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AUSCERT External Security Bulletin Redistribution
ESB-2015.0459
Software Toolbox Top Server Resource Exhaustion Vulnerability
26 February 2015
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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:
https://ics-cert.us-cert.gov/advisories/ICSA-15-055-01
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Advisory (ICSA-15-055-01)
Software Toolbox Top Server Resource Exhaustion Vulnerability
Original release date: February 24, 2015
Legal Notice
All information products included in http://ics-cert.us-cert.gov are provided
"as is" for informational purposes only. The Department of Homeland Security
(DHS) does not provide any warranties of any kind regarding any information
contained within. DHS does not endorse any commercial product or service,
referenced in this product or otherwise. Further dissemination of this product
is governed by the Traffic Light Protocol (TLP) marking in the header. For
more information about TLP, see http://www.us-cert.gov/tlp/.
OVERVIEW
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
vulnerability.
This vulnerability could be exploited remotely.
AFFECTED PRODUCTS
The following Software Toolbox Top Server versions are affected:
Software Toolbox Top Server Versions 5.16 and earlier.
IMPACT
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.
BACKGROUND
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
worldwide.
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
Systems.
VULNERABILITY CHARACTERIZATION
VULNERABILITY OVERVIEW
UNCONTROLLED RESOURCE CONSUMPTION (RESOURCE EXHAUSTION)[a]
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
(AV:N/AC:L/Au:N/C:P/I:P/A:P).[c]
VULNERABILITY DETAILS
EXPLOITABILITY
This vulnerability could be exploited remotely.
EXISTENCE OF EXPLOIT
No known public exploits specifically target this vulnerability.
DIFFICULTY
An attacker with a moderate skill would be able to exploit this vulnerability.
MITIGATION
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:
https://www.dnp.org/DNP3Downloads/AN2013-004b%20Validation%20of%20Incoming%20DNP3%20Data.pdf)
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:
http://www.toolboxopc.com/html/support.asp
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
(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.
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:
http://ics-cert.us-cert.gov
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
product.
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