RE: blocking CSRF attacks

["Boaz Shunami" <BoazS () comsecglobal com>]

Hi,

Referrer can be spoofed; same goes for post and get requests, hence this
method will not be reliable as a security mechanism.
                             
Boaz Shunami

-----Original Message-----
From: listbounce () securityfocus com [mailto:listbounce () securityfocus com]
On Behalf Of Paul Johnston
Sent: Friday, December 14, 2007 8:57 PM
To: Pawan; webappsec () securityfocus com
Subject: Re: blocking CSRF attacks

Hi,

> any one on the list aware of any IDS/IPS capable of blocking CSRF
> attacks? 
> If not, what will be the best policy to block CSRF.
>  
The best fix is to code you application to include a random token on all

forms that cause an action, and validate this when the form is
submitted.

Now, I guess you're after a quick fix? One possibility is to block POST 
requests that have a referer, and the referer is not from your domain. 
I've not tried this, but I expect it would block most attacks without 
interfering with legitimate traffic.

This does assume your pages that cause actions only respond to POST 
requests, which may not be true in practice.

Paul

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Sponsored by: Watchfire
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With the rapid rise in the number and types of security threats, web application security assessments should be 
considered a crucial phase in the development of any web application. What methodology should be followed? What tools 
can accelerate the assessment process? Download this Whitepaper today!

https://www.watchfire.com/securearea/whitepapers.aspx?id=70170000000940F
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