Re: hard links create local DoS vulnerability and security problems

Richard B. Johnson
2003-11-24T18:11:10Z

On Mon, 24 Nov 2003 splite@purdue.edu wrote:

> On Mon, Nov 24, 2003 at 06:57:41PM +0100, Jakob Lell wrote:
> > [...]
> > Setuid-root binaries also work in a home directory.
> > You can try it by doing this test:
> > ln /bin/ping $HOME/ping
> > $HOME/ping localhost
> > [...]
>
> That's why you don't put user-writable directories on the root or /usr
> partitions. (For extra points, mount your /tmp and /var/tmp partitions
> nodev,nosuid.) Seriously guys, this is Unix Admin 101, not a major new
> security problem.
>

And if the inode that was referenced in the root-owned directory
was deleted, it would no longer function as setuid root.

Cheers,
Dick Johnson
Penguin : Linux version 2.4.22 on an i686 machine (797.90 BogoMips).
Note 96.31% of all statistics are fiction.