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26 February 2015

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             AUSCERT External Security Bulletin Redistribution

       Software Toolbox Top Server Resource Exhaustion Vulnerability
                             26 February 2015


        AusCERT Security Bulletin Summary

Product:           Software Toolbox Top Server
Publisher:         US-CERT
Operating System:  Windows
Impact/Access:     Denial of Service -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2014-5425  

Reference:         ESB-2015.0456

Original Bulletin: 

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Advisory (ICSA-15-055-01)

Software Toolbox Top Server Resource Exhaustion Vulnerability

Original release date: February 24, 2015

Legal Notice

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Adam Crain of Automatak and Chris Sistrunk of Mandiant have identified a 
resource exhaustion vulnerability in the Software Toolbox Top Server 
application. Software Toolbox has produced a new version that mitigates this 

This vulnerability could be exploited remotely.


The following Software Toolbox Top Server versions are affected:

    Software Toolbox Top Server Versions 5.16 and earlier.


An attacker who exploits this response processing vulnerability may be able to
crash the OPC Server application software running on the target.

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.


Software Toolbox is a US-based company that maintains offices primarily in 
Matthews, North Carolina. The TOP Server application is used as an industrial
third-party connectivity communication software for OPC and embedded device 
communication users, system integrators, and in OEM automated processes 

The affected product, Top Server, is a Microsoft Windows-based software that 
facilitates connectivity to multiple DNP3 compliant devices such as HMI, RTU,
PLC, sensors and meters.

According to Software Toolbox, Top Server is deployed worldwide across several
sectors including Chemical, Commercial Facilities, Critical Manufacturing, 
Energy, Food and Agriculture, Information Technology, and Water and Wastewater




A vague interpretation of the DNP3 protocol may allow a specially crafted 
response to create large numbers of entries in the master in some 
implementations. This is not a universal problem for all DNP3 users, vendors,
or integrators, but it may occur.

CVE-2014-5425[b] has been assigned to this vulnerability. A CVSS v2 base score 
of 7.5 has been assigned; the CVSS vector string is 



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.


Remote devices should not return a variation of 0 to a master, and a master 
that encounters a zero length message from a remote should stop processing 
that message.

DNP3 Application Note AN2013-004b Validation of Incoming DNP3 Data, published
August 13, 2014, addresses this issue. This bulletin may be downloaded at:


Software Toolbox has produced a new version of Top Server software, 
V5.17.495.0, which resolves the vulnerability. Information about the new 
version is available at the Software Toolbox support site:


Telephone support is available to trial and registered users 8 a.m. to 5 p.m.
US Eastern Time (GMT5), Monday through Friday.

US Toll Free 1-888-665-3678

Global 1-704-849-2773

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 ICSCERT Technical Information Paper, 
ICS-TIP-12-146-01BTargeted Cyber Intrusion Mitigation Strategies, that is 
available for download from the ICS-CERT web site 

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.

a. CWE-400: Uncontrolled Resource Consumption ('Resource Exhaustion'), 
http://cwe.mitre.org/data/definitions/400.html, web site last accessed 
February 24, 2015.

b. NVD, http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2014-5425, web
site last accessed February 24, 2015.

c. CVSS Calculator, 
http://nvd.nist.gov/cvss.cfm?version=2&vector=AV:N/AC:L/Au:N/C:P/I:P/A:P, web
site last accessed February 24, 2015.

Contact Information

For any questions related to this report, please contact ICS-CERT at:

Email: ics-cert@hq.dhs.gov

Toll Free: 1-877-776-7585

International Callers: (208) 526-0900

For industrial control systems security information and incident reporting: 

ICS-CERT continuously strives to improve its products and services. You can 
help by choosing one of the links below to provide feedback about this 

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