What if someone creates a shell script that simply "cat /etc/shadow" 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".
Including the script. The execution of this script will print out the
shadowed encrypted passwords. This can even be used to chmod the shadow file
and make it readable for everyone
On Monday 09 August 2004 19:17, Dirk Pirschel wrote:
> Hi,
>
> * Dirk Pirschel wrote on Mon, 02 Aug 2004 at 13:00 +0200:
> > A user might use the restore funktion to change the ownership of
> > target files to his own.
>
> The restore script runs with root privileges. It unpacks the archive,
> and then executes "chown -R $user" in the destination directory
> ($HOME/html or $HOME/files). Before running the restore script, an
> attacker can make hardlinks to files not owned by himself. The
> ownership of these files will be changed.
>
> On some badly administered systems there is only one disk partion, so it
> is possible to make a hardlink to /etc/shdadow within $HOME.
>
> -Dirk
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Received on Aug 10 2004
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