[waraxe-2005-SA#039] - Critical Sql Injection in Sgallery module for PhpNuke

[Janek Vind <come2waraxe () yahoo com>]

{================================================================================}
{                              [waraxe-2005-SA#039]   
                          }
{================================================================================}
{                                                     
                          }
{             [ Critical Sql Injection in Sgallery
module for PhpNuke ]          }
{                                                     
                          }
{================================================================================}
                                                      
                                                      
                  
Author: Janek Vind "waraxe"
Date: 12. January 2005
Location: Estonia, Tartu
Web: http://www.waraxe.us/advisory-39.html


Affected software description:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Module's Name: SGallery
Module's Version: 1.01
Module's Description: Simple JPG image gallery
License: GNU/GPL
Author's Name: Sergey Kiselev
Author's Email: ser () acmetelecom ru

Homepage: http://www.ser.acmetelecom.ru


Vulnerabilities:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Let's look at source code from imageview.php:


----------------[ original code ]---------------

require_once("$DOCUMENT_ROOT/config.php");
require_once("$DOCUMENT_ROOT/includes/sql_layer.php");
  
  $dbi = sql_connect
($dbhost,$dbuname,$dbpass,$dbname);

  if ($idalbum) {
    $result = sql_query("select picture from
".$prefix."_SGalbums where idalbum=".$idalbum,$dbi);
  } elseif ($idimage) {
    $result = sql_query("select picture from
".$prefix."_SGimages where idimage=".$idimage,$dbi);
  }

  list($echo) = sql_fetch_row($result, $dbi);
  sql_free_result($result);

  sql_logout ($dbi);

  header ("Content-Type: image/jpeg");
  echo $echo;

----------------[ /original code ]---------------

Now let's analyze the weak points.


A - Full Path Disclosure
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

If "$idalbum" and "$idimage" are both unset, then
because of the open "if/elseif" construction
there variable "$result" will be unset or can be
poisoned through GET/POST/COOKIE.
And next call of the "sql_fetch_row()" will trigger
generic php error messages, leading to
full path disclosure. Path disclosure is considered as
low level security threat, but anyway it's
useful for further malicious actions.


B - Potential arbitrary file inclusion:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This kind of code construction as

require_once("$DOCUMENT_ROOT/config.php");
require_once("$DOCUMENT_ROOT/includes/sql_layer.php");

is not very secure. Depending of the webserver
software vendor,version number and configuration
settings it can lead to arbitrary file inclusion and
possible remote file inclusion.


C - Critical sql injection bug in "imageview.php":
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Looking at source code, presented above, we can see
unsecure sql queries directed to the database.
To be excact, user submitted variables "$idalbum"
and/or "$idimage" are used in sql "SELECT" clause
without escaping with single quotes. This is clearly
sql injection bug. Further exploitation will
depend on database software and version. In case of
the mysql version 4.x with UNION functionality
enabled,
arbitrary data can be retrieved from database,
inluding admin(s) authentication credentials.
Traditionally, there is the proof of concept:


----------------[ real life exploit ]---------------

http://localhost/nuke75/modules/Sgallery/imageview.php?idimage=-99/**/UNION/
**/SELECT/**/pwd/**/FROM/**/nuke_authors/**/WHERE/**/radminsuper=1

----------------[/real life exploit ]---------------

Best browser to test this POC is MSIE - it will show
plaintext admin password's md5 hash as needed.
Firefox and other browsers will mostly rendering out
"broken picture" because of the
"Content-Type: image/jpeg" header. But anyway, sql
injection exists, can be exploited and must be
fixed by vendor as soon as possible.


How to fix:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Developer first contacted: 16. November 2004
No response from developer after multiple sent emails.
Downloadable version of the Sgalley is still
unpatched.

How to fix this security hole -
http://www.waraxe.us/forums.html


Additional resources:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Base64 encoder and decoder -
http://base64-encoder-online.waraxe.us/
SiteMapper - free php script for phpNuke powered
websites - http://sitemapper.waraxe.us/
It's easy to install solution for making phpNuke more
Google friendly!


Greetings:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Greets to icenix, Raido Kerna, g0df4th3r and
slimjim100!
Tervitused - Heintz!

Contact:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    come2waraxe () yahoo com
    Janek Vind "waraxe"

    Homepage: http://www.waraxe.us/

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