Re: [ANNOUNCE] Release Digsig 1.5: kernel module for run-timeauthentication of binaries

[Kyle Moffett <mrmacman_g4@mac.com>]

On Apr 25, 2006, at 15:52:45, Valdis.Kletnieks@vt.edu wrote:
> On Tue, 25 Apr 2006 21:37:48 +0200, Arjan van de Ven said:
>> On Tue, 2006-04-25 at 19:57 +0100, Nix wrote:
>>> On Tue, 25 Apr 2006, Arjan van de Ven said:
>>>> so you didn't sign perl ? or bash ?
>>>
>>> You can write an elf loader in bash?!
>>
>> I've not tried it.. but afaics bash scripts are sufficiently  
>> turing complete to pull it off ;)
>
> Well, somebody did 'shasm' (an assembler in bash), so I don't see  
> any reason you can't do an elf loader... (OK, so you *might* have  
> to write a machine emulator in bash, store the binary in an array,  
> and emulate the sucker...)

Well I know that there are ways in Perl to overwrite arbitrary memory  
(it's considered a bug of a certain XS library, although it has no  
security implications because you could do the equivalent in Perl  
anyways).  I would assume that it's quite possible to do the same in  
bash with a specially formatted bash script.  Once you can scribble  
on arbitrary memory, you can load a compiled ELF loader and execute  
it without much trouble at all.  A signed perl binary would open a  
hole the size of a barn door in your scheme, I think.

Cheers,
Kyle Moffett