Re: ASHX, ASMX or What?

[Christian Sciberras <uuf6429 () gmail com>]

You shouldn't filter against known files, but do the reverse, you should
filter against known good files.

Oh and the medium you decide to throw this data should have special checks
against execution etc...



On Fri, Jun 24, 2011 at 6:16 PM, Nahuel Grisolia <nahuel () bonsai-sec com>wrote:

> List,
>
> Imagine that you're in front of an """"insecure"""" file upload in the
> context of an IIS6,7 (no ;.jpg :P) and the regex filtering the file is
> like:
>
> [anything].asp[anything] (yeah, my.aspirator.jpg is filtered hehe)
>
> No .aspx, no .asp and no .aspx;jpg even if the server is vulnerable...
>
> So... is there any way to bypass this control? Like uploading a
> malicious Webservice (can we simply upload a Webservice file? I think
> they need to be precomplied first) or something like that?
>
> Thanks a lot!
>
> regards,
> --
> Nahuel Grisolia - C|EH
> Information Security Consultant
> Bonsai Information Security Project Leader
> http://www.bonsai-sec.com/
> (+54-11) 4777-3107
>
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