Re: Registration Weakness in Linux Kernel's Binary formats

[Stephen Hemminger <shemminger@osdl.org>]

On Tue, 3 Oct 2006 17:53:30 -0400
Kyle Moffett <mrmacman_g4@mac.com> wrote:

> On Oct 03, 2006, at 17:25:07, Bráulio Oliveira wrote:
> > Just forwarding....
> 
> Well, you could have checked the list archives first to make sure the  
> idiot didn't send it here himself.  Secondly if you're going to  
> forward something like this best send it to security@kernel.org first.
> 
> Of course, it's partially the abovementioned idiot's fault for BCCing  
> a mailing list and several others:
> > To: undisclosed-recipients
> 
> > Hello,
> > The present document aims to demonstrate a design weakness found in  
> > the
> > handling of simply linked   lists   used   to   register   binary    
> > formats   handled   by Linux   kernel,   and   affects   all    
> > the   kernel families (2.0/2.2/2.4/2.6), allowing the insertion of  
> > infection modules in kernel  space that can be used by malicious  
> > users to create infection tools, for example rootkits.
> 
> Would be nice if I could get to your paper to actually read it, but  
> as it returns a 404 error I'm going to make one brief statement:
> 
> If you can load another binary format or access the "simply linked  
> lists" of the binfmt chain in any way, then you're root and therefore  
> there are easier ways to own the box than patching the kernel.
> 
> Cheers,
> Kyle Moffett

I looked at it, basically his argument which is all flowered up in pretty
pictures and security vulnerability language is:

   If root loads a buggy module then the module can be used to compromise
   the system.

Well isn't that surprising.

-- 
Stephen Hemminger <shemminger@osdl.org>