Nothing you do at the client side can be hidden. I can write a
client that downloads the source, or watch it via a proxy, or
look at the cache, etc.... don't even bother trying. You
should consider anything client side as protection from
inadvertant mistakes by users only, and you should always have a
fall back filter in place to catch the errors before they do any
damage.
On Wed, 6 Oct 2004, Ian wrote:
| Date: Wed, 06 Oct 2004 09:52:03 +0100
| From: Ian <webappsec2@fishnet.co.uk>
| Reply-To: webappsec@securityfocus.com
| To: "[ISO-8859-1] Bénoni MARTIN" <Benoni.MARTIN@libertis.ga>,
| webappsec@securityfocus.com
| Subject: Re: Web Forms filtered with SQL constraints
|
| On 5 Oct 2004 at 13:25, Bénoni MARTIN wrote:
|
| > Hi list !
| >
| > I was wondering how to solve the 2 following problems: I have ASP (not
| > ASP.NET) formulaires people have to fill in. To avoid SQ injection attacks
| > and other tricks, I have set up some Jscript filtering on each field (i.e.
| > for instance a name can just be alphabet's characters and no figures :) ),
| > and I am planning to do the same on my Database (setting up constraints).
| >
| >
| > But I have 2 questions: - How can I hide my Jscript filtering from the
| > user ? When I want to see the source, everything is diaplayed, quite
| > normal :( ... Maybe it's not so good to tell people what I have done to
| > filter them :) I saw some sites where it is impossible to see the source,
| > impossible to "hoover the site", impossible even to print ... But I have
| > not been able to find on the net how to do this :(
| >
| > - How can I deal with possible SQL errors within an ASP page ? I mean,
if
| > a field has been filled in, bypass my Jscript filtering (no matter how),
| > and gets to the database but is then "stopped" by an SQL onstraint, how do
| > I raise this error on an ASP page without diplaying an explicit error
| > (giving the user the name of my database for instance) ?
| >
| > Cheers for any clue, I am lost on this topic :(
|
| Hi,
|
| Using classic ASP with vbscript you would add this to the top of the page:
|
| <% on error resume next %>
|
| Then after every SQL query:
|
| <%
| if err then
| Response.write "There was a database error"
| ' Log to error to file
| end if
| %>
|
| I think the equivalent in JScript is the Try, Catch, Finally:
|
| http://msdn.microsoft.com/library/default.asp?url=/library/en-
| us/script56/html/js56jslrfjscripterrorstoc.asp
|
| Hope this helps
|
| Ian
| --
|
|
|
|
|
-R
The information in this email is confidential and may be legally
privileged. It is intended solely for the addressee. Access to
this email by anyone else is unauthorized. If you are not the
intended recipient, any disclosure, copying, distribution or any
action taken or omitted to be taken in reliance on it is
expressly prohibited and may be unlawful.
