Advantech WebAccess Stack-based Buffer Overflow
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Ricardo Narvaja from Core Security Consulting Services discovered and disclosed information regarding a buffer overflow vulnerabilitya in Advantech WebAccess. Joaquín Rodríguez Varela from the Core Advisories Team reported this to NCCIC/ICS-CERT, who coordinated with Advantech. Advantech has produced a new version of WebAccess that does not have this vulnerability when installed on a machine that did not have a previous version of WebAccess.
The following Advantech WebAccess versions are affected:
- WebAccess 7.2 and previous.
An attacker exploiting this vulnerability may have the ability to execute arbitrary code on the target system.
Impact to individual organizations depends on many factors that are unique to each organization. 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.
Advantech WebAccess, formerly known as BroadWin WebAccess, is a web-based SCADA and human-machine interface product deployed across several sectors including Energy, Critical Manufacturing, Commercial Facilities, and Government Facilities. These systems are deployed globally.
STACK-BASED BUFFER OVERFLOWb
This vulnerability is caused by a stack buffer overflow when parsing the ip_address parameter. A malicious third party could trigger execution of arbitrary code within the context of the application or otherwise crash the whole application. This is caused because the application copies strings to the stack without checking length.
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 html file.
EXISTENCE OF EXPLOIT
No known public exploits specifically target this vulnerability.
An attacker with a low skill would be able to exploit this vulnerability.
Advantech has created a new version (8.0) to mitigate this vulnerability. Users may download the patch from the following location at Advantech’s web site:
For additional information about WebAccess, please visit the following Advantech web site:
Core Security recommends that if users upgrade to WebAccess 8.0, they must also delete the vulnerable “webeye.ocx” from their system, or uninstall the previous version before installing WebAccess 8.0. It recommends that users avoid opening untrusted .html files. Core Security also recommends the use of third-party software to help prevent the exploitation of affected systems.
ICS-CERT encourages asset owners to take additional defensive measures to protect against this and other cybersecurity risks.
- Minimize network exposure for all control system devices and/or systems, and ensure that they are not accessible from the Internet.
- Locate control system networks and remote devices behind firewalls, and isolate them from the business network.
- When remote access is required, use secure methods, such as Virtual Private Networks (VPNs), recognizing that VPNs may have vulnerabilities and should be updated to the most current version available. Also recognize that VPN is only as secure as the connected devices.
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/).
In addition, ICS-CERT recommends that users take the following measures to protect themselves from social engineering attacks:
- Do not click web links or open unsolicited attachments in email messages.
- Refer to Recognizing and Avoiding Email Scamse for more information on avoiding email scams.
- Refer to Avoiding Social Engineering and Phishing Attacksf for more information on social engineering attacks.
- a. Core Security Advantech WebAccess Stack-based Buffer Overflow, http://www.coresecurity.com/advisories/advantech-webaccess-stack-based-b... web site last accessed November 20, 2014.
- b. CWE-121: Stack-based Buffer Overflow, http://cwe.mitre.org/data/definitions/121.html, web site last accessed November 20, 2014.
- c. NVD, http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2014-8388, NIST uses this advisory to create the CVE web site report. This web site will be active sometime after publication of this advisory.
- d. CVSS Calculator, http://nvd.nist.gov/cvss.cfm?version=2&vector=AV:L/AC:L/Au:N/C:C/I:C/A:C, web site last accessed November 20, 2014.
- e. Recognizing and Avoiding Email Scams, http://www.us-cert.gov/reading_room/emailscams_0905.pdf, web site last accessed November 20, 2014.
- f. National Cyber Alert System Cyber Security Tip ST04-014, http://www.us-cert.gov/cas/tips/ST04-014.html, web site last accessed November 20, 2014.
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