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AUSCERT External Security Bulletin Redistribution
ESB-2021.3827
Advisory (icsa-21-313-06) OSIsoft PI Web API
10 November 2021
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AusCERT Security Bulletin Summary
---------------------------------
Product: OSIsoft PI Web API
Publisher: ICS-CERT
Operating System: Windows
Impact/Access: Provide Misleading Information -- Existing Account
Access Confidential Data -- Existing Account
Resolution: Patch/Upgrade
CVE Names: CVE-2021-3093
Original Bulletin:
https://us-cert.cisa.gov/ics/advisories/icsa-21-313-06
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ICS Advisory (ICSA-21-313-06)
OSIsoft PI Web API
Original release date: November 09, 2021
Legal Notice
All information products included in https://us-cert.cisa.gov/ics are provided
"as is" for informational purposes only. The Department of Homeland Security
(DHS) does not provide any warranties of any kind regarding any information
contained within. DHS does not endorse any commercial product or service,
referenced in this product or otherwise. Further dissemination of this product
is governed by the Traffic Light Protocol (TLP) marking in the header. For more
information about TLP, see https://us-cert.cisa.gov/tlp/ .
1. EXECUTIVE SUMMARY
o CVSS v3 6.9
o ATTENTION: Exploitable remotely/low attack complexity
o Vendor: OSIsoft
o Equipment: PI Web API
o Vulnerability: Cross-site Scripting
2. RISK EVALUATION
Successful exploitation of this vulnerability could allow a remote
authenticated attacker access to sensitive information or deliver false
information.
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
The following versions of PI Web API, a data management platform, are affected:
o All versions of PI Web API 2019 SPI and prior
3.2 VULNERABILITY OVERVIEW
3.2.1 IMPROPER NEUTRALIZATION OF INPUT DURING WEB PAGE GENERATION ('CROSS-SITE
SCRIPTING') CWE-79
A remote authenticated attacker with write access to a PI Server could trick a
user into interacting with a PI Web API endpoint and redirect them to a
malicious website. As a result, a victim may disclose sensitive information to
the attacker or be provided with false information.
CVE-2021-3093 has been assigned to this vulnerability. A CVSS v3 base score of
6.9 has been calculated; the CVSS vector string is ( AV:N/AC:L/PR:H/UI:R/S:C/
C:H/I:L/A:N) .
3.3 BACKGROUND
o CRITICAL INFRASTRUCTURE SECTORS: Multiple Sectors
o COUNTRIES/AREAS DEPLOYED: Worldwide
o COMPANY HEADQUARTERS LOCATION: United States
3.4 RESEARCHER
OSIsoft reported this vulnerability to CISA.
4. MITIGATIONS
OSIsoft recommends upgrading to PI Web API 2021. Additional information can be
found in the OSIsoft PI Web API security bulletin (registration required).
OSIsoft recommends applying the following workaround in PI Web API to help
reduce the risk:
Remove the OSIsoft.REST.Documentation.dll from the PI Web API installation
directory.
o The PI Web API installation directory is available at this registry entry:
\\HKLM\SOFTWARE\PISystem\WebAPI\InstallationDirectory
o The default PI Web API installation directory is:
C:\Program Files\PIPC\WebAPI
Removing this file will cause built-in documentation to no longer be
available. Navigating to the PI Web API endpoint with a browser will
result in an error; however, the PI Web API will continue to function
as a REST API
o Documentation can be found at the OSIsoft website . Alternately, users are
encouraged to limit access to PI Web API built-in documentation to
dedicated development environments
OSIsoft recommends users employ the following defense measures to lower the
impact of exploitation for PI Web API:
o Avoid adding authentication type "Anonymous" in PI Web API configuration
settings to limit exposure to authenticated users only,
o Consider using a web application firewall to block html responses from PI
Web API servers,
o Audit the AF hierarchy to ensure there are no unauthorized databases,
elements, or attributes,
o For Kerberos authentication configurations, use Group Policy to deny
network authentication to PI Server Administrator accounts on the PI Web
API server.
See the OSIsoft customer portal knowledge article for additional details and
associated security updates (registration required).
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.
CISA also recommends users take the following measures to protect themselves
from social engineering attacks:
o Do not click web links or open unsolicited attachments in email messages.
o Refer to Recognizing and Avoiding Email Scams for more information on
avoiding email scams.
o Refer to Avoiding Social Engineering and Phishing Attacks for more
information on social engineering attacks.
No known public exploits specifically target this vulnerability.
For any questions related to this report, please contact the CISA at:
Email: CISAservicedesk@cisa.dhs.gov
Toll Free: 1-888-282-0870
CISA continuously strives to improve its products and services. You can help by
choosing one of the links below to provide feedback about this product.
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