Headline
ABB Cylon FLXeon 9.3.4 Session Persistence Vulnerability
User sessions on ABB Cylon FLXeon controllers remain active for up to seven days, even after a client-side logout. Clicking “Log Out” does not properly revoke the session on the server, allowing attackers with access to stolen session tokens to maintain unauthorized access. This increases the risk of session hijacking and privilege abuse.
Title: ABB Cylon FLXeon 9.3.4 Session Persistence Vulnerability
Advisory ID: ZSL-2025-5922
Type: Local/Remote
Impact: Security Bypass
Risk: (4/5)
Release Date: 13.02.2025
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
User sessions on ABB Cylon FLXeon controllers remain active for up to seven days, even after a client-side logout. Clicking “Log Out” does not properly revoke the session on the server, allowing attackers with access to stolen session tokens to maintain unauthorized access. This increases the risk of session hijacking and privilege abuse.
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.
[13.02.2025] Public security advisory released.
PoC
abb_flxeon_sess1.txt
Credits
Vulnerability discovered by Gjoko Krstic - <[email protected]>
References
[1] https://search.abb.com/library/Download.aspx?DocumentID=9AKK108470A5684&LanguageCode=en&DocumentPartId=PDF&Action=Launch
[2] https://packetstorm.news/files/id/189233/
Changelog
[13.02.2025] - Initial release
Contact
Zero Science Lab
Web: https://www.zeroscience.mk
e-mail: [email protected]