7.5 High
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
8.8 High
AI Score
Confidence
High
5 Medium
CVSS2
Access Vector
NETWORK
Access Complexity
LOW
Authentication
NONE
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
PARTIAL
AV:N/AC:L/Au:N/C:N/I:N/A:P
0.004 Low
EPSS
Percentile
73.5%
This updated advisory is a follow-up to the advisory update titled ICSA-21-068-10 Siemens SCALANCE and SIMATIC libcurl (Update A) that was published March 9, 2021, to the ICS webpage on us-cert.cisa.gov.
Successful exploitation of this third-party vulnerability could allow an attacker to cause a denial-of-service condition on the affected devices.
The following Siemens products are affected by the third-party component libcurl:
--------- Begin Update B Part 1 of 2 ---------
--------- End Update B Part 1 of 2 ---------
The libcurl library Versions 7.34.0 through 7.63.0 are vulnerable to a heap out-of-bounds read condition in the code handling the end-of-response for SMTP. This vulnerability could allow an attacker to trigger a denial-of-service condition on the affected devices.
CVE-2019-3823 has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been assigned; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).
Siemens reported this vulnerability to CISA.
Siemens has identified the following specific workarounds and mitigations users can apply to reduce risk:
--------- Begin Update B Part 2 of 2 ---------
--------- End Update B Part 2 of 2 ---------
The impact of additional libcurl vulnerabilities is described in Siemens Security Advisory SSA-436177
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-12-146-01B–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.
web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2019-3823
cert-portal.siemens.com/productcert/pdf/ssa-436177.pdf
cwe.mitre.org/data/definitions/125.html
public.govdelivery.com/accounts/USDHSCISA/subscriber/new?topic_id=USDHSCISA_138
support.industry.siemens.com/cs/ww/en/view/109769665/
support.industry.siemens.com/cs/ww/en/view/109801629/
twitter.com/CISAgov
twitter.com/intent/tweet?text=%20Siemens%20SCALANCE%20and%20SIMATIC%20libcurl%20%28Update%20B%29+https://www.cisa.gov/news-events/ics-advisories/icsa-21-068-10
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
www.dhs.gov
www.dhs.gov/foia
www.dhs.gov/performance-financial-reports
www.facebook.com/CISA
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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: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-21-068-10
www.oig.dhs.gov/
www.surveymonkey.com/r/CISA-cyber-survey?product=https://www.cisa.gov/news-events/ics-advisories/icsa-21-068-10
www.usa.gov/
www.whitehouse.gov/
www.youtube.com/@cisagov
mailto:?subject=%20Siemens%20SCALANCE%20and%20SIMATIC%20libcurl%20%28Update%20B%29&body=www.cisa.gov/news-events/ics-advisories/icsa-21-068-10
7.5 High
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
8.8 High
AI Score
Confidence
High
5 Medium
CVSS2
Access Vector
NETWORK
Access Complexity
LOW
Authentication
NONE
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
PARTIAL
AV:N/AC:L/Au:N/C:N/I:N/A:P
0.004 Low
EPSS
Percentile
73.5%