Re: Bug#668667: CVE Request (minor) -- Two Munin graphing framework flaws

[Kurt Seifried <kseifried () redhat com>]

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On 04/27/2012 09:41 AM, Steve Schnepp wrote:
> On Wed, Apr 18, 2012 at 07:04, Kurt Seifried <kseifried () redhat com>
> wrote:
> > > In addition munin parses parts of the query string. You are
> > > allowed to modify the size of the image. By choosing a path 
> > > "....png?size_x=20000&size_y=20000&uniquestuff" you can do the 
> > > same attack while simultaneously using a large image size. The
> > > raw image would be 381M (assuming 8bits/pixel) in this case. A
> > > png version will likely be smaller, say 4M? So now you have an 
> > > amplification of 4M/request. Note that this query can get a
> > > node into swapping, because rrdtool needs to create the whole
> > > image in main memory.

Please use CVE-2012-2147 for this issue (specifying the size = lots of
ram/storage space used up during image creation).

> > Ouch.
>
> I believe I fixed the bug in r4825, since : - url with query string
> aren't stored permanently anymore. - /tmp isn't used anymore per
> default (to fix #668536)
>
> Could you confirm that ?
>
> OTOH, the issue about very big imgs that gets the cgi into
> swapping isn't the same bug to be.
>
> As Helmut noticed, there is already a size cap in rrd, so do I
> still need implement one in munin ? If yes, would you mind to file
> another bugreport (for RAM exhaustion) ?
>
> Thx !
>
> r4825: http://munin-monitoring.org/changeset/4825
>
> -- Steve Schnepp http://blog.pwkf.org/


- -- 
Kurt Seifried Red Hat Security Response Team (SRT)
PGP: 0x5E267993 A90B F995 7350 148F 66BF 7554 160D 4553 5E26 7993

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