7.5 High
CVSS2
Attack Vector
NETWORK
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:N/AC:L/Au:N/C:P/I:P/A:P
9.8 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.4 High
AI Score
Confidence
High
0.107 Low
EPSS
Percentile
95.1%
This updated advisory is a follow-up to the advisory update titled ICSA-21-131-04 Siemens Medium Voltage Products (Update A) that was published May 11, 2021, to the ICS webpage on us-cert.cisa.gov.
Successful exploitation of this vulnerability could allow an attacker to gain full remote access to the HMI.
Siemens reports this vulnerability affects the following SINAMICS products with remote access enabled on SIMATIC comfort HMI Panels:
SmartVNC has a heap allocation leak vulnerability in the server Tight encoder, which could result in a denial-of-service condition.
CVE-2021-27383 has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).
SmartVNC has an out-of-bounds memory access vulnerability in the device layout handler, represented by a binary data stream on client side, which could result in code execution.
CVE-2021-27384 has been assigned to this vulnerability. A CVSS v3 base score of 9.8 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).
A remote attacker could send specially crafted packets to SmartVNC device layout handler on client side, which could influence the amount of resources consumed and result in a denial-of-service (infinite loop) condition.
CVE-2021-27385 has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).
SmartVNC has a heap allocation leak vulnerability in the device layout handler on client side, which could result in a denial-of-service condition.
CVE-2021-27386 has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).
UltraVNC Revision 1198 contains multiple memory leaks in VNC client code, which could allow an attacker to read stack memory and can be abused for information disclosure. Combined with another vulnerability, it can be used to leak stack memory and bypass ASLR.
CVE-2019-8259 has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N).
UltraVNC Revision 1199 has an out-of-bounds read vulnerability in VNC client RRE decoder code, caused by multiplication overflow.
CVE-2019-8260 has been assigned to this vulnerability. A CVSS v3 base score of 9.8 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).
UltraVNC Revision 1199 has an out-of-bounds read vulnerability in VNC code inside client CoRRE decoder, caused by multiplication overflow.
CVE-2019-8261 has been assigned to this vulnerability. A CVSS v3 base score of 9.8 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).
UltraVNC Revision 1203 has multiple heap buffer overflow vulnerabilities in VNC client code inside Ultra decoder, which could result in code execution.
CVE-2019-8262 has been assigned to this vulnerability. A CVSS v3 base score of 9.8 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).
UltraVNC Revision 1205 has a stack-based buffer overflow vulnerability in VNC client code inside ShowConnInfo routine, which could lead to a denial-of-service condition.
CVE-2019-8263 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).
UltraVNC Revision 1203 has an out-of-bounds access vulnerability in VNC client inside Ultra2 decoder, which could result in code execution.
CVE-2019-8264 has been assigned to this vulnerability. A CVSS v3 base score of 9.8 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).
UltraVNC Revision 1207 has multiple out-of-bounds access vulnerabilities connected with improper usage of SETPIXELS macro in VNC client code, which could result in code execution.
CVE-2019-8265 has been assigned to this vulnerability. A CVSS v3 base score of 9.8 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).
UltraVNC Revision 1211 has multiple improper null termination vulnerabilities in VNC server code, which could result in out-of-bounds data being accessed by remote users.
CVE-2019-8275 has been assigned to this vulnerability. A CVSS v3 base score of 9.8 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).
UltraVNC Revision 1211 contains multiple memory leaks in VNC server code, which could allow an attacker to read stack memory and can be abused for information disclosure.
CVE-2019-8277 has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N).
UltraVNC Revision 1203 has out-of-bounds access vulnerability in VNC client inside RAW decoder, which could result in code execution.
CVE-2019-8280 has been assigned to this vulnerability. A CVSS v3 base score of 9.8 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).
Siemens reported this vulnerability to CISA.
--------- Begin Update B Part 1 of 2 ---------
Only HMI image versions prior to v16 Update 3a are affected. Siemens recommends updating the HMI Panel, as included in the following products:
--------- End Update B Part 1 of 2 ---------
Siemens has identified the following specific workarounds and mitigations users can apply to reduce the risk:
--------- Begin Update B Part 2 of 2 ---------
--------- End Update B Part 2 of 2 ---------
As a general security measure, Siemens strongly recommends users protect network access to devices with appropriate mechanisms. In order to operate the devices in a protected IT environment, Siemens recommends users configure the environment according to Siemensβ operational guidelines for industrial security, and follow the recommendations in the product manuals. Additional information on industrial security by Siemens can be found at: <https://www.siemens.com/industrialsecurity>
For additional information see Siemens Security Advisory SSA-286838
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-12-146-01BβTargeted 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. These vulnerabilities have a high attack complexity.
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2019-8259
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2019-8260
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2019-8261
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2019-8262
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2019-8263
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2019-8264
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2019-8265
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2019-8275
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2019-8277
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2019-8280
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-27383
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-27384
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-27385
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-27386
cert-portal.siemens.com/operational-guidelines-industrial-security.pdf
cert-portal.siemens.com/productcert/pdf/ssa-286838.pdf
cwe.mitre.org/data/definitions/119.html
cwe.mitre.org/data/definitions/119.html
cwe.mitre.org/data/definitions/121.html
cwe.mitre.org/data/definitions/122.html
cwe.mitre.org/data/definitions/125.html
cwe.mitre.org/data/definitions/125.html
cwe.mitre.org/data/definitions/170.html
cwe.mitre.org/data/definitions/400.html
cwe.mitre.org/data/definitions/665.html
cwe.mitre.org/data/definitions/665.html
cwe.mitre.org/data/definitions/788.html
cwe.mitre.org/data/definitions/788.html
cwe.mitre.org/data/definitions/788.html
cwe.mitre.org/data/definitions/788.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/
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support.industry.siemens.com/cs/ww/en/view/109751848/
support.industry.siemens.com/cs/ww/en/view/109763890/
support.industry.siemens.com/cs/ww/en/view/109763890/
support.industry.siemens.com/cs/ww/en/view/109763890/
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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/sites/default/files/recommended_practices/NCCIC_ICS-CERT_Defense_in_Depth_2016_S508C.pdf
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www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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7.5 High
CVSS2
Attack Vector
NETWORK
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:N/AC:L/Au:N/C:P/I:P/A:P
9.8 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.4 High
AI Score
Confidence
High
0.107 Low
EPSS
Percentile
95.1%