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Message-ID: <20101107123232.GB6512@elte.hu>
Date: Sun, 7 Nov 2010 13:32:32 +0100
From: Ingo Molnar <mingo@...e.hu>
To: Willy Tarreau <w@....eu>
Cc: Marcus Meissner <meissner@...e.de>, security@...nel.org,
mort@....com, Peter Zijlstra <a.p.zijlstra@...llo.nl>,
fweisbec@...il.com, "H. Peter Anvin" <hpa@...or.com>,
linux-kernel@...r.kernel.org, jason.wessel@...driver.com,
tj@...nel.org, Andrew Morton <akpm@...ux-foundation.org>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [Security] [PATCH] kernel: make /proc/kallsyms mode 400 to
reduce ease of attacking
* Willy Tarreau <w@....eu> wrote:
> On Sun, Nov 07, 2010 at 01:12:35PM +0100, Ingo Molnar wrote:
> >
> > * Willy Tarreau <w@....eu> wrote:
> >
> > > [...]
> > >
> > > It's precisely because you're making a special case of the security bug that you
> > > want to hide bugs from user-space by cheating on version.
> >
> > You claimed this for the second time and i'm denying it for the second time.
> >
> > The goal of fuzzing the version inforation is _not_ to 'hide bugs from user-space by
> > cheating on version'. The goal is to introduce uncertainty to attackers, so that a
> > honeypot silent alarm can warn the admin.
>
> My interpretation of this mechanism is what I explained above. [...]
( Well, if it's "your interpretation" only then stop claiming that i said it. )
> [...] "Introducing uncertainty" means hiding a version so that the attacker
> doesn't precisely know which one it is and has to send a few probes to guess it.
No. The 'exploit honeypot' mechanism i outlined is really simple, and it means what
i explained already:
- attacker breaks into unprivileged user-space
- attacker runs exploit
- exploit attempt gets detected by the 'exploit honeypot' kernel code and a
(silent) warning goes to the admin (via a syslog message for example)
- attacker only sees that the attack did not succeed
This makes it _unsafe_ (for many types of attackers) to run an exploit locally.
> That's not much different than trying to fire the exploit itself. [...]
Erm, the difference is possible _detection_ via a silent alarm.
There's a huge difference between 'attempting an exploit and being caught' and 'not
even trying the exploit because based on the kernel version the attacker knows it
wont work'.
Thanks,
Ingo
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