Headline
ABB Cylon FLXeon 9.3.5 (bbmdList.js) Authenticated Config Poisoning
The ABB Cylon FLXeon BACnet controller suffers from a configuration poisoning vulnerability in the put() function of bbmdList.js, where the writeFile() function is invoked to persist user-controlled data (req.body.bipList and req.body.natList) directly into sensitive configuration files (/etc/bdt.txt and /etc/bdt2.txt). This write operation lacks input validation and integrity checks allowing an attacker to supply crafted JSON payloads to inject or overwrite trusted BACnet BBMD entries. As these files are critical for network configuration, exploitation may result in unauthorized network redirection, denial of service, or insertion of rogue nodes into the system, thereby undermining the integrity and security of OT network communications.
Title: ABB Cylon FLXeon 9.3.5 (bbmdList.js) Authenticated Config Poisoning
Advisory ID: ZSL-2025-5935
Type: Local/Remote
Impact: Security Bypass, Manipulation of Data, 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 suffers from a configuration poisoning vulnerability in the put() function of bbmdList.js, where the writeFile() function is invoked to persist user-controlled data (req.body.bipList and req.body.natList) directly into sensitive configuration files (/etc/bdt.txt and /etc/bdt2.txt). This write operation lacks input validation and integrity checks allowing an attacker to supply crafted JSON payloads to inject or overwrite trusted BACnet BBMD entries. As these files are critical for network configuration, exploitation may result in unauthorized network redirection, denial of service, or insertion of rogue nodes into the system, thereby undermining the integrity and security of OT network communications.
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_config1.txt
Credits
Vulnerability discovered by Gjoko Krstic - <[email protected]>
References
[1] https://packetstorm.news/files/id/193140/
Changelog
[19.05.2025] - Initial release
Contact
Zero Science Lab
Web: https://www.zeroscience.mk
e-mail: [email protected]