Ivan Sanchez from Nullcode Team has identified a stack-based buffer overflow vulnerability in Advantech’s WebAccess application. Advantech has produced a new version to mitigate this vulnerability. Ivan Sanchez has tested the new version to validate that it resolves the vulnerability.
The following WebAccess versions are affected:
• WebAccess Version 8.0 and prior versions.
An attacker may be able to exploit this vulnerability to crash the WebAccess application or to execute arbitrary code.
Impact to individual organizations depends on many factors that are unique to each organization. NCCIC/ICS-CERT recommends that organizations evaluate the impact of this vulnerability 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 product. According to Advantech, WebAccess is deployed across several sectors including Commercial Facilities, Critical Manufacturing, Energy, and Government Facilities. Advantech estimates that these products are used globally.
A specially crafted file could be used to overflow the stack buffer by providing overly long strings to functions in the affected DLL. An attacker may then be able to crash the application or run arbitrary code by getting a user to execute the specially crafted file.
CVE-2014-9202b has been assigned to this vulnerability. A CVSS v2 base score of 6.9 has been assigned; the CVSS vector string is (AV:L/AC:M/Au:N/C:C/I:C/A:C).c
This vulnerability is not exploitable remotely and cannot be exploited without user interaction. The exploit is only triggered when a local user runs the vulnerable application and loads the malformed file.
No known public exploits specifically target this vulnerability.
Crafting a working exploit for this vulnerability would be difficult. Social engineering is required to convince the user to load the malformed file. This decreases the likelihood of a successful exploit.
Advantech has released a new version of WebAccess, Version 8.0_20150816, which addresses the reported vulnerability. WebAccess, Version 8.0_20150816, is available at the following URL:
ICS-CERT encourages asset owners to take additional defensive measures to protect against this and other cybersecurity risks.
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. ICS-CERT reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures.
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.