RE: Controlling access to pdf/doc files

["Zuech, Richard" <RichardZuech () miamibeachfl gov>]

Another option might be storing those .doc and .pdf files in a Database
rather than directly on the filesystem.  The files could be stored in a
BLOB data column, and only authenticated users could access them during
their session.

Hope that helps,

Rich

-----Original Message-----
From: Sangita Pakala [mailto:sangita.pakala () paladion net] 
Sent: Tuesday, February 24, 2004 10:22 AM
To: webappsec () securityfocus com
Subject: Controlling access to pdf/doc files

Hi,

Could I have the list's thoughts on an answer we are preparing for the
next version of the AppSec FAQ at OWASP.
 
Question - How can I ensure my application allows only authenticated
users access to files like *.pdf or *.doc?

Issue - Suppose a web site, say a bank site, displays the user's account
statement as a .doc file. What if someone tries to access this file by
typing its full URL into the address bar? How does the application check
whether the user trying to access the file is the authenticated user and
that the session has not expired? 

Solution - One solution is to have a random number for the name of the
file or the folder containing it. This random number could even be
related to the session token of the user. This file/folder should then
be deleted as soon as the user's session has expired.

Are there better methods available to address this issue? Can the web
server run a server side program to verify the session token before
serving the final GET request for the file? 


Thanks,
Sangita.

OWASP AppSec FAQ
http://www.owasp.org/documentation/appsecfaq

Paladion Networks
http://www.paladion.net