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Date: Wed, 8 Sep 2010 08:52:38 +0200
From: Sebastian Krahmer <>
Cc: Jon Oberheide <>,,
Subject: Re: Re: [Security] Re:  /proc infoleaks

On Tue, Sep 07, 2010 at 05:51:31PM -0400, Brad Spengler wrote:

> Definitely some work needs to be done here at the distro level, because 
> it's pointless (as Enlightenment demonstrates) to hide /proc/kallsyms 
> when /boot/ or /lib/modules are perfectly visible on any 
> distro.
I agree that distros also have to do some homework there,
but there are things that we cant just do via init harden scripts.
Take /proc/pid/stack. Other files like my prefered friend /proc/net/netlink
gives info that allows exploitation-deluxe if you overwrite your socket destructor.

The list I have given was by no means complete (and even
didnt mean slabinfo will leak addresses, but was an example
of leaking other useful info) and I prefer an inventory
of 'problematic' /proc, /sys or whatever files if you speak
about inventory of programs using it.

> I know the impulse is to immediately copy what we're doing in 
> grsecurity, but the reason we do some of the things in the way we do 
Its always my first thought :)

> them is that we can be used on any distro and have no control over 
> whatever distro that happens to be.  We also support other features like 
> PaX's KERNEXEC and UDEREF which make the symbol/address removal more 
> useful.  We're also able to make certain important assumptions about our 
> users (eg. that they want security).  So make sure you're thinking 
> carefully about what you're trying to accomplish, why you're doing it, 
> and how effective it will actually be given the (lack of) synergistic 
> features at your present disposal, instead of jumping into cargo cult 
> security.
Sure. It was just a proposal since I felt nobody really cared about
the low hanging fruits. It wont make your system rocket proof but
it makes some head-scratching for exploit developers which is
all you need if you make them stuck in doing that.


~ perl
~ $_='print"\$_=\47$_\47;eval"';eval
~ - SuSE Security Team
~ SUSE LINUX Products GmbH, GF: Markus Rex, HRB 16746 (AG Nuernberg)

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