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AUSCERT External Security Bulletin Redistribution
ESB-2012.0396
ICSA-12-102-05 Siemens Scalance S Security Modules Multiple Vulnerabilities
20 April 2012
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AusCERT Security Bulletin Summary
---------------------------------
Product: Scalance S602 V2
Scalance S612 V2
Scalance S613 V2
Publisher: US-CERT
Operating System: Network Appliance
Impact/Access: Execute Arbitrary Code/Commands -- Remote/Unauthenticated
Denial of Service -- Remote/Unauthenticated
Reduced Security -- Remote/Unauthenticated
Resolution: Patch/Upgrade
CVE Names: CVE-2012-1800 CVE-2012-1799
Original Bulletin:
http://www.us-cert.gov/control_systems/pdf/ICSA-12-102-05.pdf
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ICS-CERT ADVISORY
ICSA-12-102-05 SIEMENS SCALANCE S SECURITY MODULES MULTIPLE VULNERABILITIES
April 11, 2012
OVERVIEW
ICS-CERT has received a report from Siemens regarding two security
vulnerabilities in the s 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.
AFFECTED PRODUCTS
The following Scalance S Security Modules are affected:
Scalance S602 V2
Scalance S612 V2
Scalance S613 V2
IMPACT
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.
BACKGROUND
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.
VULNERABILITY CHARACTERIZATION
VULNERABILITY OVERVIEW
BRUTE-FORCE VULNERABILITY a
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 has been assigned to this vulnerability. A CVSS V2 base
score of 10.0 has also been assigned. b
STACK-BASED OVERFLOW c
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 has been assigned to this vulnerability. Siemens has
assigned a CVSS V2 base score of 6.1. d
VULNERABILITY DETAILS
EXPLOITABILITY
These vulnerabilities are remotely exploitable.
a. http://cwe.mitre.org/data/definitions/307.html, CWE-307: Improper
Restriction of Excessive Authentication Attempts, website last accessed
April 11, 2012
b. http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2012-1799, NIST
uses this advisory to create the CVE website report. This website will be
active sometime after publication of this advisory.
c. http://cwe.mitre.org/data/definitions/121.html , CWE-1121: Stack-based
buffer Overflow, website last accessed April 11, 2012
d. http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2012-1800, NIST uses
this advisory to create the CVE website report. This website will be active
sometime after publication of this advisory.
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.
MITIGATION
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
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. ICS-CERT reminds
organizations to perform proper impact analysis and risk assessment prior to
taking defensive measures.
e. CSSP Recommended Practices, http://www.us-cert.gov/control_systems/practices/Recommended_Practices.html, website last accessed April 11, 2012.
ICS-CERT CONTACT
For any questions related to this report, please contact ICS-CERT at:
E-mail: ics-cert@dhs.gov Toll Free: 1-877-776-7585 For CSSP Information and
Incident Reporting: www.ics-cert.org
DOCUMENT FAQ
What is an ICS-CERT Advisory? An ICS-CERT Advisory is intended to provide
awareness or solicit feedback from critical infrastructure owners and
operators concerning ongoing cyber events or activity with the potential to
impact critical infrastructure computing networks.
When is vulnerability attribution provided to researchers? Attribution for
vulnerability discovery is always provided to the vulnerability reporter
unless the reporter notifies ICS-CERT that they wish to remain anonymous.
ICS-CERT encourages researchers to coordinate vulnerability details before
public release. The public release of vulnerability details prior to the
development of proper mitigations may put industrial control systems and the
public at avoidable risk.
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