OpenBSD and NetBSD permit usermode code to kill the display server and write to the X.Org /dev/xf86 device, which allows local users with root privileges to reduce securelevel by replacing the System Management Mode (SMM) handler via a write to an SMRAM address within /dev/xf86 (aka the video card memory-mapped I/O range), and then launching the new handler via a System Management Interrupt (SMI), as demonstrated by a write to Programmed I/O port 0xB2.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Netbsd | Netbsd | 2.0.4 (including) | 2.0.4 (including) |
| Openbsd | Openbsd | * | * |
References
- http://lists.freedesktop.org/archives/xorg/2004-June/000927.html
- http://www.cansecwest.com/slides06/csw06-duflot.ppt
- http://www.securityfocus.com/archive/1/454379/100/0/threaded
- http://www.securityfocus.com/archive/1/454510/100/0/threaded
- http://www.securityfocus.com/archive/1/454706/100/0/threaded
- http://www.ssi.gouv.fr/fr/sciences/fichiers/lti/cansecwest2006-duflot-paper.pdf
- http://lists.freedesktop.org/archives/xorg/2004-June/000927.html
- http://www.cansecwest.com/slides06/csw06-duflot.ppt
- http://www.securityfocus.com/archive/1/454379/100/0/threaded
- http://www.securityfocus.com/archive/1/454510/100/0/threaded
- http://www.securityfocus.com/archive/1/454706/100/0/threaded
- http://www.ssi.gouv.fr/fr/sciences/fichiers/lti/cansecwest2006-duflot-paper.pdf