Advantech WebAccess ActiveX Vulnerabilities (Update A)
ICSA： ICS Advisory (ICSA-16-173-01A)
This updated advisory is a follow-up to the original advisory titled ICSA-16-173-01 Advantech WebAccess ActiveX Vulnerabilities that was published June 21, 2016, on the NCCIC/ICS-CERT web site.
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Zhou Yu of Acorn Network Security and ZDI (Zero Day Initiative) have identified vulnerabilities in Advantech’s 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.
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Advantech reports that the vulnerabilities affect the following versions of WebAccess:
- WebAccess versions prior to 8.1_20160519
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.
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.
UNSAFE ACTIVEX CONTROL MARKED SAFE-FOR-SCRIPTINGa
Several ActiveX controls are intended for restricted use, but have been marked as safe-for-scripting.
CLASSIC BUFFER OVERFLOWd
A specially crafted DLL file can cause a buffer overflow.
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A properly authenticated administrator can view passwords for other administrators.
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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.
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.
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:
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 ICS‑CERT 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:U/C:H/I:H/A:N, 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:U/C:N/I:N/A:H, web site last accessed June 21, 2016.
- g. a. b. CWE-200: Information Exposure, http://cwe.mitre.org/data/definitions/200.html, web site last accessed July 14, 2016.
- h. a. b. NVD, http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2016-5810, NIST uses this advisory to create the CVE web site report. This web site will be active sometime after publication of this advisory.
- i. CVSS Calculator, https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N, web site last accessed July 14, 2016.