SUBNET Solutions Inc. SubSTATION Server DNP3 Outstation Improper Input Validation

OVERVIEW

Adam Crain of Automatak and independent researcher Chris Sistrunk have identified an improper input validation in the SUBNET Solutions Inc. SubSTATION Server software application. SUBNET Solutions Inc. has produced a new version that mitigates this vulnerability. SUBNET Solutions Inc. has tested the new version to validate that it resolves the vulnerability.

This vulnerability could be exploited remotely.

AFFECTED PRODUCTS

The following SUBNET Solutions Inc. products are affected:

• SubSTATION Server v2.7.0033, and
• SubSTATION Server v2.8.0106.

IMPACT

Successful exploitation of this vulnerability could allow an attacker to affect the availability of the DNP3 Slave service in the SUBNET Solutions Inc. SubSTATION Server software.

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.

BACKGROUND

SUBNET Solutions Inc. is a Canada-based company that maintains offices in Canada and the US.

The affected product, SubSTATION Server, is a substation communication server deployed across the energy sector worldwide.

VULNERABILITY CHARACTERIZATION

VULNERABILITY OVERVIEW

IMPROPER INPUT VALIDATIONCWE-20: Improper Input Validation, http://cwe.mitre.org/data/definitions/20.html, Web site last accessed September 09, 2013.

The DNP3 Slave service in SUBNET Solutions Inc. SubSTATION Server does not validate or incorrectly validates input. An attacker could introduce an unhandled exception, causing the process to crash. If settings are configured to automatically restart, the DNP3 Slave service will automatically restart and resume communications. Otherwise, the system must be restarted manually.

CVE-2013-2788NVD, http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2013-2788, NIST uses this advisory to create the CVE Web site report. This Web site will be active sometime after publication of this advisory. has been assigned to this vulnerability. A CVSS v2 base score of 7.1 has been assigned; the CVSS vector string is (AV:N/AC:M/Au:N/C:N/I:N/A:C).CVSS Calculator, http://nvd.nist.gov/cvss.cfm?version=2&vector=AV:N/AC:M/Au:N/C:N/I:N/A:C, Web site last accessed September 09, 2013.

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

SUBNET Solutions Inc. has produced a new version of SubSTATION Server that is available for download. To arrange access to a secure download of the updated version, please contact SUBNET Solutions Inc. Technical Services by e-mail at support@subnet.com or by phone at 403-270-8885 Monday through Friday from 9 am to 5 pm Mountain time.

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.CSSP Recommended Practices, http://ics-cert.us-cert.gov/content/recommended-practices, Web site last accessed September 09, 2013. 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 Mitigation Strategies,Targeted Cyber Intrusion Detection and Mitigation Strategies, http://ics-cert.us-cert.gov/tips/ICS-TIP-12-146-01B, Web site last accessed September 09, 2013. that is available for download from the ICS-CERT Web page (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.

• SUBNET Solutions Inc.