FreeBSD and User Security

[cpghost]

On Wed, 11 Jun 2008 19:45:51 -0500
Jeffrey Goldberg <jeffrey at goldmark.org> wrote:

> On Jun 11, 2008, at 7:17 PM, dfeustel at mindspring.com wrote:
> 
> > A relatively new security threat known as 'The Blue Pill', based
> > upon hardware, is a class of virtual rootkits that can silently
> > take over Intel and AMD systems. A good site to visit to learn
> > about these virtual
> > rootkits is http://invisiblethings.org/index.html.
> 
> That is simple (in concept) yet absolutely brilliant!  I'm sure that  
> people much smarter that I am have thought about these things more  
> carefully than I have, but I'm not convinced that a blue pill would
> be completely undetectable.
> 
> First it should consume memory.  A very complete test of memory  
> through a modified memtest should be able to detect whether system  
> reported memory is accurate.

What if memtest already runs within the virtualization box? How can it
determine what the "right" amount of memory is supposed to be? And if
the virtualizer hot-patched memtest instructions, either on loading it
or dynamically while it runs, it  could make it report whatever it
liked.

> Secondly, a blue pill would need to be reinserted after a hard  
> reboot.  Therefore a look at the boot process (of a non-live system)  
> should be able to see whether there is something that reinserts the  
> blue pill.

Yes, but you've got to have a very close look at it, as it won't
necessarily appear on the screen -- being caught as well by the
virtualizer. And Joanna also has a paper about fooling hardware
capture cards into reporting bogus data on her site, so you won't
even be able to detect that RAM contains something else upon boot
than those hardware capture cards are supposedly reporting.

If all this is as she's described, it is truly brilliant from a
technical POV... and a very worrying thought as well.

> But even if detection is possible these ways, a Blue Pill would be  
> extremely difficult to detect once inserted, and so the focus would  
> have to be entirely on prevention.
> 
> Again, these are just my first thoughts after looking at this very  
> briefly.  The people who come up with this stuff and do proper  
> analysis are both smarter and more knowledgeable than I am.
> 
> Cheers,
> 
> -j

-cpghost.

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