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             AUSCERT External Security Bulletin Redistribution

                               ESB-2016.1558
      Moxa PT-7728 Series Switch Improper Authorization Vulnerability
                               20 June 2016

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

Product:           Moxa Industrial Ethernet Switch PT-7728 series
Publisher:         ICS-CERT
Operating System:  Network Appliance
Impact/Access:     Unauthorised Access -- Existing Account
Resolution:        Patch/Upgrade
CVE Names:         CVE-2016-4514  

Original Bulletin: 
   http://ics-cert.us-cert.gov/advisories/ICSA-16-168-01

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Advisory (ICSA-16-168-01)

Moxa PT-7728 Series Switch Improper Authorization Vulnerability

Original release date: June 16, 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

Independent researcher Can Demirel has identified an improper authorization 
vulnerability in Moxas Industrial Ethernet Switch PT-7728 series. Moxa has 
produced an update to mitigate this vulnerability. Can Demirel has tested the
update to validate that it resolves the vulnerability.

This vulnerability could be exploited remotely.

AFFECTED PRODUCTS

The following Moxa Industrial Ethernet Switches are affected:

    PT-7728 Series Version 3.4 build 15081113

IMPACT

Successful exploitation of this vulnerability may allow an attacker to access
management functions. Attackers can update switch configuration.

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

BACKGROUND

Moxa is a Taiwan-based company that maintains offices in several countries 
around the world, including the US, UK, India, Germany, France, China, Russia,
and Brazil.

The affected products, PT-7728 series, are managed Ethernet switches designed
especially for industrial applications. According to Moxa, PT-7728 series 
switches are deployed across several sectors, including Chemical, Commercial 
Facilities, Critical Manufacturing, Emergency Services, Energy, Food and 
Agriculture, Government Facilities, Water and Wastewater Systems, and others.
Moxa estimates that these products are used globally but concentrated in the 
US, Europe, Chile, Argentina, Peru, Columbia, and Taiwan, with 50 to 60 
percent of all sales in the US.

VULNERABILITY CHARACTERIZATION

VULNERABILITY OVERVIEW

IMPROPER AUTHORIZATION [a]

The switch series support least privilege account with given credentials. The
default user account has limited access to switch functions. Using local proxy
to interrupt traffic, the switch configuration can be updated. It means least
privilege account can access and modify critical switch configuration.

CVE-2016-4514 [b] has been assigned to this vulnerability. A CVSS v3 base score 
of 7.7 has been calculated; the CVSS vector string is 
(AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:L). [c]

VULNERABILITY DETAILS

EXPLOITABILITY

This vulnerability could be exploited remotely. EXISTENCE OF EXPLOIT

No known public exploits specifically target this vulnerability.

DIFFICULTY

Crafting a working exploit for this vulnerability would be difficult. Local 
proxy must be used to interrupt traffic and update switch configuration.

MITIGATION

Moxa has produced an update to mitigate this vulnerability. The update is 
available upon request.

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-285: Improper Authorization, 
http://cwe.mitre.org/data/definitions/285.html, web site last accessed June 
16, 2016.

b. NVD, http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2016-4514, 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:H/PR:L/UI:N/S..., 
web site last accessed June 16, 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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