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Re: Offset2lib: bypassing full ASLR on 64bit Linux


From: Seth Arnold <seth.arnold () canonical com>
Date: Fri, 5 Dec 2014 19:41:04 -0800

On Sat, Dec 06, 2014 at 01:44:31AM +0100, Hanno Böck wrote:
 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.

A far better mechanism in Nautilus would be to use execve(2) on the
pathname and see if it executes. Nautilus will never be good at guessing
which files are actually executable on a given system and it is ridiculous
for it to try to guess. It should just execute the selected file and if
that fails, report the failure to the user.

One goofy filemanager doing something silly ought not stop Mozilla from
shipping a safer Firefox.

Thanks

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