Re: IWAM: Writing temp files to \winnt\temp

[Tyler Durden <fadingreality414 () yahoo com>]

Theres one crazy idea I have about that. Now remember,
this is a long shot. Since some program somewhere has
to delete whats in temp, if the account with write
permission to the directory crafted a filename (or
just file possibly) so long that it was just
disgusting, it might be able to cause the program to
hang. That could be a DOS in itself. Besides that, it
could fill up disk space. Lets say the site allows
users to register. Their information has to be stored
SOMEWHERE. Now if theres no more disk space, how might
the registration information be saved?

This was all abstract, and just a what-if.

--Oedipus

--- Joey Peloquin <joeyp () voteprivacy com> wrote:

> Greetings,
> I'm a security analyst with a large retail company.
>
> Our web application developers are writing a web
> service, which is called by 
> COM.  It is written in dotnet, and they are
> impersonating IWAM.
>
> Since IWAM is making the call, temporary files are
> written to \winnt\temp, 
> the value of the system %temp% and %tmp% variables. 
> I've complained that I 
> don't like the idea of granting write to an
> anonymous account on 
> \winnt\temp, but have been unable to locate any
> specific information on the 
> risk of doing so.
>
> Since the ASPNET account already has write to the
> directory (this is 
> apparently done when the framework is installed?),
> and I cannot find any 
> instances of other security practitioners having a
> problem with it, I am 
> losing this fight.  To compound matters, all of the
> references I've found to 
> \winnt\temp and serialization have lead to posts
> decreeing the resolution of 
> permission woes by granting 'write' on \winnt\temp
> for IWAM.
>
>  From a pen-test perspective, what is the actual
> level of risk is associated 
> with the developer's request?  Do you know of any
> papers or other 
> information that accurately discusses the risk, if
> any, of allowing IWAM to 
> write to \winnt\temp?
>
> Changing the value of the system %temp% and %tmp%
> variables is not possible.
>
> Thanks for any insight.
>
> Joey



                
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