Moxa PT-7728 Series Switch Improper Authorization Vulnerability

OVERVIEW

Researcher Can Demirel of Biznet Bilisim has identified an improper authorization vulnerability in Moxa’s 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 AUTHORIZATIONCWE-285: Improper Authorization, http://cwe.mitre.org/data/definitions/285.html, web site last accessed June 16, 2016.

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-2016-4514NVD, 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. 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).CVSS Calculator, https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:L, web site last accessed June 16, 2016.

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 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.