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Advisory (ICSA-16-189-02)

Moxa Device Server Web Console Authorization Bypass Vulnerability

Original release date: July 07, 2016

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OVERVIEW

Independent researcher Maxim Rupp has identified an authorization bypass vulnerability in Moxa’s Device Server Web Console. Moxa has indicated the NPort 5232-N was discontinued in 2012 and has produced recommendations to mitigate this vulnerability.

This vulnerability could be exploited remotely.

AFFECTED PRODUCTS

The following Device Server Web Console 5232-N versions are affected:

  • Device Server Web Console 5232-N, all versions.

IMPACT

An attacker could exploit this vulnerability to gain access to change settings and data on the target device.

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 product, Device Server Web Console 5232-N, is a serial to Ethernet device. According to Moxa, Device Server Web Console devices are deployed across several sectors, including Commercial Facilities and Energy. Moxa estimates that this product is used primarily in the United States, Europe, and Asia.

VULNERABILITY CHARACTERIZATION

VULNERABILITY OVERVIEW

AUTHORIZATION BYPASSa

An attacker could identify an authenticated UserId from a parameter passed in a cookie and gain access.

CVE-2016-4503b has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N).c

VULNERABILITY DETAILS

EXPLOITABILITY

This vulnerability could be exploited remotely.

EXISTENCE OF EXPLOIT

No known public exploits specifically target this vulnerability.

DIFFICULTY

An attacker with a low skill would be able to exploit this vulnerability.

MITIGATION

Moxa recommends disabling Ports 80/TCP (HTTP) and 23/TCP (TELNET). Moxa indicates that users should ensure that Ports 161/UDP (SNMP), 4800/UDP (utility), and 4900/TCP (utility) are only accessible by trusted systems and that restricting access to Ports 4800/UDP and 4900/TCP will impact remote systems administration.

ICS-CERT recommends that users take defensive measures to minimize the risk of exploitation of this vulnerability. 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 ICS‑CERT 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.


Contact Information

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

Email: ics-cert@hq.dhs.gov
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

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