ICS-CERT: Siemens Scalence S Multiple Vulnerabilities

Thursday, April 12, 2012

Infosec Island Admin


ICS-CERT has received a report from Siemens regarding two security vulnerabilities in the Scalance S Security Module firewall. This vulnerability was reported to Siemens by Adam Hahn and Manimaran Govindarasu for coordinated disclosure.

The first issue is a brute-force credential guessing vulnerability in the web configuration interface of the firewall. The second issue is a stack-based buffer overflow vulnerability in the Profinet DCP protocol stack.

Siemens has published a patch that resolves both of the identified vulnerabilities.

The following Scalance S Security Modules are affected:

• Scalance S602 V2
• Scalance S612 V2
• Scalance S613 V2


Successful exploitation of the brute-force vulnerability may allow an attacker to perform an arbitrary number of authentication attempts using different password and eventually gain access to the targeted account.

Successful exploitation of the stack-based buffer overflow against the Profinet DCP protocol may lead to a denial of service (DoS) condition or possible arbitrary code execution.

Impact to individual organizations depends on many factors that are unique to each organization. ICS-CERT recommends that organizations evaluate the impact of these vulnerabilities based on their operational environment, architecture, and product implementation.


The Scalance S product is a security module that includes a Stateful Inspection Firewall for industrial automation network applications. This security module is intended to protect automation devices and industrial networks against unauthorized access and to secure Ethernet-based industrial communication.

This Siemens product is intended to protect trusted industrial networks from outside facing or untrusted networks. All Scalance S Security Modules provide filtering of incoming and outgoing network connections with stateful packet inspection.

This product is used predominately in Europe and Asia with a small US footprint. The primary sectors deploying Scalance S are Automotive, Defense Industrial Base, Energy, Critical Manufacturing, Transportation Systems, Chemical, and Water.

BRUTE-FORCE VULNERABILITY: The web server in the Scalance S Security Module does not implement sufficient measures to prevent rapid multiple authentication attempts within a short timeframe, making it susceptible to brute-force attacks by attackers with access to the web server. If the administrative password is found, the attacker can manipulate the configuration and gain access to the trusted network. CVE-2012-1799 been assigned to this vulnerability. A CVSS V2 base score of 10.0 has also been assigned.

STACK-BASED OVERFLOW: The Scalance S DCP protocol stack crashes when a specially crafted DCP frame is received, which may renders the firewall unresponsive and interrupts established VPN tunnels. Successful exploitation of this vulnerability may lead to a denial of service (DoS) condition or possible arbitrary code execution. CVE-2012-1800 been assigned to this vulnerability. Siemens has assigned a CVSS V2 base score of 6.1.

EXPLOITABILITY: These vulnerabilities are remotely exploitable.

EXISTENCE OF EXPLOIT: No known exploits specifically target these vulnerabilities.

DIFFICULTY: An attacker with a moderate skill level would be able to exploit these vulnerabilities.


Siemens has published a patch that resolves both of the identified vulnerabilities and strongly recommends installing the updates by using the following links:

• The Siemens Security Advisory is available at: http://www.siemens.com/corporate-technology/pool/de/forschungsfelder/siemens_security_advisory_ssa-268149.pdf

• The firmware update is published on the following web site: http://support.automation.siemens.com/WW/view/en/59869684

• Information about industrial security by Siemens: http://www.siemens.com/industrialsecurity

• Recommended security practices by US-CERT: http://www.us-cert.gov/control_systems/practices/Recommended_Practices.html

• For further inquiries on vulnerabilities in Siemens products and solutions, please contact the Siemens ProductCERT: http://www.siemens.com/cert

The full ICS-CERT advisory can be found here:

Source:  http://www.us-cert.gov/control_systems/pdf/ICSA-12-102-05.pdf

Possibly Related Articles:
Industrial Control Systems
SCADA Vulnerabilities Siemens Buffer Overflow Brute Force Advisory ICS-CERT Industrial Control Systems Scalence S Stack Overflow
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