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IT Security and Insecurity Portal |
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Hack this script - challenge |
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 Posted: Tue Jan 19, 2010 11:25 am |
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| gibbocool |
| Advanced user |
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| Joined: Jan 22, 2008 |
| Posts: 208 |
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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.$filename."[/img][/url]\"><br><br>
</td>
<td valign=\"right\">
Hotlink for Forums
</td>
</tr>
<tr>
<td>
<input type=\"text\" onclick=\"highlight(this)\" size=70 value=\"<a href="http://gibbocool.com"><img src="".$host_name.$filename."" border="0" alt="Image Hosted by Gibbocool.com"/></a>\"><br><br>
</td>
<td valign=\"right\">
Hotlink for Websites
</td>
</tr>
</table>
</center>
";
}
else
{
echo "Select a file to upload.";
}
}
?>
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| Posted: Tue Jan 19, 2010 2:47 pm |
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| waraxe |
| Site admin |
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| Joined: May 11, 2004 |
| Posts: 2407 |
| Location: Estonia, Tartu |
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| Posted: Tue Jan 19, 2010 8:29 pm |
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| Cyko |
| Moderator |
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| Joined: Jul 21, 2009 |
| Posts: 375 |
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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.$filename."[/img][/url]\"><br><br>
</td>
<td valign=\"right\">
Hotlink for Forums
</td>
</tr>
<tr>
<td>
<input type=\"text\" onclick=\"highlight(this)\" size=70 value=\"<a href="http://gibbocool.com"><img src="".$host_name.$filename."" border="0" alt="Image Hosted by Gibbocool.com"/></a>\"><br><br>
</td>
<td valign=\"right\">
Hotlink for Websites
</td>
</tr>
</table>
</center>
";
}
else
{
echo "Select a file to upload.";
}
}
?> |
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Last edited by Cyko on Tue Jan 19, 2010 10:14 pm; edited 2 times in total |
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| Posted: Tue Jan 19, 2010 9:10 pm |
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| waraxe |
| Site admin |
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| Joined: May 11, 2004 |
| Posts: 2407 |
| Location: Estonia, Tartu |
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Your check is case sensitive:
| Code: |
if(preg_match("#.php#", $uploaded_type))
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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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| Posted: Tue Jan 19, 2010 9:29 pm |
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| Cyko |
| Moderator |
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| Joined: Jul 21, 2009 |
| Posts: 375 |
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| waraxe wrote: | Your check is case sensitive:
| Code: |
if(preg_match("#.php#", $uploaded_type))
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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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| Posted: Wed Jan 20, 2010 6:36 am |
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| gibbocool |
| Advanced user |
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| Joined: Jan 22, 2008 |
| Posts: 208 |
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| nice work, I'm sure people who want a secure upload script will find this useful |
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