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                        EightOne Research Facility
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EORF2003-04 (security advisory)

Title: sbox has a information disclosure problems

Author: Julio "e2fsck" Cesar

Vendor: http://stein.cshl.org/WWW/software/sbox

Versions: sbox 1.04 and later

Date: 18 Sep 2003



1. Description

  sbox is a CGI wrapper that allows CGIs to be executed more safely. What
sbox does is "box" the CGI script into a secure enviroment and run it.
  EightOne Research Facility has discovered a path disclosure problem in 
sbox, which allows malicious users to know the physical path of the server 
and the username of the domain.


2. Details

  When a user makes a request to /cgi-bin directory, sbox intermediates 
this query and executes the CGI script in a restricted enviroment, but before
this execution, it makes some checking such as CGI scripts in world-writable
directories. When a query to a non-existent script in /cgi-bin is made, sbox
display an error that reveals some information that shouldn't be revealed, 
such as physical path.
  Here is an example: http://your.vulnerable.site/cgi-bin/non-existent.pl
and look what we get

-- snip --
Sbox Error
The sbox program encountered an error while processing this request. 
Please note the time of the error, anything you might have been doing at 
the time to trigger the problem, and forward the information to this 
site's Webmaster (root@your.vulnerable.site).

    Stat failed. /home/jcf/cgi-bin/a.pl: No such file or directory 

sbox version 1.04
$Id: sbox.c,v 1.9 2000/03/28 20:12:40 lstein Exp $
-- unsnip --

It revealed the username of the domain and the physical path of cgi-bin 
directory. And is possible to use the gotten username to make brute force 
attacks to guess the user's password to obtain unauthorized access.


3. Solution

  Stein Laboratory has been contacted but I haven't received any reply yet.

Thanks Despise for being this cool guy and helped us when we needed.
Sorry if there are english mistakes.

Regards,
members of EightOne.

EightOne Research Facility - http://eightone.mafiadodiva.org
Recife, PE, Brazil