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AUSCERT External Security Bulletin Redistribution
ESB-2021.2399
Advisories (icsa-21-194-05 and icsa-21-194-06) Siemens
SIMATIC Software Products
15 July 2021
===========================================================================
AusCERT Security Bulletin Summary
---------------------------------
Product: Siemens SIMATIC Software Products
Publisher: ICS-CERT
Operating System: Network Appliance
Impact/Access: Execute Arbitrary Code/Commands -- Existing Account
Overwrite Arbitrary Files -- Existing Account
Denial of Service -- Existing Account
Resolution: Patch/Upgrade
CVE Names: CVE-2021-31894 CVE-2021-31893
Original Bulletin:
https://us-cert.cisa.gov/ics/advisories/icsa-21-194-05
https://us-cert.cisa.gov/ics/advisories/icsa-21-194-06
Comment: This bulletin contains two (2) ICS-CERT security advisories.
- --------------------------BEGIN INCLUDED TEXT--------------------
ICS Advisory (ICSA-21-194-05)
Siemens SIMATIC Software Products
Original release date: July 13, 2021
Legal Notice
All information products included in https://us-cert.cisa.gov/ics are provided
"as is" for informational purposes only. The Department of Homeland Security
(DHS) does not provide any warranties of any kind regarding any information
contained within. DHS does not endorse any commercial product or service,
referenced in this product or otherwise. Further dissemination of this product
is governed by the Traffic Light Protocol (TLP) marking in the header. For more
information about TLP, see https://us-cert.cisa.gov/tlp/ .
1. EXECUTIVE SUMMARY
o CVSS v3 7.8
o ATTENTION : Low attack complexity
o Vendor : Siemens
o Equipment : SIMATIC Software Products
o Vulnerability : Classic Buffer Overflow
2. RISK EVALUATION
Successful exploitation of this vulnerability could allow an attacker to
manipulate project files, create a denial-of-service condition or remotely
execute code.
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
Siemens reports this vulnerability affects the following SIMATIC software
products:
o SIMATIC PCS 7 v8.2 and earlier: All versions
o SIMATIC PCS 7 v9.0: All versions prior to 9.0 SP3
o SIMATIC PDM: All versions prior to v9.2
o SIMATIC STEP 7 v5.X: All versions prior to v5.6 SP2 HF3
o SINAMICS STARTER (containing STEP 7 OEM version): All versions prior to
v5.4 HF2
3.2 VULNERABILITY OVERVIEW
3.2.1 BUFFER COPY WITHOUT CHECKING SIZE OF INPUT ('CLASSIC BUFFER OVERFLOW')
CWE-120
The affected software contains a buffer overflow vulnerability while handling
certain files that may allow a local attacker to trigger a denial-of-service
condition or potentially lead to remote code execution.
CVE-2021-31893 has been assigned to this vulnerability. A CVSS v3 base score of
7.8 has been calculated; the CVSS vector string is ( AV:L/AC:L/PR:L/UI:N/S:U/
C:H/I:H/A:H ).
3.3 BACKGROUND
o CRITICAL INFRASTRUCTURE SECTORS : Chemical, Critical Manufacturing, Energy,
Food and Agriculture, Water and Wastewater Systems
o COUNTRIES/AREAS DEPLOYED : Worldwide
o COMPANY HEADQUARTERS LOCATION : Germany
3.4 RESEARCHER
Uri Katz from Claroty reported this vulnerability to Siemens.
4. MITIGATIONS
Siemens has released updates for the following products:
o SIMATIC PCS 7 v9.0: Update to v9.0 SP3 or later (To obtain SIMATIC PCS 7
v9.0 SP3 contact your local customer support)
o SIMATIC PDM: Update to v9.2 or later
o SIMATIC STEP 7 V5.X: Update to v5.6 SP2 HF3 or later
o SINAMICS STARTER (containing STEP 7 OEM version): Update to v5.4 HF2 or
later
Siemens has identified the following specific workarounds and mitigations
customers can apply to reduce the risk:
o Restrict access to project files on the engineering station to trusted
users
o Only use project files from trusted sources
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 Siemens 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
Please see Siemens Security Advisory ssa-641963 for more information.
CISA recommends users take defensive measures to minimize the risk of
exploitation of this vulnerability. Specifically, users should:
o Minimize network exposure for all control system devices and/or systems,
and ensure that they are not accessible from the Internet .
o Locate control system networks and remote devices behind firewalls, and
isolate them from the business network.
o When remote access is required, use secure methods, such as Virtual Private
Networks (VPNs), recognizing that VPNs may have vulnerabilities and should
be updated to the most current version available. Also recognize that VPN
is only as secure as the connected devices.
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-12-146-01B--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.
For any questions related to this report, please contact the CISA at:
Email: CISAservicedesk@cisa.dhs.gov
Toll Free: 1-888-282-0870
CISA continuously strives to improve its products and services. You can help by
choosing one of the links below to provide feedback about this product.
- -------------------------------------------------------------------------------
ICS Advisory (ICSA-21-194-06)
Siemens SIMATIC Software Products
Original release date: July 13, 2021
Legal Notice
All information products included in https://us-cert.cisa.gov/ics are provided
"as is" for informational purposes only. The Department of Homeland Security
(DHS) does not provide any warranties of any kind regarding any information
contained within. DHS does not endorse any commercial product or service,
referenced in this product or otherwise. Further dissemination of this product
is governed by the Traffic Light Protocol (TLP) marking in the header. For more
information about TLP, see https://us-cert.cisa.gov/tlp/ .
1. EXECUTIVE SUMMARY
o CVSS v3 7.3
o ATTENTION : Low attack complexity
o Vendor : Siemens
o Equipment : SIMATIC Software Products
o Vulnerability : Incorrect Permission Assignment for Critical Resource
2. RISK EVALUATION
Successful exploitation of this vulnerability could allow an attacker to
manipulate parameters or the behavior of devices configured by the affected
software products.
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
Siemens reports this vulnerability affects the following SIMATIC software
products:
o SIMATIC PCS 7 V8.2 and earlier: All versions
o SIMATIC PCS 7 V9.X: All versions
o SIMATIC PDM: All versions
o SIMATIC STEP 7 V5.X: All versions prior to v5.7
o SINAMICS STARTER (containing STEP 7 OEM version): All versions
3.2 VULNERABILITY OVERVIEW
3.2.1 INCORRECT PERMISSION ASSIGNMENT FOR CRITICAL RESOURCE CWE-732
An attacker could change the content of certain metafiles and subsequently
manipulate parameters or the behavior of devices that would be later configured
by the affected software.
CVE-2021-31894 has been assigned to this vulnerability. A CVSS v3 base score of
7.3 has been calculated; the CVSS vector string is ( AV:L/AC:L/PR:L/UI:N/S:C/
C:N/I:H/A:L ).
3.3 BACKGROUND
o CRITICAL INFRASTRUCTURE SECTORS : Chemical, Critical Manufacturing, Energy,
Food and Agriculture, Water and Wastewater Systems
o COUNTRIES/AREAS DEPLOYED : Worldwide
o COMPANY HEADQUARTERS LOCATION : Germany
3.4 RESEARCHER
Siemens reported this vulnerability to CISA.
4. MITIGATIONS
Siemens has released updates for the following product:
o SIMATIC STEP 7 V5.X: Update to V5.7 or later
Siemens has identified the following specific workarounds and mitigations users
can apply to reduce the risk:
o Restrict access to engineering stations to trusted users only
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 Siemens 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
Please see Siemens Security Advisory ssa-661034 for more information.
CISA recommends users take defensive measures to minimize the risk of
exploitation of this vulnerability. Specifically, users should:
o Minimize network exposure for all control system devices and/or systems,
and ensure that they are not accessible from the Internet .
o Locate control system networks and remote devices behind firewalls, and
isolate them from the business network.
o When remote access is required, use secure methods, such as Virtual Private
Networks (VPNs), recognizing that VPNs may have vulnerabilities and should
be updated to the most current version available. Also recognize that VPN
is only as secure as the connected devices.
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-12-146-01B--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.
For any questions related to this report, please contact the CISA at:
Email: CISAservicedesk@cisa.dhs.gov
Toll Free: 1-888-282-0870
CISA continuously strives to improve its products and services. You can help by
choosing one of the links below to provide feedback about this product.
- --------------------------END INCLUDED TEXT--------------------
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