CVSS2
Attack Vector
NETWORK
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
COMPLETE
AV:N/AC:L/Au:N/C:N/I:N/A:C
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
LOW
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
AI Score
Confidence
High
EPSS
Percentile
42.5%
As of January 10, 2023, CISA will no longer be updating ICS security advisories for Siemens product vulnerabilities beyond the initial advisory. For the most up-to-date information on vulnerabilities in this advisory, please see Siemensβ ProductCERT Security Advisories (CERT Services | Services | Siemens Global).
CVSS v3 8.2
ATTENTION: Exploitable remotely/low skill level to exploit
Vendor: Siemens
Equipment: S7-400 CPUs
Vulnerabilities: Improper Input Validation
This updated advisory is a follow-up to the original advisory titled ICSA-18-317-02 Siemens S7-400 CPUs (Update A) that was published November 13, 2018, on the NCCIC/ICS-CERT website.
Successful exploitation of these vulnerabilities could crash the device being accessed which may require a manual reboot or firmware re-image to bring the system back to normal operation.
Siemens reports that the vulnerabilities affect the following SIMATIC S7-400 products:
--------- Begin Update B Part 1 of 1 ---------
--------- End Update B Part 1 of 1 ---------
Specially crafted packets sent to Port 102/TCP via Ethernet interface, via PROFIBUS, or via multi-point interfaces (MPI) could cause the affected devices to go into defect mode. Manual reboot is required to resume normal operation.
CVE-2018-16556 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).
Specially crafted packets sent to Port 102/TCP via Ethernet interface via PROFIBUS or MPI could cause a denial-of-service condition on affected devices. Recovery may require flashing with a firmware image.
If access protection is not configured, no privileges are required to exploit this vulnerability.
CVE-2018-16557 has been assigned to this vulnerability. A CVSS v3 base score of 8.2 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H).
Zhang JiaWei and Qing YuLong from CNCERT/CC reported these vulnerabilities to Siemens.
Siemens recommends implementing the following mitigations:
<https://support.industry.siemens.com/cs/ww/en/view/109476571>
<https://support.industry.siemens.com/cs/ww/en/view/109474550>
<https://www.siemens.com/cert/operational-guidelines-industrial-security>
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 Siemensβ operational guidelines for industrial security (download: <https://www.siemens.com/cert/operational-guidelines-industrial-security>), and following the recommendations in the product manuals.
For more information on these vulnerabilities and associated software updates, please see Siemens security advisory SSA-113131 on their website:
<https://www.siemens.com/cert/advisories>
NCCIC recommends users take defensive measures to minimize the risk of exploitation of this vulnerability. Specifically, users should:
NCCIC reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures.
NCCIC also provides a section for control systems security recommended practices on the ICS-CERT web page. 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-CERT website 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 NCCIC for tracking and correlation against other incidents.
No known public exploits specifically target these vulnerabilities.
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2018-16556
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CVSS2
Attack Vector
NETWORK
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
COMPLETE
AV:N/AC:L/Au:N/C:N/I:N/A:C
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
LOW
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
AI Score
Confidence
High
EPSS
Percentile
42.5%