ICS Advisory

IOServer Out of Bounds Read Vulnerability

Last Revised
Alert Code


Chris Sistrunk of Mandiant and Adam Crain of Automatak have identified an out of bounds read vulnerability in IOServer’s OPC Server application. IOServer has released a new version that mitigates this vulnerability. The researchers have tested the new version to validate that it resolves the vulnerability.

This vulnerability could be exploited remotely.


The following IOServer versions are affected:

  • OPC Drivers Versions 1.0.20 and prior.


An attacker who exploits this out of bounds read vulnerability may be able to crash the OPC Server application software running on the target 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 this vulnerability based on their operational environment, architecture, and product implementation.


IOServer is an Australian company based in Sydney, Australia.

The affected product, OPC Server, is a Windows-based (WindowsNT/95/98/ME/
2000/2003/XP/2008/7) OPC Server that allows OPC clients, such as human-machine interface and supervisory control and data acquisition systems, to exchange plant floor data with programmable logic controllers. According to IOServer, the affected product is deployed across multiple sectors including Commercial Facilities, Critical Manufacturing, Energy, and Water and Wastewaster Systems.



OUT OF BOUNDS READCWE-125: Out of Bounds Read, http://cwe.mitre.org/data/definitions/125.html, web site last accessed April 10, 2014.

The Modbus slave/outstation driver for IOServer’s OPC Server application may be forced to read outside of the intended memory register. By sending a specially crafted packet, an attacker could crash the software. This could significantly interrupt process control.

CVE-2014-0777NVD, http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2014-0777, NIST uses this advisory to create the CVE web site report. This web site will become active some time after publication of this advisory. has been assigned to this vulnerability. A CVSS v2 base score of 8.3 has been assigned; the CVSS vector string is (AV:N/AC:M/Au:N/C:P/I:P/A:C).CVSS Calculator, http://nvd.nist.gov/cvss.cfm?version=2&vector=AV:N/AC:M/Au:N/C:P/I:P/A:C, web site last accessed April 10, 2014.



This vulnerability could be exploited remotely.


No known public exploits specifically target this vulnerability.


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


IOServer has produced a new version that mitigates the vulnerability. The new version, Beta2112.exe, is available for download here:


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 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 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.

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