Multiple Security Issues Found In AZBB
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# GulfTech Security Research April 19th, 2005
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# Vendor : AZBB
# URL : http://azbb.cyaccess.com/
# Version : AZBB 1.0.07d && Earlier
# Risk : Multiple Vulnerabilities
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Description:
azbb is a forum that was written with a primary focus on
security. azbb does not require a database such as MySQL,
PostGres or MSSQL and can even be used as a blog, or portal of
sorts. Unfortunately there are a number of security issues in AZBB
versions prior to 1.0.08, but none of these issues are considered
"high risk". However, the developer has addressed these issues and
all users should upgrade to the current 1.0.08 version.
File Inclusion:
There is a file inclusion vulnerability in AZBB 1.0.07a - 1.0.07c
that is the result of missing code that is present in all of the
other AZBB versions. This file inclusion issue poses a different
risk level depending on your server configuration. Lets have a
look at the code in question. @ /azbb_center/source/main_index.php
########## Get the Abstraction Layer
$inc = $dir_src.'/'.$abs_layer.'_db_ops.php';
file_exists($inc) ? include($inc) : exit('Unable to open '.$inc);
Since the "AZBB KEY CHECK" that exists in other pages is missing
from this page we can influence both the $dir_src and $abs_layer
variables if register globals is on. However, what we can do with
this greatly depends on the server configuration, and this is a
result of the file_exists() function being used. You can read
more about this in the official php manual located here
http://us2.php.net/file_exists
Arbitrary File Deletion:
There is an issue in AZBB that could allow for an attacker logged
in as an admin, or a malicious admin to delete arbitrary files
outside the scope of the application. The vulnerable code is in
admin_avatar.php and admin_attachment.php Lets have a look at the
code in admin_avatar.php
## trim all and delete
foreach ($_POST['avat_select'] as $ent)
{
if (file_exists($dir_avatar.'/'.$ent))
{ unlink($dir_avatar.'/'.$ent); }
}
As we can see there are no checks made for traversal sequences,
and a user with admin privileges could easily delete arbitrary files
on the server. The vulnerability in admin_attachment.php is nearly
identical.
Arbitrary File Enumeration:
There is an issue in AZBB that can be exploited by both users and
guests alike to tell whether or not files on the target server exists.
This is due to a file check coming before the input is cleaned in
attachment.php
elseif (!file_exists($dir_att.'/'.$_POST['attachment'])) {$error =
$txt_err[13];}
This issue can not be used to download arbitrary files, because the
input is cleaned before the file is included, but we can enumerate
files. To check if a file exists on the target web server all an
attacker has to do is modify the "attachment" parameter to include
traversal sequences. If the file exists we will be prompted with a
download, and if it doesn't exists we will see an error message.
Solution:
The developer of AZBB was very quick to respond and has addressed
these issues. A complete change log can be seen by following the
url posted below. Also, you will find the link to the updated AZBB
1.0.08 downloads below
http://azbb.cyaccess.com/azbb.php?1091778548
http://azbb.cyaccess.com/azbb.php?1091872271
All users are advised to upgrade their azbb installations as soon
as possible. A special thanks to AZ for remedying these issues so
quickly. If everyone responded in this timely of a manner it would
make what we do a lot easier :)
Related Info:
The original advisory can be found at the following location
http://www.gulftech.org/?node=research&article_id=00068-04192005
Credits:
James Bercegay of the GulfTech Security Research Team
--
No virus found in this outgoing message.
Checked by AVG Anti-Virus.
Version: 7.0.308 / Virus Database: 266.9.17 - Release Date: 4/19/2005