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Advisory (ICSA-16-175-02)

Unitronics VisiLogic OPLC IDE vlp File Parsing Stack Buffer Overflow Vulnerability

Original release date: June 23, 2016

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ZDI has identified a buffer overflow vulnerability discovered by Steven Seeley of Source Incite in Unitronics VisiLogic. Unitronics has produced a new version to mitigate this vulnerability.

This vulnerability could be exploited remotely.


Unitronics reports that the vulnerability affects the following versions of VisiLogic:

  • Visilogic prior to Version 9.8.30


By exploiting this vulnerability, an attacker may be able to remotely 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.


Unitronics has offices in the United States and Israel.

The affected product, Unitronics VisiLogic OPLC IDE, is an HMI and PLC application programming environment for Vision and SAMBA series controllers. According to Unitronics, this product is used worldwide in multiple sectors.




The failure is caused by an attempt to copy into a fixed-length stack buffer without validating its length.

CVE-2016-4519b has been assigned to this vulnerability. A CVSS v3 base score of 7.3 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L).c



This vulnerability could be exploited remotely.


No known public exploits specifically target this vulnerability.


An attacker with a low skill would be able to exploit this vulnerability.


Unitronics recommends that users upgrade to Visilogic Version 9.8.30 or later to mitigate this vulnerability. 

The latest version can be found on the Unitronics web site at the following location:


ICS-CERT recommends that users take defensive measures to minimize the risk of exploitation of these vulnerabilities. Specifically, users should:

  • 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 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.

Contact Information

For any questions related to this report, please contact the NCCIC at:

Toll Free: 1-888-282-0870

For industrial control systems cybersecurity information:  http://ics-cert.us-cert.gov 
or incident reporting:  https://ics-cert.us-cert.gov/Report-Incident?

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