Re: Bypassing WAF via HTTP Pollution

Ivan Ristic <[email protected]> Mon, 8 Oct 2012 20:55:29 +0100
Newsgroups gmane.comp.security.websecurity,gmane.comp.security.web-applications,gmane.comp.security.penetration
Message-ID <CANHgQ8G=i2FzyZoOFWnqEc8cEJVdwGxqEyqeHzRSC9OQFoW9nQ@mail.gmail.com>
On Mon, Oct 8, 2012 at 10:51 AM, Robin Wood <[email protected]> wrote:
> On 4 October 2012 10:40, Ivan Ristic <[email protected]> wrote:
>> I guess this would be a good opportunity for me to mention my research
>> on the topic:
>>
>> Protocol-level evasion of web application firewalls
>> http://blog.ivanristic.com/2012/07/protocol-level-evasion-of-web-application-firewalls.html
>
> I like the table Danux has showing what order the various
> languages/technologies parse the parameters and was wondering if
> anyone had a table like this for WAFs, that way it would be a lot
> easier to match the language and the WAF and know what ordering to use
> to bypass it.

According to my reading of the blog post, the "WAF" in question was a
simulation. In reality, I wouldn't expect that you'd be able to bypass
a WAF by providing multiple instances of the same parameter. The
expected behaviour is that all such values are inspected.

Where it gets tricky is when you are able to split the payload across
two or more parameter instances, and you're attacking an application
that will combine the values into a single string. That could be handy
for bypassing WAFs, but it depends entirely on being able to craft a
payload that will not be detected in "pieces".


> Robin
>
>
>>
>> On Wed, Oct 3, 2012 at 10:55 AM, Danux <[email protected]> wrote:
>>> By playing CSAW CTF you always learn something new (at least myself).
>>>
>>> Hope you enjoy it:
>>>
>>> http://danuxx.blogspot.com/2012/10/bypassing-waf-via-http-parameter.html
>>>
>>> --
>>> DanUx
>>>
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>>
>>
>>
>> --
>> Ivan Ristić
>>
>>
>>
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-- 
Ivan Ristić

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