ICS Advisory

Honeywell XL Web Controller Directory Traversal Vulnerability

Last Revised
Alert Code


Martin Jartelius of Outpost24 has identified a directory traversal vulnerability in Honeywell’s XL Web Controller. Honeywell has produced an update that mitigates this vulnerability.

This vulnerability could be exploited remotely.


The following XLWeb controller versions are affected:

  • XL1000C50          EXCEL WEB 52 I/O,
  • XL1000C100        EXCEL WEB 104 I/O,
  • XL1000C500        EXCEL WEB 300 I/O,
  • XL1000C1000       EXCEL WEB 600 I/O,
  • XL1000C50U        EXCEL WEB 52 I/O UUKL,
  • XL1000C100U      EXCEL WEB 104 I/O UUKL,
  • XL1000C500U      EXCEL WEB 300 I/O UUKL, and
  • XL1000C1000U    EXCEL WEB 600 I/O UUKL.


An attacker may use this vulnerability to generate a valid login for an administrative user on the Honeywell XLWeb controller giving the attacker full administrator access to the system. The XLWEB application effectively becomes an entry point into the network where it is located.

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.


Honeywell is a US-based company that maintains offices worldwide.

The affected products, XLWeb controllers, are web-based SCADA systems. According to Honeywell, XLWeb controllers are deployed across several sectors including Critical Manufacturing, Energy, Water and Wastewater Systems, and others. Honeywell estimates that these products are used primarily in Europe and the Middle East.



PATH TRAVERSALCWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal'), http://cwe.mitre.org/data/definitions/22.html, web site last accessed March 17, 2015.

By using a directory traversal vulnerability in the FTP server, it is possible to gain access to the web root directory.

CVE-2015-0984NVD, http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2015-0984, 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 v2 base score of 10.0 has been assigned; the CVSS vector string is (AV:N/AC:L/Au:N/C:C/I:C/A:C).CVSS Calculator, http://nvd.nist.gov/cvss.cfm?version=2&vector=AV:N/AC:L/Au:N/C:C/I:C/A:C, web site last accessed March 17, 2015.



This vulnerability could be exploited remotely.


No known public exploits specifically target this vulnerability.


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


The update for this vulnerability is Excel Web Linux version 2.04.01 (March, 2014) or later plus the programing tool CARE version 10.02 (March 2014) or later. Customers are encouraged to contact their local Honeywell HBS branch to have their sites updated to the latest version.

In the Centraline partner channel, Excel Web controllers also have been sold under the brand name “FALCON.” Centraline partners can directly access http://www.centraline.com and get these versions.

Linux: https://www.centraline.com/index.php?id=847&route=article/index&directory_id=140&direct_link=1

CARE: https://www.centraline.com/index.php?id=847&route=article/index&directory_id=138&direct_link=1

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 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 also provides a section for control systems security recommended practices on the ICS-CERT web page athttp://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. ICS-CERT reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures.

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/).

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  • Honeywell