Headline
ABB Cylon FLXeon 9.3.5 (capture.js) Authenticated File Disclosure/Delete
The ABB Cylon FLXeon BACnet controller is vulnerable to a path traversal flaw in its capture.js endpoint due to unsanitized user input being directly concatenated into a filesystem path. An attacker can exploit this by supplying crafted file names to access arbitrary files outside the intended var/ directory. Additionally, the use of Fs.unlinkSync() after serving the file introduces a destructive impact, allowing attackers to delete system or application files.
Title: ABB Cylon FLXeon 9.3.5 (capture.js) Authenticated File Disclosure/Delete
Advisory ID: ZSL-2025-5934
Type: Local/Remote
Impact: Exposure of System Information, DoS
Risk: (5/5)
Release Date: 19.05.2025
Summary
BACnet® Smart Building Controllers. ABB’s BACnet portfolio features a series of BACnet® IP and BACnet MS/TP field controllers for ASPECT® and INTEGRA™ building management solutions. ABB BACnet controllers are designed for intelligent control of HVAC equipment such as central plant, boilers, chillers, cooling towers, heat pump systems, air handling units (constant volume, variable air volume, and multi-zone), rooftop units, electrical systems such as lighting control, variable frequency drives and metering.
The FLXeon Controller Series uses BACnet/IP standards to deliver unprecedented connectivity and open integration for your building automation systems. It’s scalable, and modular, allowing you to control a diverse range of HVAC functions.
Description
The ABB Cylon FLXeon BACnet controller is vulnerable to a path traversal flaw in its capture.js endpoint due to unsanitized user input being directly concatenated into a filesystem path. An attacker can exploit this by supplying crafted file names to access arbitrary files outside the intended var/ directory. Additionally, the use of Fs.unlinkSync() after serving the file introduces a destructive impact, allowing attackers to delete system or application files.
Vendor
ABB Ltd. - https://www.global.abb
Affected Version
FLXeon Series (FBXi Series, FBTi Series, FBVi Series)
CBX Series (FLX Series)
CBT Series
CBV Series
Firmware: <=9.3.5
Tested On
Linux Kernel 5.4.27
Linux Kernel 4.15.13
NodeJS/8.4.0
Express
Vendor Status
[21.04.2024] Vulnerability discovered.
[22.04.2024] Vendor contacted.
[22.04.2024] Vendor responds.
[02.05.2024] Working with the vendor.
[18.05.2025] No response from the vendor.
[19.05.2025] Public security advisory released.
PoC
abb_flxeon_dir2.txt
Credits
Vulnerability discovered by Gjoko Krstic - <[email protected]>
References
[1] https://packetstorm.news/files/id/193139/
Changelog
[19.05.2025] - Initial release
Contact
Zero Science Lab
Web: https://www.zeroscience.mk
e-mail: [email protected]