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ABB Cylon FLXeon 9.3.4 Insecure Backup Sensitive Data Exposure

High
Advisory ID
ZSL-2025-5924
Release Date
14 February 2025
Vendor
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
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

A vulnerability exists due to an insecure backup.tgz file that, when obtained, contains sensitive system files, including main.db, SSL/TLS certificates and keys, the system shadow file with hashed passwords, and the license key. Although authentication is required to access the backup, an attacker with access could extract these files to retrieve stored credentials, decrypt secure communications, and escalate privileges by cracking password hashes. This exposure poses a significant security risk, potentially leading to unauthorized access, data breaches, and full system compromise.

Proof of Concept
Disclosure Timeline
21.04.2024Vulnerability discovered.
22.04.2024Vendor contacted.
22.04.2024Vendor responds.
02.05.2024Working with the vendor.
20.01.2025Vendor releases version 9.3.5 to address this issue.
14.02.2025Public security advisory released.
Credits
Vulnerability discovered by Gjoko Krstic
References
Changelog
14.02.2025Initial release