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AUSCERT External Security Bulletin Redistribution
ESB-2016.1575
Advantech WebAccess ActiveX Vulnerabilities
22 June 2016
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AusCERT Security Bulletin Summary
---------------------------------
Product: Advantech WebAccess
Publisher: ICS-CERT
Operating System: Windows
Impact/Access: Execute Arbitrary Code/Commands -- Existing Account
Resolution: Patch/Upgrade
CVE Names: CVE-2016-4528 CVE-2016-4525
Original Bulletin:
https://ics-cert.us-cert.gov/advisories/ICSA-16-173-01
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Advisory (ICSA-16-173-01)
Advantech WebAccess ActiveX Vulnerabilities
Original release date: June 21, 2016
Legal Notice
All information products included in http://ics-cert.us-cert.gov 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 http://www.us-cert.gov/tlp/.
OVERVIEW
Zhou Yu of Acorn Network Security has identified ActiveX vulnerabilities in
Advantech WebAccess. Advantech has produced a new version to mitigate these
vulnerabilities. Zhou Yu has tested the new version to validate that it
resolves the vulnerabilities.
AFFECTED PRODUCTS
Advantech reports that the vulnerabilities affect the following versions of
WebAccess:
WebAccess versions prior to 8.1_20160519
IMPACT
The vulnerabilities could allow an attacker who successfully exploits them to
insert and run arbitrary code on an affected system.
Impact to individual organizations depends on many factors that are unique to
each organization. NCCIC/ICS-CERT recommends that organizations evaluate the
impact of these vulnerabilities based on their operational environment,
architecture, and product implementation.
BACKGROUND
Advantech is based in Taiwan and has distribution offices in 21 countries
worldwide.
The affected product, WebAccess, formerly known as BroadWin WebAccess, is a
web-based SCADA and human-machine interface (HMI) product. According to
Advantech, WebAccess is deployed across several sectors including Commercial
Facilities, Critical Manufacturing, Energy, and Government Facilities.
Advantech estimates that this product is used globally.
VULNERABILITY CHARACTERIZATION
VULNERABILITY OVERVIEW
UNSAFE ACTIVEX CONTROL MARKED SAFE-FOR-SCRIPTING [a]
Several ActiveX controls are intended for restricted use, but have been marked
as safe-for-scripting.
CVE-2016-4525 [b] has been assigned to these vulnerabilities. A CVSS v3 base
score of 6.6 has been calculated; the CVSS vector string is
(AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N). [c]
CLASSIC BUFFER OVERFLOW [d]
A specially crafted DLL file can cause a buffer overflow.
CVE-2016-4528 [e] has been assigned to these vulnerabilities. A CVSS v3 base
score of 5.0 has been calculated; the CVSS vector string is
(AV:L/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H). [f]
VULNERABILITY DETAILS
EXPLOITABILITY
These vulnerabilities are not exploitable remotely and cannot be exploited
without user interaction. The exploit is only triggered when a local user runs
the vulnerable application, which in certain scenarios can cause it to load a
DLL file from an untrusted source.
EXISTENCE OF EXPLOIT
No known public exploits specifically target these vulnerabilities.
DIFFICULTY
Crafting a working exploit for these vulnerabilities would be difficult.
Social engineering is required to convince the user to accept a malformed DLL
file. Additional user interaction is needed to load the malformed file. This
decreases the likelihood of a successful exploit.
MITIGATION
Advantech has released a new version of WebAccess, Version 8.1_20160519, to
address the reported vulnerabilities. This new version is available on the
Advantech web site at the following location:
http://www.advantech.com/industrial-automation/webaccess (link is external)
ICS-CERT recommends that users take defensive measures to protect themselves
from social engineering attacks. Specifically, users should:
Do not click web links or open unsolicited attachments in email messages.
Refer to Recognizing and Avoiding Email Scamsg for more information on
avoiding email scams.
Refer to Avoiding Social Engineering and Phishing Attacksh for more
information on social engineering attacks.
Do not visit untrusted web sites.
ICS-CERT reminds organizations to perform proper impact analysis and risk
assessment prior to deploying defensive measures.
ICS-CERT also provides a section for control systems security recommended
practices on the ICS-CERT web page at:
http://ics-cert.us-cert.gov/content/recommended-practices. 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 in the ICSCERT Technical Information Paper,
ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation
Strategies, that is available for download from the ICS-CERT web site
(http://ics-cert.us-cert.gov/).
Organizations observing any suspected malicious activity should follow their
established internal procedures and report their findings to ICS-CERT for
tracking and correlation against other incidents.
a. CWE-623: Unsafe ActiveX Control Marked Safe For Scripting,
http://cwe.mitre.org/data/definitions/623.html, web site last accessed June
21, 2016.
b. NVD, http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2016-4525, NIST
uses this advisory to create the CVE web site report. This web site will be
active sometime after publication of this advisory.
c. CVSS Calculator,
https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:L/AC:L/PR:L/UI:R/S...,
web site last accessed June 21, 2016.
d. CWE-120: Buffer Copy without Checking Size of Input ('Classic Buffer
Overflow'), http://cwe.mitre.org/data/definitions/120.html, web site last
accessed June 21, 2016.
e. NVD, http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2016-4528, NIST
uses this advisory to create the CVE web site report. This web site will be
active sometime after publication of this advisory.
f. CVSS Calculator,
https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:L/AC:L/PR:L/UI:R/S...,
web site last accessed June 21, 2016.
g. Recognizing and Avoiding Email Scams,
http://www.us-cert.gov/reading_room/emailscams_0905.pdf, web site last
accessed June 21, 2016.
h. National Cyber Alert System Cyber Security Tip ST04-014,
http://www.us-cert.gov/cas/tips/ST04-014.html, web site last accessed June 21,
2016.
Contact Information
For any questions related to this report, please contact ICS-CERT at:
Email: ics-cert@hq.dhs.gov (link sends e-mail)
Toll Free: 1-877-776-7585
International Callers: (208) 526-0900
For industrial control systems security information and incident reporting:
http://ics-cert.us-cert.gov
ICS-CERT 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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