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www.waraxe.us Forum Index -> Remote file inclusion -> Hack this script - challenge
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Hack this script - challenge
PostPosted: Tue Jan 19, 2010 11:25 am Reply with quote
gibbocool
Advanced user
Advanced user
 
Joined: Jan 22, 2008
Posts: 208




Hey all, this is a file upload script I had on my site previously, it has been hacked somehow and I can't figure out how! So here's a challenge - someone was able to upload php files.

Code:

<?php

$host_name = "http://upload.gibbocool.com/files/";
$target = "upload/files/";
echo "Files uploaded will be <a href=http://upload.gibbocool.com/files>viewable to the public</a>.<br><br>";

$filename = basename( $_FILES['uploaded']['name']) ;
$file_append = rand(1000,1000000);
$file_basename = substr($filename, 0, strripos($filename, '.')); // strip extention
$file_ext      = substr($filename, strripos($filename, '.'));
$filename = $file_basename . $file_append . $file_ext;
$target = $target . $filename;

$ok=1;


$uploaded_type = $_FILES['uploaded']['type'];
$uploaded_size = $_FILES['uploaded']['size'];

//This is our size condition
if ($uploaded_size > 262144000)
{
echo "Your file is too large.<br>";
$ok=0;
}

if ($uploaded_type != "image/jpeg" && $uploaded_type != "image/png" && $uploaded_type != "image/jpeg" && $uploaded_type != "text/plain" && $uploaded_type != "image/pjpeg" && $uploaded_type != "image/gif" && $uploaded_type != "application/zip" && $uploaded_type != "application/gzip" && $uploaded_type != "application/rar" && $uploaded_type != "application/x-msdos-program")
{
  if($uploaded_size != "") {
    echo "Bad filetype<br>";
    $ok=0;
  }
}

//Save upload attempts
if($filename != "") {
  $ref=$_SERVER['HTTP_REFERER'];
  $agent=$_SERVER['HTTP_USER_AGENT'];
  $ip=$_SERVER['REMOTE_ADDR'];
  $time=date('Y-m-d-G:i:s');
 
  $file = fopen("attempts.txt", "a");
  $fstring = "File: $filename Type: $uploaded_type Size: $uploaded_size IP: $ip REF: $ref Agent: $agent Time: $time";
  fwrite($file, $fstring);
  fwrite($file,"\n");
  fclose($file);
}

//Here we check that $ok was not set to 0 by an error
if ($ok==0)
{
echo "Sorry your file was not uploaded";
}

//If everything is ok we try to upload it
else
{
if(move_uploaded_file($_FILES['uploaded']['tmp_name'], $target))
{

echo "
     Upload Successful!

     <center>
     <table border=0>
        <tr>
            <td>
                <input type=\"text\" onclick=\"highlight(this)\" size=70 value=\"".$host_name.$filename."\"><br><br>
            </td>
            <td valign=\"right\">
        <a href='".$host_name.$filename."'>Direct Link</a>
            </td>
        </tr>

        <tr>
            <td>
                <input type=\"text\" onclick=\"highlight(this)\" size=70 value=\"[url=http://gibbocool.com][img]".$host_name.$filename."[/img][/url]\"><br><br>
            </td>
            <td valign=\"right\">
        Hotlink for Forums
            </td>
        </tr>

        <tr>
            <td>
                <input type=\"text\" onclick=\"highlight(this)\" size=70 value=\"&lt;a href=&quot;http://gibbocool.com&quot;&gt;&lt;img src=&quot;".$host_name.$filename."&quot; border=&quot;0&quot; alt=&quot;Image Hosted by Gibbocool.com&quot;/&gt;&lt;/a&gt;\"><br><br>
            </td>
            <td valign=\"right\">
        Hotlink for Websites
            </td>
        </tr>
    </table>
       </center>
";
}
else
{
echo "Select a file to upload.";
}
}


?>

_________________
http://www.gibbocool.com
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PostPosted: Tue Jan 19, 2010 2:47 pm Reply with quote
waraxe
Site admin
Site admin
 
Joined: May 11, 2004
Posts: 2407
Location: Estonia, Tartu




This script is affected by old Apache feature. It appears, that Apache will try to parse files with ".php" in filename as php files, if MIME is unknown to webserver.
Some years ago RAR files were usable, now Apache recognizes them.
Still, pjpeg is unknown to Apache, so:

1. write php script and name it as "1.php.2.pjpeg"
2. upload to the server
3. access via http:

http://localhost/test/1.php.2669917.pjpeg

Wink

Some real world examples:


http://securityreason.com/wlb_show/WLB-2010010050
http://www.waraxe.us/advisory-57.html
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PostPosted: Tue Jan 19, 2010 8:29 pm Reply with quote
Cyko
Moderator
Moderator
 
Joined: Jul 21, 2009
Posts: 375




Heres a quick patch (untested):

Code:
<?php

$host_name = "http://upload.gibbocool.com/files/";
$target = "upload/files/";
echo "Files uploaded will be <a href=http://upload.gibbocool.com/files>viewable to the public</a>.<br><br>";

$filename = basename($_FILES['uploaded']['name']);
$file_append = rand(1000,1000000);
$file_basename = substr($filename, 0, strripos($filename, '.')); // strip extention
//improved ext so it looks at the end
$file_ext =  strtolower(end(explode('.',$filename)));
$filename = $file_basename . $file_append . $file_ext;
$target = $target . $filename;

$ok=1;

$uploaded_type = $_FILES['uploaded']['type'];
$uploaded_size = $_FILES['uploaded']['size'];
$uploaded_type = $_FILES['uploaded']['name'];

//This is our size condition
if ($uploaded_size > 262144000)
{
echo "Your file is too large.<br>";
$ok=0;
}

//the allowed extensions - i converted the mime to the actual ext
$allowedExtensions = array('jpg','png','gif', 'txt', 'zip', 'gzip', 'rar', 'dll', 'pjpeg');


//not an allowed extension
if(!in_array($file_ext,$allowedExtensions)){
$ok=0;
}

//no size
if($uploaded_size != "") {
$ok=0;
}

//must not contain .php within filename even if extension is valid

if(preg_match("#.php#i", $uploaded_type)) {
$ok=0;
}

//Save upload attempts
if($filename != "") {
  $ref=$_SERVER['HTTP_REFERER'];
  $agent=$_SERVER['HTTP_USER_AGENT'];
  $ip=$_SERVER['REMOTE_ADDR'];
  $time=date('Y-m-d-G:i:s');
 
  $file = fopen("attempts.txt", "a");
  $fstring = "File: $filename Type: $uploaded_type Size: $uploaded_size IP: $ip REF: $ref Agent: $agent Time: $time";
  fwrite($file, $fstring);
  fwrite($file,"\n");
  fclose($file);
}

//Here we check that $ok was not set to 0 by an error
if ($ok==0)
{
echo "Sorry your file was not uploaded";
}

//If everything is ok we try to upload it
else
{
if(move_uploaded_file($_FILES['uploaded']['tmp_name'], $target))
{

echo "
     Upload Successful!

     <center>
     <table border=0>
        <tr>
            <td>
                <input type=\"text\" onclick=\"highlight(this)\" size=70 value=\"".$host_name.$filename."\"><br><br>
            </td>
            <td valign=\"right\">
        <a href='".$host_name.$filename."'>Direct Link</a>
            </td>
        </tr>

        <tr>
            <td>
                <input type=\"text\" onclick=\"highlight(this)\" size=70 value=\"[url=http://gibbocool.com][img]".$host_name.$filename."[/img][/url]\"><br><br>
            </td>
            <td valign=\"right\">
        Hotlink for Forums
            </td>
        </tr>

        <tr>
            <td>
                <input type=\"text\" onclick=\"highlight(this)\" size=70 value=\"&lt;a href=&quot;http://gibbocool.com&quot;&gt;&lt;img src=&quot;".$host_name.$filename."&quot; border=&quot;0&quot; alt=&quot;Image Hosted by Gibbocool.com&quot;/&gt;&lt;/a&gt;\"><br><br>
            </td>
            <td valign=\"right\">
        Hotlink for Websites
            </td>
        </tr>
    </table>
       </center>
";
}
else
{
echo "Select a file to upload.";
}
}


?>


Smile


Last edited by Cyko on Tue Jan 19, 2010 10:14 pm; edited 2 times in total
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PostPosted: Tue Jan 19, 2010 9:10 pm Reply with quote
waraxe
Site admin
Site admin
 
Joined: May 11, 2004
Posts: 2407
Location: Estonia, Tartu




Your check is case sensitive:

Code:

if(preg_match("#.php#", $uploaded_type))


If we use "1.pHp.2.pjpeg", then checking will be passed,
but Apache still parses file as php script.
I have seen solutions, where all dots "." except last one are converted to underscores. This will effectively counteract such vulnerability.
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PostPosted: Tue Jan 19, 2010 9:29 pm Reply with quote
Cyko
Moderator
Moderator
 
Joined: Jul 21, 2009
Posts: 375




waraxe wrote:
Your check is case sensitive:

Code:

if(preg_match("#.php#", $uploaded_type))


If we use "1.pHp.2.pjpeg", then checking will be passed,
but Apache still parses file as php script.
I have seen solutions, where all dots "." except last one are converted to underscores. This will effectively counteract such vulnerability.


Fixed, updated the code.
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PostPosted: Wed Jan 20, 2010 6:36 am Reply with quote
gibbocool
Advanced user
Advanced user
 
Joined: Jan 22, 2008
Posts: 208




nice work, I'm sure people who want a secure upload script will find this useful

_________________
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Hack this script - challenge
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