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

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