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
NONE
Availability Impact
HIGH
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
AI Score
Confidence
High
EPSS
Percentile
42.5%
CVSS v3 7.5
ATTENTION: Exploitable remotely/low skill level to exploit
Vendor: Siemens
Equipment: SIMATIC S7-300 CPU
Vulnerability: Improper Input Validation
Successful exploitation of this vulnerability could crash the device being accessed, resulting in a denial-of-service condition.
Siemens reports the following SIMATIC S7-300 CPU product is affected:
3.2.1 IMPROPER INPUT VALIDATION CWE-20
The affected CPUs improperly validate S7 communication packets, which could cause a denial-of-service condition of the CPU. The CPU will remain in DEFECT mode until manual restart.
Successful exploitation requires an attacker to send a specially crafted S7 communication packet to a communication interface of the CPU. This includes Ethernet, PROFIBUS, and Multi Point Interfaces (MPI). The vulnerability could allow a denial-of-service condition of the core functionality of the CPU.
CVE-2018-16561 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).
China Industrial Control Systems Cyber Emergency Response Team (CIC) reported this vulnerability to Siemens.
Siemens recommends users update to Version 3.X.16, which can be downloaded from the following link:
<https://support.industry.siemens.com/cs/ww/en/ps/13752/dl>
Siemens has identified the following specific workarounds and mitigations users can apply to reduce the risk:
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 (<https://www.siemens.com/cert/operational-guidelines-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 this vulnerability and associated software updates, please see Siemens security advisory SSA-306710 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 this vulnerability.
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2018-16561
cisasurvey.gov1.qualtrics.com/jfe/form/SV_9n4TtB8uttUPaM6?product=https://www.cisa.gov/news-events/ics-advisories/icsa-19-043-04
cwe.mitre.org/data/definitions/20.html
public.govdelivery.com/accounts/USDHSCISA/subscriber/new?topic_id=USDHSCISA_138
support.industry.siemens.com/cs/ww/en/ps/13752/dl
twitter.com/CISAgov
twitter.com/intent/tweet?text=Siemens%20SIMATIC%20S7-300%20CPU+https://www.cisa.gov/news-events/ics-advisories/icsa-19-043-04
www.dhs.gov
www.dhs.gov/foia
www.dhs.gov/performance-financial-reports
www.facebook.com/CISA
www.facebook.com/sharer/sharer.php?u=https://www.cisa.gov/news-events/ics-advisories/icsa-19-043-04&title=Siemens%20SIMATIC%20S7-300%20CPU
www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
www.instagram.com/cisagov
www.linkedin.com/company/cybersecurity-and-infrastructure-security-agency
www.linkedin.com/sharing/share-offsite/?url=https://www.cisa.gov/news-events/ics-advisories/icsa-19-043-04
www.oig.dhs.gov/
www.siemens.com/cert/advisories
www.siemens.com/cert/operational-guidelines-industrial-security
www.siemens.com/industrialsecurity
www.usa.gov/
www.whitehouse.gov/
www.youtube.com/@cisagov
mailto:?subject=Siemens%20SIMATIC%20S7-300%20CPU&body=www.cisa.gov/news-events/ics-advisories/icsa-19-043-04
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
NONE
Availability Impact
HIGH
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
AI Score
Confidence
High
EPSS
Percentile
42.5%