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             AUSCERT External Security Bulletin Redistribution

                               ESB-2016.2101
          Siemens SIPROTEC 4 and SIPROTEC Compact Vulnerabilities
                             8 September 2016

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        AusCERT Security Bulletin Summary
        ---------------------------------

Product:           Siemens SIPROTEC 4 and SIPROTEC Compact devices
Publisher:         ICS-CERT
Operating System:  Network Appliance
Impact/Access:     Administrator Compromise -- Remote/Unauthenticated
                   Denial of Service        -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2016-7114 CVE-2016-7113 CVE-2016-7112

Original Bulletin: 
   https://ics-cert.us-cert.gov/advisories/ICSA-16-250-01

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Advisory (ICSA-16-250-01)

Siemens SIPROTEC 4 and SIPROTEC Compact Vulnerabilities

Original release date: September 06, 2016

Legal Notice

All information products included in http://ics-cert.us-cert.gov are provided
"as is" for informational purposes only. The Department of Homeland Security 
(DHS) does not provide any warranties of any kind regarding any information 
contained within. DHS does not endorse any commercial product or service, 
referenced in this product or otherwise. Further dissemination of this product
is governed by the Traffic Light Protocol (TLP) marking in the header. For 
more information about TLP, see http://www.us-cert.gov/tlp/.

OVERVIEW

Siemens reports that they have released a firmware update for SIPROTEC 4 and 
SIPROTEC Compact devices to mitigate authentication bypass and resource 
exhaustion vulnerabilities. Kirill Nesterov and Anatoly Katushin from 
Kaspersky Lab reported some of these vulnerabilities directly to Siemens.

These vulnerabilities could be exploited remotely.

AFFECTED PRODUCTS

Siemens reports that these vulnerabilities affect the following products:

EN100 Ethernet module (as optional for SIPROTEC 4 and SIPROTEC Compact): All 
versions prior to V4.29

IMPACT

An attacker may be able to access the administrative web application by 
exploiting these vulnerabilities.

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

BACKGROUND

Siemens is a multinational company headquartered in Munich, Germany.

The affected products, SIPROTEC 4 and SIPROTEC Compact devices, provide a wide
range of integrated protection, control, measurement, and automation functions
for electrical substations and other fields of application. The EN100 module 
is used for enabling IEC 61850 communications with electrical/optical 100 Mbit
interface for SIPROTEC 4 and SIPROTEC Compact devices. According to Siemens, 
SIPROTEC devices are deployed across several sectors including Energy. Siemens
estimates that these products are used worldwide.

VULNERABILITY CHARACTERIZATION

VULNERABILITY OVERVIEW

AUTHENTICATION BYPASS ISSUES [a]

Attackers with network access to the devices web interface (Port 80/TCP) could
possibly circumvent authentication and perform administrative operations.

CVE-2016-7112 [b] has been assigned to this vulnerability. A CVSS v3 base score 
of 5.3 has been calculated; the CVSS vector string is 
(AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N). [c]

RESOURCE EXHAUSTION [d]

Specially crafted packets sent to Port 80/TCP could cause the affected device
to go into defect mode.

CVE-2016-7113 [e] has been assigned to this vulnerability. A CVSS v3 base score 
of 5.3 has been calculated; the CVSS vector string is 
(AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L). [f]

AUTHENTICATION BYPASS ISSUES [g]

Attackers with network access to the devices web interface (Port 80/TCP) could
possibly circumvent authentication and perform administrative operations. A 
legitimate user must be logged into the web interface for the attack to be 
successful.

CVE-2016-7114 [h] has been assigned to this vulnerability. A CVSS v3 base score 
of 4.3 has been calculated; the CVSS vector string is 
(AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N). [i]

VULNERABILITY DETAILS

EXPLOITABILITY

These vulnerabilities could be exploited remotely.

EXISTENCE OF EXPLOIT

No known public exploits specifically target these vulnerabilities.

DIFFICULTY

An attacker with a low skill would be able to exploit these vulnerabilities.

MITIGATION

Siemens provides firmware update V4.29 for EN100 modules included in SIPROTEC
4 and SIPROTEC Compact devices to fix the vulnerabilities. Siemens recommends
users update to the latest firmware version.

The firmware update for SIPROTEC 4 can be obtained from the SIPROTEC 4 
downloads area:

http://www.siemens.com/downloads/siprotec-4 (link is external) (further 
navigation required to select correct update)

The firmware update for SIPROTEC Compact with EN100 module can be obtained 
here:

http://www.siemens.com/downloads/siprotec-compact (link is external) (further
navigation required to select correct update)

For more information on these vulnerabilities and more detailed mitigation 
instructions, please see Siemens Security Advisory SSA-630413 at the following
location:

http://www.siemens.com/cert/advisories (link is external)

ICS-CERT recommends that users take defensive measures to minimize the risk of
exploitation of these vulnerabilities. Specifically, users should:

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 VPNs may have vulnerabilities and should be
updated to the most current version available. Also recognize that VPN is only
as secure as the connected devices.

ICS-CERT reminds organizations to perform proper impact analysis and risk 
assessment prior to deploying defensive measures.

ICS-CERT also provides a section for control systems security recommended 
practices on the 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.

Additional mitigation guidance and recommended practices are publicly 
available in the ICSCERT Technical Information Paper, 
ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation 
Strategies, that is available for download from the 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 ICS-CERT for 
tracking and correlation against other incidents.

a. CWE-592: Authentication Bypass Issues, 
http://cwe.mitre.org/data/definitions/592.html, web site last accessed 
September 6, 2016.

b. NVD, http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2016-7112, NIST 
uses this advisory to create the CVE web site report. This web site will be 
active sometime after publication of this advisory.

c. CVSS Calculator, 
https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S..., 
web site last accessed September 6, 2016.

d. CWE-400: Uncontrolled Resource Consumption ('Resource Exhaustion'), 
http://cwe.mitre.org/data/definitions/400.html, web site last accessed 
September 6, 2016.

e. NVD, http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2016-7113, NIST 
uses this advisory to create the CVE web site report. This web site will be 
active sometime after publication of this advisory.

f. CVSS Calculator, 
https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S..., 
web site last accessed September 6, 2016.

g. CWE-592: Authentication Bypass Issues, 
http://cwe.mitre.org/data/definitions/592.html, web site last accessed 
September 6, 2016.

h. NVD, http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2016-7114, NIST 
uses this advisory to create the CVE web site report. This web site will be 
active sometime after publication of this advisory.

i. CVSS Calculator, 
https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S..., 
web site last accessed September 6, 2016.

Contact Information

For any questions related to this report, please contact ICS-CERT at:

Email: ics-cert@hq.dhs.gov (link sends e-mail)

Toll Free: 1-877-776-7585

International Callers: (208) 526-0900

For industrial control systems security information and incident reporting: 
http://ics-cert.us-cert.gov

ICS-CERT continuously strives to improve its products and services. You can 
help by choosing one of the links below to provide feedback about this 
product.

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