Siemens Fixes Communication Processor

Tuesday, December 1, 2015 @ 05:12 PM gHale

Siemens created a firmware update for an authentication bypass vulnerability in its SIMATIC Communication Processor devices CP 343-1, TIM 3V-IE, TIM 4R-IE, and CP 443-1, according to a report on ICS-CERT.

The remotely exploitable vulnerability ended up reported directly to Siemens by Lei ChengLin (Z-0ne) from the Fengtai Technologies’ Security Research Team.

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The following Communication Processor modules, designed for use with Siemens’ SIMATIC S7-300/S7-400 CPUs, suffer from the issue:
• SIMATIC CP 343-1 Advanced: All firmware versions prior to V3.0.44
• SIMATIC CP 343-1 Lean / CP 343-1: All firmware versions
• SIMATIC TIM 3V-IE / 3V-IE Advanced: All firmware versions
• SIMATIC TIM 3V-IE DNP3: All firmware versions
• SIMATIC TIM 4R-IE: All firmware versions
• SIMATIC TIM 4R-IE DNP3: All firmware versions
• SIMATIC CP 443-1 / CP 443-1 Advanced: All firmware versions

Successful exploitation of this vulnerability may allow unauthenticated users to perform administrative operations on the SIMATIC Communication Processor under certain conditions.

Munich, Germany-based Siemens is a multinational company.

The affected products, Siemens SIMATIC Communication Processor module families, enable SIMATIC S7-300/S7-400 CPUs for Ethernet or Telecontrol communication. Siemens estimates these products see use on a global basis.

Communication Processor module families may allow unauthenticated users to perform administrative operations on the Communication Processor if network access to Port 102/TCP is available and the Communication Processor’s configuration ends up stored on its corresponding CPUs.

CVE-2015-8214 is the case number assigned to this vulnerability, which has a CVSS v3 base score of 9.4.

No known public exploits specifically target this vulnerability. However, an attacker with a low skill would be able to exploit this vulnerability.

Siemens released a firmware update, V3.0.44, for SIMATIC CP 343-1 Advanced modules and is working on firmware updates for the remaining affected products. Siemens recommends customers update to the new firmware update, V3.0.44.

Siemens also recommends applying the following mitigations in the meantime:
• Activate firewall functionality on Advanced-Communication Processor and reject S7-communication at the perimeter port
• Apply cell protection concept, described in this URL
• Use VPN for protecting network communication between cells
• Apply Defense-in-Depth, described in this URL
Siemens has also identified the following conditions that must exist for an attacker to exploit the vulnerability:
• Network access to the affected devices
• Configuration data for the CP must be stored on CPU
• Firewall functionality of Advanced-CPs must be turned off for Port 102/TCP

For more information on this vulnerability and detailed instructions, please see Siemens Security Advisory SSA-763427.

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