10 High
CVSS2
Attack Vector
NETWORK
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
COMPLETE
Integrity Impact
COMPLETE
Availability Impact
COMPLETE
AV:N/AC:L/Au:N/C:C/I:C/A:C
10 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
10 High
AI Score
Confidence
High
0.003 Low
EPSS
Percentile
71.3%
Successful exploitation of this vulnerability could allow a remote unauthenticated attacker to execute code on the affected system with root privileges.
Siemens reports the vulnerability affects the following Siveillance OIS Building Management Systems products:
The affected application incorrectly neutralizes special elements in a specific HTTP GET request, which could lead to command injection. An unauthenticated remote attacker could exploit this vulnerability to execute arbitrary code on the system with root privileges.
CVE-2021-31891 has been assigned to this vulnerability. A CVSS v3 base score of 10.0 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H).
Siemens reported this vulnerability to CISA.
Siemens has released patches and updates for Siveillance OIS to apply to the products that incorporate the OIS service. Siemens recommends updating the OIS to the latest version v2.5.3 or applying the patch
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 affected products with appropriate mechanisms. Users are advised to follow recommended security practices in order to run the devices in a protected IT environment.
For more information, please see Siemens Security Advisory SSA-535380
CISA recommends users take defensive measures to minimize the risk of exploitation of these vulnerabilities. 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-2021-31891
cert-portal.siemens.com/productcert/pdf/ssa-535380.pdf
cwe.mitre.org/data/definitions/78.html
public.govdelivery.com/accounts/USDHSCISA/subscriber/new?topic_id=USDHSCISA_138
support.industry.siemens.com/cs/ww/en/view/109799908/
twitter.com/CISAgov
twitter.com/intent/tweet?text=Siemens%20Siveillance%20OIS+https://www.cisa.gov/news-events/ics-advisories/icsa-21-257-18
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
www.facebook.com/sharer/sharer.php?u=https://www.cisa.gov/news-events/ics-advisories/icsa-21-257-18&title=Siemens%20Siveillance%20OIS
www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/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-21-257-18
www.oig.dhs.gov/
www.surveymonkey.com/r/CISA-cyber-survey?product=https://www.cisa.gov/news-events/ics-advisories/icsa-21-257-18
www.usa.gov/
www.whitehouse.gov/
www.youtube.com/@cisagov
mailto:?subject=Siemens%20Siveillance%20OIS&body=www.cisa.gov/news-events/ics-advisories/icsa-21-257-18
10 High
CVSS2
Attack Vector
NETWORK
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
COMPLETE
Integrity Impact
COMPLETE
Availability Impact
COMPLETE
AV:N/AC:L/Au:N/C:C/I:C/A:C
10 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
10 High
AI Score
Confidence
High
0.003 Low
EPSS
Percentile
71.3%