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/

---------------------------------- [ EOF ] ------------------------------------

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Published on: 2005-01-12 (33564 reads)