On Sun, Sep 08, 2002 at 12:47:47AM -0400, Dan Merillat wrote:
> 
> > Or just replace < and > with one of these set of similar looking characters
> > (I think the last 2 are non-Unicode characters which can be shown in most
> > browsers without prompting to download silly extra packs) ????????
> 
> Like &lt; and &gt;, perhaps?
> 
> It dosn't matter, though.  IE is going to second-guess the filetype and 
> interpret
> HTML no-matter what.
> 
> The only way for them to be safe is to allow image/{gif/jpeg/png/bmp} (AND NO 
> OTHERS)
> text/html and text/plain (which we should probably promote to HTML then
> htmlentityize it.
> 
> Here's the anonymity risks:
> 
> 1) Image/somethingwedontrecognize <-- IE, netscape like to load "plugins" for
> things it dosn't recognize.   Someone could compromise the download server for
> something obscure (AOL .art format, for instance) then check referer documents
> for freenet URLs.  Not sure how possible this is as I don't know what all the
> browsers send.
> 
> 2) {video,audio}/*: As mentioned before, some formats allow redirecting to 
> URLs at the end.  Also, codec registry.  Even "safe" types like .wav are
> overridden as soon as IE sees the first few bytes of a .wma file, and dumps
> it into media player.
> 
> Safest bet: squash into application/octet stream (force download)
> 
> 3) CSS:  There's only a few ways to specify a URI in standard CSS, so we 
> should be
> able to filter that type safely.
We do. Oh, and the rest of your mail says essentially what I said in the
email titled "sarcasm".
> 
> 4) text/plain <-- mangle as described above.  Too many risks, and the 
> end-user experience
> will be the same.  (Wrap in <pre></pre> for good measure)
> 
> 5) text/html: We do a good job on this, with a few small loopholes.
> 
> "But it shouldn't be in freenet!"  I agree, 110%.  Fproxy should spin into 
> it's own side
> project, hooked into freenet ONLY via the FCP port.   This convieniently 
> means that any
> "internal" hooks (Build #, etc) would have to be exposed to other toolwriters.
> 
> --Dan
> 
> 
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> 

-- 
Matthew Toseland
mtoseland at blueyonder.co.uk
amphibian at sourceforge.net
Freenet/Coldstore open source hacker.
Looking for $coding (I'm cheap)
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