8.2 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
NONE
Availability Impact
LOW
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:L
7.5 High
AI Score
Confidence
High
7.2 High
CVSS2
Access Vector
LOCAL
Access Complexity
LOW
Authentication
NONE
Confidentiality Impact
COMPLETE
Integrity Impact
COMPLETE
Availability Impact
COMPLETE
AV:L/AC:L/Au:N/C:C/I:C/A:C
0.003 Low
EPSS
Percentile
68.7%
This updated advisory is a follow-up to the advisory update titled ICSA-20-196-05 Siemens UMC Stack (Update G) that was published April 13, 2021, to the ICS webpage on us-cert.cisa.gov.
Successful exploitation of these vulnerabilities could allow an attacker to cause a partial denial-of-service condition on the UMC component of the affected devices under certain circumstances. This could also allow an attacker to locally escalate privileges from a user with administrative privileges to execute code with SYSTEM level privileges.
Siemens reports that some of the vulnerabilities affect the following UMC components. For a complete list of which specific vulnerabilities affect each of these products, please see Siemens security advisory SSA-841348:
--------- Begin Update H Part 1 of 2 ---------
--------- End Update H Part 1 of 2 ---------
A component within the affected application calls a helper binary with SYSTEM privileges during startup while the call path is not quoted.
CVE-2020-7581 has been assigned to this vulnerability. A CVSS v3 base score of 6.7 has been calculated; the CVSS vector string is (AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H).
Sending multiple specially crafted packets to the affected service could cause a partial remote denial-of-service condition, which would cause the service to restart itself.
CVE-2020-7587 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:N/S:U/C:L/I:N/A:L).
Sending a specially crafted packet to the affected service could cause a partial remote denial-of-service condition, which would cause the service to restart itself.
CVE-2020-7588 has been assigned to this vulnerability. A CVSS v3 base score of 5.3 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L).
Victor Fidalgo of INCIBE and Reid Wightman of Dragos reported these vulnerabilities to Siemens.
Siemens recommends users upgrade affected products if upgrade are available for those products:
--------- Begin Update H Part 2 of 2 ---------
--------- End Update H Part 2 of 2 ---------
For products that do not have an update, Siemens has identified the following specific workarounds and mitigations customers can apply to reduce the risk:
As a general security measure, Siemens strongly 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.
Additional information on Industrial Security by Siemens can be found at: <https://www.siemens.com/industrialsecurity>
For more information on these vulnerabilities and associated software updates, please see Siemens security advisory SSA-841348
CISA recommends users take the following measures to protect themselves from social engineering attacks:
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-12-146-01BβTargeted 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 these vulnerabilities.
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2020-7581
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2020-7587
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2020-7588
cwe.mitre.org/data/definitions/20.html
cwe.mitre.org/data/definitions/400.html
cwe.mitre.org/data/definitions/428.html
public.govdelivery.com/accounts/USDHSCISA/subscriber/new?topic_id=USDHSCISA_138
support.industry.siemens.com/cs/ww/en/view/109768994
support.industry.siemens.com/cs/ww/en/view/109768994
support.industry.siemens.com/cs/ww/en/view/109775861
support.industry.siemens.com/cs/ww/en/view/109775861
support.industry.siemens.com/cs/ww/en/view/109781888
support.industry.siemens.com/cs/ww/en/view/109781888
support.sw.siemens.com/
support.sw.siemens.com/
support.sw.siemens.com/
support.sw.siemens.com/
support.sw.siemens.com/
support.sw.siemens.com/
twitter.com/CISAgov
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us-cert.cisa.gov/ics
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
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mailto:?subject=Siemens%20UMC%20Stack%20%28Update%20H%29&body=www.cisa.gov/news-events/ics-advisories/icsa-20-196-05
8.2 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
NONE
Availability Impact
LOW
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:L
7.5 High
AI Score
Confidence
High
7.2 High
CVSS2
Access Vector
LOCAL
Access Complexity
LOW
Authentication
NONE
Confidentiality Impact
COMPLETE
Integrity Impact
COMPLETE
Availability Impact
COMPLETE
AV:L/AC:L/Au:N/C:C/I:C/A:C
0.003 Low
EPSS
Percentile
68.7%