[imp] BUG: php 5 suhosin triggers MBOX_PREFIX separator

[Olivier]

Yes, but is this the only edge effect of suhosin ?
Olivier

Le 23/05/2011 21:04, azurIt a écrit :
> this can be disabled in suhosin:
> http://www.hardened-php.net/suhosin/configuration.html#suhosin.post.disallow_nul 
>
>
>
>
> ______________________________________________________________
> > Od: "Michael M Slusarz" > Komu: imp at lists.horde.org
> > Dátum: 23.05.2011 21:00
> > Predmet: Re: [imp] BUG: php 5 suhosin triggers MBOX_PREFIX separator
> >
> Quoting Rick Romero :
> > Quoting Michael M Slusarz : > >> Quoting Rick Romero : >> >>> 
> Quoting Michael M Slusarz : >>> >>>> Quoting Olivier : >>>> >>>>>> 
> suhosin[2446]: ALERT - ASCII-NUL chars not allowed within >>>>>> 
> request variables - dropped variable 'view' (attacker >>>>>> 
> 'XXX.XXX.XXX.XXX', file '.../services/ajax.php') >>>> >>>> Still 
> waiting for someone to tell me how a NULL character, by >>>> itself, 
> is a security threat. >>> >>> What if the variable is expected to be 
> numeric and you start doing >>> math on it? >> >> But what if the 
> variable ends up being 0.  That's a perfectly valid >> integer, but 
> could cause problems if the application uses it as a >> divisor. >> 
> >>> Isn't the purpose of suhosin to try and catch the stuff developers 
> >>> didn't catch? >> >> But you can't break things that are supposed 
> to work otherwise. >> NULL is a perfectly acceptable input in URL 
> parameters. >> >> And, e.g. with the 0 value above, the interpreter 
> CAN'T possibly >> catch/process all valid inputs.  That is the duty of 
> the >> application author. > > I dunno.  I agree with your last 
> paragraph, it's not suhosin's job > to be a substitute for proper 
> input validation.   But kinda I think > that contradicts 'NULL is a 
> perfectly acceptable input..'. > I mean - Do you really design an 
> application and say "Yep, we're > going to expect a user (or unknown 
> entity) to send a NULL here" ?
> Why not?  That may be YOUR belief, or the way that you would code   
> things, but the fact is *BOTH* PHP and the URL specs allow this to   
> happen.  So it is broken behavior to disallow this.  Period.
> In our case, we need a way to indicate a mailbox is not an IMAP   
> mailbox.  I chose the method of including a null character in the   
> mailbox string since this is the ONLY character not allowed in IMAP   
> mailboxes (yes, all other control characters are allowed).  It works   
> great everywhere - as it should because it doesn't violate any spec or 
>   API - except when using suhosin.  Suhosin = broken.
> > Assuming it's coded 'properly' that variable should have been > 
> pre-set in code, and upon receiving a URL param with data outside > 
> the expected range (numerical, >0), promptly ignored it.  Or am I > 
> wrong?
> You would be wrong.  Why do you want to ignore proper URL form data?   
> If someone sends you an encoded null character (%00), that's a   
> character within the allowed range so why should it be treated any   
> differently?
> What if I have a page that sends the first 16 bytes of an image   
> provided to it to the server to do some kind of MIME Magic testing -   
> preventing the need to send the whole file.  This binary data may   
> contain nulls.  Who are you to tell me that this is a "security"   
> violation?
> Just because null characters can be used for things such as buffer   
> overruns in certain languages does not mean they are evil.  You simply 
>   can't remove them from a data stream without knowing the context.  I 
>   would be very wary of running something that supposedly "increases" 
>   security on your machine when the actual theory behind that code is 
>   this deeply flawed.
> michael
> ___________________________________ Michael Slusarz [slusarz at horde.org]