Re: [WEB SECURITY] How to Create Secure Web Applications with Struts

[Pilon Mntry <pilonmntry () yahoo com>]

Hi Dinis,

> if the presentation is on the client side (ala 
> AJAX ...

Well, when I wrote "presentation layer" I meant the
one at the server side (since the issue was Struts),
but of course, you are right that when AJAX or alike
is employed then there remains one (secure)
validation.

> For example, I did an audit to a struts based Java
> App which had massive Authorization problems ...

And I'm doing one right now :). When a developer uses
Struts Validator on a parameter with positive
approach(let's say [a-zA-Z0-9]), then it would be hard
to convince him to do another validation in his
business logic for SQL injection.

-pilon


--- Dinis Cruz <dinis () ddplus net> wrote:

> Pilon, when you say:
>
>  > However, with this approach when positive
> validation (whitelist) is used, there probably will
> be
> > unnecessary double validation: one in presentation
> layer and the other in business layer. But I guess,
> > that's one should pay for extensibility and
> security sake. 
>
> if the presentation is on the client side (ala
> AJAX), then there is only one security validation
> (since the one done at client slide has no security
> relevance and doesn't count :)
>
> Also note that doing data validation very away from
> the business logic (i.e. the presentation layer) can
> introduce massive exploitable blind spots
>
> For example, I did an audit to a struts based Java
> App which had massive Authorization problems (and
> some data validation issues too)
>
> Dinis Cruz
> Owasp .Net Project
> www.owasp.net
>
> ----------------------------------------
> From: Pilon Mntry <pilonmntry () yahoo com>
> Sent: 21 March 2006 07:36
> To: Stephen de Vries <stephen () corsaire com>
> Subject: Re: [WEB SECURITY] How to Create Secure Web
> Applications with Struts 
>
> > It may not be a big issue, but I think it's
> > important to understand 
> > how choosing the web tier as a security provider
> > could impact the 
> > extensibility of the app down the line.
>
> Nice comment. In owasp guide it goes like this;
>
> "...the web / presentation tier should validate for
> web related issues, persistence layers should
> validate
> for persistence issues such as SQL / HQL injection,
> directory lookups should check for LDAP injection,
> and
> so on."
>
> However, with this approach when positive validation
> (whitelist) is used, there probably will be
> unnecessary double validation: one in presentation
> layer and the other in business layer. But I guess,
> that's one should pay for extensibility and security
> sake. 
>
> And this is for data validation only. Authorization
> is
> another issue...
>
> And nice article by the way.
>
> -pilon
>
> --- Stephen de Vries  wrote:
>
> > Great article!
> >
> > It did make me think of a particular architectural
> > issue which seems 
> > to be cropping up more and more; that is, the
> impact
> > that 
> > implementing security in the web tier has on the
> > future extensibility 
> > of the app.
> >
> > For applications that were designed as web apps
> and
> > will continue to 
> > only be web apps for the rest of their lives, this
> > shouldn't impact 
> > much on the extensibility of the apps. If the
> > validation rules or 
> > access control requirements change, these can
> easily
> > be changed in 
> > the web tier (and as you've shown Struts makes it
> > really easy, 
> > because it's all declarative).
> > But if the application needs to be extensible,
> e.g.
> > must have a fat 
> > client down the road or must expose web services,
> > then any security 
> > implemented in the web tier would have to be
> > re-implemented in all 
> > the other facades. To be truly extensible
> > applications should 
> > implement security functionality in the business
> > tier so that any 
> > changes to the presentation technology (or new
> > technologies) don't 
> > impact the core functionality. E.g. for classic
> > J2EE technologies 
> > this would mean implementing access control on the
> > EJB's themselves 
> > rather than in the web tier. This is also the
> > approach taken by the 
> > Spring framework: both access control and input
> > validation are tied 
> > to the beans that form the middle tier, not the
> > presentation.
> >
> > It may not be a big issue, but I think it's
> > important to understand 
> > how choosing the web tier as a security provider
> > could impact the 
> > extensibility of the app down the line.
> >
> > 2p
> >
> > Stephen
> >
> >
> > On 20 Mar 2006, at 02:44, bugtraq () cgisecurity net
> > wrote:
> >
> > > "This article will focus on developing secure
> Web
> > applications with 
> > > the popular Java framework Struts.
> > > It will detail a set of best practices using the
> > included security 
> > > mechanisms. The first section will
> > > provide an overview of both Struts and Web
> > application security as 
> > > a context for discussion. Each
> > > subsequent section will focus on a specific
> > security principle and 
> > > discuss how Struts can be leveraged
> > > to address it."
> > >
> > > http://be.sys-con.com/read/192434.htm
> > >
> > > - zeno
> > > http://www.cgisecurity.com/ Application Security
> > News, and more!
> > > http://www.cgisecurity.com/index.rss [RSS Feed]
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> > > The Web Security Mailing List
> > > http://www.webappsec.org/lists/websecurity/
> > >
> > > The Web Security Mailing List Archives
> http://www.webappsec.org/lists/websecurity/archive/
> > >
> >
> > -- 
> > Stephen de Vries
> > Corsaire Ltd
> > E-mail: stephen () corsaire com
> > Tel: +44 1483 226014
> > Fax: +44 1483 226068
> > Web: http://www.corsaire.com
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