full-disclosure - Security hole in Confixx backup script

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From: dirk at pirschel.de (Dirk Pirschel)
Subject: Security hole in Confixx backup script

Hi,

* Valdis.Kletnieks@...edu wrote on Mon, 09 Aug 2004 at 21:26 -0400:
> On Tue, 10 Aug 2004 02:16:24 +0200, Thomas Loch said:

> > What if someone creates a shell script [...] and sets the SetUID
> > flag. Then he makes a backup of that file and restores the backup
> > while he prevents the chown-command anyhow. All files will remain
> > "root".

The race condition between "tar xzf" and "chmod -R" can be won, if there
are many files or simply one big file in the archives.  A quick "mv"
should prevent the suid programm from beeing chown()ed.

> You'd probably have to work a *little* harder than a shell script - most
> Unixoid systems don't allow the execution of a setUID shell script due to
> various and sundry race conditions involved (which is why 'suidperl' exists).
> Other than that, you're on the right track.. ;) 

What about a suid bash? ;-)

-Dirk

-- 
Linux: Who needs Windows and Gates in a world without walls and fences?
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