OVERVIEW This advisory was originally posted to the US-CERT secure portal library on January 06, 2014, and is now being released to the NCCIC/ICS-CERT Web site Adam Crain of Automatak and independent researcher Chris Sistrunk have identified an improper input validation in the Schneider Electric Telvent SAGE 3030 remote terminal unit (RTU). Schneider Electric has produced a patch that mitigates this vulnerability. This vulnerability could be exploited remotely AFFECTED PRODUCTS The following Schneider Electric versions are affected: All versions released prior to December 1, 2013, Telvent SAGE 3030 C3413-500-001D3_P4 (Firmware from 2010), and Telvent SAGE 3030 C3413-500-001F0_PB (Latest Firmware). IMPACT Successful exploitation of this vulnerability could allow an attacker to affect the availability of the DNP3 master-slave communication in Telvent SAGE 3030 devices. 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 Schneider Electric is a European-based company that maintains offices in 190 countries worldwide. The affected products, Telvent SAGE 3030 RTUs, are industrial data communications devices. According to Schneider Electric, these products are deployed across several sectors including the energy sector. Schneider Electric estimates that these products are used primarily in the United States and North America. VULNERABILITY CHARACTERIZATION VULNERABILITY OVERVIEW IMPROPER INPUT VALIDATIONa The DNP3 service in Telvent SAGE RTUs incorrectly validates some malformed input. Successful exploitation of this vulnerability disables communications and induces high system load for a short period of time (as in a denial-of-service attack). CVE-2013-6143b has been assigned to this vulnerability. A CVSS v2 base score of 4.3 has been assigned; the CVSS vector string is (AV:N/AC:M/Au:N/C:N/I:N/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 low skill would be able to exploit this vulnerability. MITIGATION Schneider Electric has created a patch to mitigate this vulnerability on the C3414 LX-800-based RTUs using latest VX-works 6.9.3 OS. Customers may obtain this patch by contacting the Schneider Electric Customer Service Department at 713-920-6832. For further information, please find a description and release notes in the Schneider Electric RTU Software Security Bulletin number RTUSW 13001 “Schneider Electric Telvent SAGE RTU DNP3 Improper Input Validation” published December 30, 2013. A Schneider Electric customer login account is required to access this bulletin. Because this vulnerability is identified with fuzzing tools, the researchers suggest developers use extensive negative testing during quality control of products. The researchers also suggest blocking DNP3 traffic from traversing onto business or corporate networks through the use of an IPS or firewall with DNP3-specific rule sets. NCCIC/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. NCCIC/ICS-CERT also provides a section for control systems security recommended practices on the NCCIC/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. NCCIC/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 NCCIC/ICS-CERT Technical Information Paper, ICS-TIP-12-146-01B—Targeted Cyber Intrusion Mitigation Strategies, that is available for download from the NCCIC/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 NCCIC/ICS-CERT for tracking and correlation against other incidents.