Sielco PolyEco Digital FM Transmitter 2.0.6 Authorization Bypass Factory Reset  
Vendor: Sielco S.r.l  
Product web page:  
Affected version: PolyEco1000 CPU:2.0.6 FPGA:10.19  
PolyEco1000 CPU:1.9.4 FPGA:10.19  
PolyEco1000 CPU:1.9.3 FPGA:10.19  
PolyEco500 CPU:1.7.0 FPGA:10.16  
PolyEco300 CPU:2.0.2 FPGA:10.19  
PolyEco300 CPU:2.0.0 FPGA:10.19  
Summary: PolyEco is the innovative family of high-end digital  
FM transmitters of Sielco. They are especially suited as high  
performance power system exciters or compact low-mid power  
transmitters. The same cabinet may in fact be fitted with 50,  
100, 300, 500, 1000W power stage (PolyEco50, 100, 300, 500,  
All features can be controlled via the large touch-screen display  
4.3" or remotely. Many advanced features are inside by default  
in the basic version such as: stereo and RDS encoder, audio  
change-over, remote-control via LAN and SNMP, "FFT" spectral  
analysis of the audio sources, SFN synchronization and much more.  
Desc: Improper access control occurs when the application provides  
direct access to objects based on user-supplied input. As a result  
of this vulnerability attackers can bypass authorization and access  
resources behind protected pages.  
Tested on: lwIP/2.1.1 (  
Vulnerability discovered by Gjoko 'LiquidWorm' Krstic  
Macedonian Information Security Research and Development Laboratory  
Zero Science Lab - - @zeroscience  
Advisory ID: ZSL-2023-5768  
Advisory URL:  
54: function dologin() {  
55: var hash = hex_md5($('#password').val() + id);  
56: $.get('/login.cgi', {  
57: user: $('#user').val(),  
58: password: hash,  
59: id: id  
60: }).done(function (data) {  
61: var dati = $.parseXML(data);  
62: id = $(dati).find('id').text();  
63: user = $(dati).find('u').text();  
64: if (id == 0)  
65: window.location.href = '/index.htm';  
66: else {  
67: scriviCookie('polyeco', id, 180);  
68: if (user >= 3)  
69: window.location.href = '/protect/factory.htm';  
70: else  
71: window.location.href = '/protect/index.htm';  
72: }  
73: });  
74: }  
The function 'dologin()' in index.htm is called when a user submits a login form.  
It starts by calculating a hash of the user-entered password and a variable 'id'  
using the hex_md5 function. Then it makes an HTTP GET request to the 'login.cgi'  
endpoint with the user's entered username, the calculated password hash and the  
'id' variable as parameters. If the request is successful, the function parses the  
XML data returned from the server, extracting the values of the 'id' and 'u' elements.  
Then it checks the value of the 'id' variable, if it's equal to 0 then it redirects  
the user to '/index.htm', otherwise, it writes a cookie called 'polyeco' with the  
value of 'id' and expires after 180 days.  
After that it checks the value of the 'user' variable, if it's greater than or equal  
to 3, it redirects the user to '/protect/factory.htm', otherwise it redirects the  
user to '/protect/index.htm'. An attacker can exploit this by modifying the client-side  
JavaScript to always set the 'user' variable to a high value (4), or by tampering with  
the data sent to the server during the login process to change the value of the 'user'  
variable. It also works if the server's response variable 'user' is modified.