[Python-Dev] XML DoS vulnerabilities and exploits in Python
donald.stufft at gmail.com
Thu Feb 21 00:45:10 CET 2013
On Wednesday, February 20, 2013 at 6:22 PM, Antoine Pitrou wrote:
> On Wed, 20 Feb 2013 18:21:22 -0500
> Donald Stufft <donald.stufft at gmail.com (mailto:donald.stufft at gmail.com)> wrote:
> > On Wednesday, February 20, 2013 at 6:08 PM, Antoine Pitrou wrote:
> > > > It's not a distributed DoS issue, it's a severe DoS vulnerabilities. A
> > > > single 1 kB XML document can kill virtually any machine, even servers
> > > > with more than hundred GB RAM.
> > > >
> > >
> > >
> > > Assuming an attacker can inject arbitrary XML. Not every XML document
> > > is loaded from the Internet.
> > >
> > Even documents not loaded from the internet can be at risk. Often times
> > security breaches are the result of a chain of actions. You can say "I'm
> > not loading this XML from the internet, so therefore I am safe" but then
> > you have another flaw (for example) where you unpack a zip file
> > without verifying there are not absolute paths and suddenly your xml file has
> > been replaces with a malicious one.
> Assuming your ZIP file is coming from the untrusted Internet, indeed.
> Again, this is the same assumption that you are grabbing some important
> data from someone you can't trust.
No software you run on your computer grabs data from someone you don't trust
and it all validates that even though you trust them they haven't been exploited?
Like I said these sort of things are often caused by chaining several unrelated
> Just because you are living in a Web-centric world doesn't mean
> everyone does. There are a lot of use cases which are not impacted by
> your security rules. Bugfix releases shouldn't break those use cases,
> which means the security features should be mostly opt-in for 2.7 and
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