Title: ABB Cylon FLXeon 9.3.4 (serialConfig.js) JSON Object Flooding DoS
Advisory ID: ZSL-2025-5915
Type: Local/Remote
Impact: DoS
Risk: (4/5)
Release Date: 08.02.2025

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 an authenticated JSON flooding attack, leading to uncontrolled resource consumption and a denial-of-service (DoS) condition. The /api/serialConfig endpoint allows an authenticated attacker to abuse an unrestricted loop to create a large number of JSON objects by sending specially crafted requests through the ports JSON array. This results in excessive memory and CPU usage, causing resource exhaustion and potential service failure.

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: <=9.3.4

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.
[20.01.2025] Vendor releases version 9.3.5 to address this issue.
[08.02.2025] Public security advisory released.

PoC

jdos.py

Credits

Vulnerability discovered by Gjoko Krstic - <gjoko@zeroscience.mk>

References

N/A

Changelog

[08.02.2025] - Initial release

Contact

Zero Science Lab

Web: https://www.zeroscience.mk
e-mail: lab@zeroscience.mk