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ICS-CERT has received a report from Siemens regarding a buffer overflow vulnerability in the web interface of the Scalance X Industrial Ethernet switch. This vulnerability was reported to Siemens by Jürgen Bilberger from Daimler TSS GmbH.
This vulnerability leaves the affected devices susceptible to a remote denial of service attack. Siemens has published a firmware update that addresses this vulnerability.
The following Scalance X products affected by this vulnerability:
- Scalance X414-3E
- Scalance X308-2M
- Scalance X-300EEC
- Scalance XR-300
- Scalance X-300
Successful exploitation of the reported vulnerability allows an attacker to perform malicious actions which may lead to a denial of service condition or possible arbitrary code execution. These actions may ultimately impact the process environment in which the system is deployed.
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.
Scalance X Industrial Ethernet switches are industrial grade Ethernet switches used to connect industrial components. This product line provides a web interface to manage controller configuration. Scalance X is used in the Agriculture and Food, Critical Manufacturing, Government Facilities, Dams, Transportation Systems, Water, Chemical, Defense Industrial Base, Energy, and Communications sectors.
The embedded web server does not properly sanitize URLs in HTTP requests. If an attacker requests a malformed URL from the web server, a vulnerable Scalance X switch reboots, inhibits further data transmission to the switch, and may allow arbitrary code execution.
CVE-2012-1802 has been assigned to this vulnerability. Siemens has assigned a CVSS V2 base score of 7.8.
This vulnerability is remotely exploitable.
Existence of Exploit
No known exploits specifically target this vulnerability.
An attacker with a moderate skill level would be able to exploit these vulnerabilities.
Siemens has produced firmware updates that resolve this vulnerability for the listed hardware platforms. Siemens strongly recommends installing the updates as soon as possible. Download the appropriate update from the following links:
- Firmware Update Location (Scalance X414-3E)
- Firmware Update Location (Scalance X308-2M, X-300EEC, XR-300, X-300)
- an overview over the Operational Guidelines for Industrial Security (with the cell protection concept)
- Information about industrial security by Siemens
- Recommended security practices by US-CERT
- For further inquiries on vulnerabilities in Siemens products and solutions, please contact the Siemens Product CERT
The Siemens Security Advisory is available at http://www.siemens.com/corporate-technology/pool/de/forschungsfelder/siemens_security_advisory_ssa-130874.pdf.
In addition to applying the update provided by Siemens, 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.
The Control Systems Security Program (CSSP) also provides a section for control systems security recommended practices on the CSSP web page. Several recommended practices are available for reading and download, including Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies.
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.
- 1. http://cwe.mitre.org/data/definitions/119.html, CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer, website last accessed April 11, 2012.
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