Attack Vector
NETWORK
Attack Complexity
MEDIUM
Authentication
NONE
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
PARTIAL
AV:N/AC:M/Au:N/C:N/I:N/A:P
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
EPSS
Percentile
46.8%
This updated advisory is a follow-up to the original advisory titled ICSA-22-132-08 Siemens Industrial Products with OPC UA that was published May 12, 2022, on the ICS webpage on cisa.gov/ICS.
Successful exploitation of this vulnerability could crash the device by sending uncertain status code in a response message.
The following Siemens industrial products are affected:
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The OPC UA ANSIC stack (also called Legacy C-stack) was reported to crash when an unexpected OPC UA response message status code was accessed via the synchronous Client API. The vulnerability was found in generated code of the OPC Foundation C-stack. An unexpected status code in response messages will result in null pointer dereference, leading to a ping-of-death crash. This affects a client, but it might also affect a server when it uses OpcUa_ClientApi_RegisterServer (e.g., register at Local Discovery Server). A specially crafted UA server or machine-in-the-middle attacker can cause the OPC UA application to crash by sending uncertain status code in response messages.
CVE-2021-45117 has been assigned to this vulnerability. A CVSS v3 base score of 6.5 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H).
Siemens reported this vulnerability to CISA.
Siemens has recommended the following:
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Siemens has identified the following specific workarounds and mitigations to reduce risk:
As a general security measure, Siemens recommends protecting network access to devices with appropriate mechanisms. 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.
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For additional information, please refer to Siemens Security Advisory SSA-285795 in HTML or CSAF.
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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.
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-45117
cert-portal.siemens.com/productcert/csaf/ssa-285795.json
cert-portal.siemens.com/productcert/html/ssa-285795.html
cisa.gov/ics
cisa.gov/ics
cisasurvey.gov1.qualtrics.com/jfe/form/SV_9n4TtB8uttUPaM6?product=https://www.cisa.gov/news-events/ics-advisories/icsa-22-132-08
cwe.mitre.org/data/definitions/476.html
public.govdelivery.com/accounts/USDHSCISA/subscriber/new?topic_id=USDHSCISA_138
support.industry.siemens.com/cs/ww/en/view/109746530/
support.industry.siemens.com/cs/ww/en/view/109746530/
support.industry.siemens.com/cs/ww/en/view/109746530/
support.industry.siemens.com/cs/ww/en/view/109807351/
support.industry.siemens.com/cs/ww/en/view/109808270/
support.industry.siemens.com/cs/ww/en/view/109811815/
twitter.com/CISAgov
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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.dhs.gov/foia
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www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
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CVSS2
Attack Vector
NETWORK
Attack Complexity
MEDIUM
Authentication
NONE
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
PARTIAL
AV:N/AC:M/Au:N/C:N/I:N/A:P
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
EPSS
Percentile
46.8%