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This advisory was originally posted to the US-CERT secure Portal library on March 08, 2013, and is now being released to the ICS-CERT Web page.
This advisory provides mitigation details for a vulnerability that impacts the Invensys Wonderware Win-XML Exporter.
Researchers Timur Yunusov, Alexey Osipov, and Ilya Karpov of the Positive Technologies Research Team have discovered an improper input validation vulnerability in the Invensys Wonderware Win-XML Exporter. Invensys has released a patch that mitigates the vulnerability. The Positive Technologies Research Team has validated that the patch fixes the vulnerability. Exploitation of this vulnerability could impact systems deployed in the critical manufacturing, energy, food and beverage, chemical, and water and wastewater sectors.
The following Invensys Wonderware products are affected:
- Win-XML Exporter Version 1522, 148, 0, 0, and possibly earlier versions.
Successful exploitation of this vulnerability could allow an attacker to affect the confidentiality and availability of the Wonderware Win-XML Exporter.
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.
Invensys is a global technology company that works with industrial, commercial, rail operators, and appliance operators, while operating in over 180 countries. Invensys develops software, systems, and equipment that enable users to monitor, automate, and control their processes.
The Invensys Wonderware Win-XML Exporter is used in many industries worldwide, including critical manufacturing, energy, food and beverage, chemical, and water and wastewater.
The Wonderware Win-XML Exporter converts interface windows from Intouch HMI projects and displays them in Internet Explorer with the help of Wonderware Information Server.
Improper Input Validation1
Wonderware Win-XML Exporter allows access to local resources (files and internal resources) via unsafe parsing of XML external entities. By using specially crafted XML files, an attacker can cause Wonderware Win-XML Exporter to send the contents of local or remote resources to the attacker’s server or cause a denial of service of the system.
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 XML files.
Existence of Exploit
No known public exploits specifically target this vulnerability.
An attacker with a medium skill would be able to exploit this vulnerability.
Invensys has developed an update to the Win-XML Exporter that mitigates this vulnerability. The Positive Technologies Research Team has tested the update and validated that it fixes the vulnerability. Instructions and a link to the update are found on the Invensys download page.
According to Invensys, any machine running one or more of the products listed above is affected and should be patched. No other components of the Wonderware installed products are affected. Users should install the update using instructions provided in the ReadMe file for the product and component being installed. Invensys recommends that users:
- Read the installation instructions provided with the patch.
- Shut down any of the affected software products.
- Install the update.
- Restart the software.
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. Critical devices should not directly face 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 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. 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 taking 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.
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.
- 1. CWE-20 Improper Input Validation, http://cwe.mitre.org/data/definitions/20.html, Web site last accessed March 21, 2013.
- 2. NVD, http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2012-4710, NIST uses this advisory to create the CVE Web site report. This Web site will be active sometime after publication of this advisory.
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