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   Re: [xml-dev] Malicious XML

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> >Any chance of some details of just what it is in the internal subset 
> >which triggers this behaviour, and how?
> 
> You can easily construct a few entities that expand to a huge result.
> Depending on how your parser returns things, this may use lots of
> memory or merely use up lots of cpu time.  There is an example at
> 
>   http://www.cogsci.ed.ac.uk/~richard/billion-laughs.xml
> 
> I don't recommend loading this file into a browser.

This is exactly the attack reported to us.
So I don't need to post it anymore.

For Expat and MSXML this is a CPU hog only.
However, you can turn it into a memory hog on these parsers
by using an external subset and PE entities/references instead
of GE references/entities (except for the last one).

Karl





 

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