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Date: Fri, 05 Dec 2014 20:30:55 -0500
From: Daniel Micay <danielmicay@...il.com>
To: oss-security@...ts.openwall.com
Subject: Re: Re: Offset2lib: bypassing full ASLR on 64bit Linux

On 05/12/14 08:18 PM, Andy Lutomirski wrote:
> On 12/05/2014 04:44 PM, Hanno Böck wrote:
>> On Fri, 05 Dec 2014 17:43:44 -0500
>> Daniel Kahn Gillmor <dkg-QLrU/DhXBlmnlhUoGqYIEF6hYfS7NtTn@...lic.gmane.org> wrote:
>>
>>> i couldn't find a reference to this in the nautilus bugtracker, so i
>>> just posted:
>>>
>>>  https://bugzilla.gnome.org/show_bug.cgi?id=741183
>>
>> I tried to dig into this a bit. I'm not really sure, but based on the
>> output I assume nautilus is relying on file or libmagic to assess the
>> file type.
>>
>> And that's what fails:
>> $ file --mime-type pie
>> pie: application/x-sharedlib
>>
>>
>> It seems there is no really easy way to separate executables from
>> shared libraries and whether this should be considered a bug in
>> file/libmagic. The only thing I quickly found that would be possible is
>> searching if a SONAME is present. libmagic uses some "magic" file
>> format to parse files, I don't know if that's capable of such complex
>> parsing.
>>
> 
> Why does gcc and/or ld write a non-zero entry point?  If they didn't,
> that would be an easy way to check.
> 
> --Andy

There are some libraries like glibc's /usr/lib/libc.so.6 with valid
entry points, so file would still have trouble disambiguating that way.

I don't really think this is a problem for libmagic/file to solve, if
it's really a problem at all. Nautilus could just remove support for
executing traditional executables too... using CLI utilities that way
isn't going to work out and GUI ones have desktop files.


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