Sielco PolyEco Digital FM Transmitter 2.0.6 Authorization Bypass

Sielco PolyEco Digital FM Transmitter 2.0.6 Authorization Bypass Factory ResetVendor: Sielco S.r.lProduct web page: https://www.sielco.orgAffected 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:10.19Summary: PolyEco is the innovative family of high-end digitalFM transmitters of Sielco. They are especially suited as highperformance power system exciters or compact low-mid powertransmitters. The same cabinet may in fact be fitted with 50,100, 300, 500, 1000W power stage (PolyEco50, 100, 300, 500,1000).All features can be controlled via the large touch-screen display4.3" or remotely. Many advanced features are inside by defaultin the basic version such as: stereo and RDS encoder, audiochange-over, remote-control via LAN and SNMP, "FFT" spectralanalysis of the audio sources, SFN synchronization and much more.Desc: Improper access control occurs when the application providesdirect access to objects based on user-supplied input. As a resultof this vulnerability attackers can bypass authorization and accessresources behind protected pages.Tested on: lwIP/2.1.1 (http://savannah.nongnu.org/projects/lwip)Vulnerability discovered by Gjoko 'LiquidWorm' KrsticMacedonian Information Security Research and Development LaboratoryZero Science Lab - https://www.zeroscience.mk - @zeroscienceAdvisory ID: ZSL-2023-5768Advisory URL: https://www.zeroscience.mk/en/vulnerabilities/ZSL-2023-5768.php26.01.2023--index.htm:----------54: function dologin() {55:             var hash = hex_md5($('#password').val() + id);56:             $.get('/login.cgi', {57:                 user: $('#user').val(),58:                 password: hash,59:                 id: id60:             }).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:                     else71:                         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 theXML 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 redirectsthe user to '/index.htm', otherwise, it writes a cookie called 'polyeco' with thevalue of 'id' and expires after 180 days.After that it checks the value of the 'user' variable, if it's greater than or equalto 3, it redirects the user to '/protect/factory.htm', otherwise it redirects theuser to '/protect/index.htm'. An attacker can exploit this by modifying the client-sideJavaScript to always set the 'user' variable to a high value (4), or by tampering withthe 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.