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Re: XFree86 insecurity (abc123)


From: slapic () FIDO HU (Czako Krisztian)
Date: Tue, 25 Nov 1997 00:23:06 +0100


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[Your antispam program is a bit too paranoid I think...]

On Fri, 21 Nov 1997, shegget wrote:

Program:   XF86_*, the XFree86 servers (XF86_SVGA, XF86_VGA16, ...)
Version:   Tested on XFree86 3.3.1 (current), 3.2.9 and 3.1.2.
           Other versions as well.
OS:        All

Except Debian Linux, where the X servers aren't setuid root!

Impact:    The XFree86 servers let you specify an alternate configuration
           file and do not check whether you have rights to read it.
           Any user can read files with root permissions.

One more reason to use Debian :)

On my Debian 1.3.1 + hamm upgarde (XFree86 3.3.1):
bash-2.00$ ls -l /usr/X11R6/bin/X*
- -rwsr-xr-x   1 root     root         4728 Oct 18 06:58 /usr/X11R6/bin/X
- -rwxr-xr-x   1 root     root       820544 Jun 20 16:41 /usr/X11R6/bin/XF86Setup
- -rwxr-xr-x   1 root     root      2313580 Jul 17 15:33 /usr/X11R6/bin/XF86_S3
- -rwxr-xr-x   1 root     root      1816864 Jun 20 16:41 /usr/X11R6/bin/XF86_VGA16

bash-2.00$ cd /usr/X11R6/bin/
bash-2.00$ ./X
X: you are not authorised to run the X server

bash-2.00$ dpkg -S /usr/X11R6/bin/X
xbase: /usr/X11R6/bin/X

So I suggest using this wrapper on all systems where possible.
Another solution can be running xdm, and make xdm to start the X server.
In this case you don't need the X server to be setuid root.

Slapic

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