replace uname -a informational string

Michael B. Eichorn ike at michaeleichorn.com
Fri Oct 23 23:18:06 UTC 2015


On Fri, 2015-10-23 at 15:55 -0700, Karl Young wrote:
> 
> O. Hartmann(ohartman at zedat.fu-berlin.de)@2015.10.23 22:54:24 +0200:
> > Am Fri, 23 Oct 2015 13:45:25 -0400
> > "Michael B. Eichorn" <ike at michaeleichorn.com> schrieb:
> > 
> > 
> > First of all: Thank you very much for your concerns and answers.
> > 
> > > On Fri, 2015-10-23 at 09:08 +0200, O. Hartmann wrote:
> > > > For security purposes, I need to replace the informations given
> > > > by
> > > > "uname -a"
> > > > to hode the kernel build system, name et cetera.  
> > > 
> > > I presume you intendend 'hide' here?
> > > 
> > > If you want to scrub a binaries of _all_ information about the
> > > building
> > > system this is a problem Debian is actively working on called
> > > 'reproducible builds' but is not possible today.
> > > 
> > > https://reproducible.debian.net
> > > 
> > > If you want to hide the hostname, why not just build with a
> > > different
> > > hostname set?
> > 
> > Because it is not only the hostname, uname reveals the target host,
> > date and OS version.
> > 
> > In our case, the image ist built on a dedicated host for a security
> > appliabce based on
> > NanoBSD and I'd like to hide the OS type, the OS name, the build box'
> > name and the build
> > date. 
> 
> Perhaps you could mv or rm /usr/bin/uname and replace it with your own
> script or binary that outputs whatever you want it to.
> 
> -karl

To make that work you would need to do a lot of work to prevent the user
from using a copy of the original uname (or something similar). The
information is actually in the kernel itself, uname is just mechanism to
report it.

And then there are tools like strings...
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