This updated advisory is a follow-up to the original advisory titled ICSA-21-222-07 Siemens SIMATIC NET CP that was published August 10, 2021, on the ICS webpage on cisa.gov/ics.
Successful exploitation of these vulnerabilities could allow a remote attacker to access sensitive information and execute arbitrary code.
The following Siemens products are affected:
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The affected products are vulnerable to an out-of-bounds read vulnerability in mod_cap via the cap_text.ccap_to_text function, which could lead to information disclosure.
CVE-2020-9272 has been assigned to this vulnerability. A CVSS v3.1 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).
A malicious attacker could corrupt the memory pool by interrupting the data transfer channel. This triggers a use-after-free condition in alloc_pool in pool.c, which could lead to remote code execution.
CVE-2020-9273 has been assigned to this vulnerability. A CVSS v3.1 base score of 8.8 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H).
Siemens reported these vulnerabilities to CISA.
Siemens recommends users update to the latest software version:
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Siemens has identified the following specific workarounds and mitigations users can apply to reduce the risk:
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 Siemens operational guidelines for industrial security, and follow the recommendations in the product manual.
Additional information on industrial security by Siemens can be found on the Siemens industrial security webpage.
For more information about this issue, please see Siemens Security Advisory SSA-679335
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/ics 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/ics 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 these vulnerabilities.
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2020-9272
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2020-9273
cert-portal.siemens.com/operational-guidelines-industrial-security.pdf
cert-portal.siemens.com/productcert/pdf/ssa-679335.pdf
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