Abstract

A local user that is allowed to use /dev/systrace can obtain root
access.

Technical Details

systrace_exit() did not check if the connection to systrace was owned by
the super user, and would set euid to 0 on exit.

Solutions and Workarounds

*** Patching from sources:

The fix for this issue is contained in the one file,
sys/kern/kern_systrace.c

The following table lists the fixed revisions and
dates of this file for each branch:

    CVS branch    revision    date
    ------------- ----------- ----------------
    HEAD          1.38        2004/04/17
    netbsd-2-0    1.37.2.1    2004/04/17

The following instructions describe how to upgrade your kernel
binaries by updating your source tree and rebuilding and installing a
new version of the kernel. In these instructions, replace:

BRANCH with the appropriate CVS branch (from the above table)
ARCH with your architecture (from uname -m), and
KERNCONF with the name of your kernel configuration file.

To update from CVS, re-build, and re-install the kernel:

# cd src
# cvs update -d -P -r BRANCH sys/kern/kern_systrace.c
# cd sys/arch/ARCH/conf
# config KERNCONF
# cd ../compile/KERNCONF
# make depend;make
# mv /netbsd /netbsd.old
# cp netbsd /
# reboot

* Binary Patch:

Binary patches are being provided, in the form of replacement
kernels built with the patches from the GENERIC kernel
configuration. If you use a custom kernel configuration, these
may not be suitable for you.

netbsd-current:

Releng does not compile -current kernels during a release cycle.
Users of -current are expected to be capable of upgrading from
sources.

netbsd-2-0:

Retrieve a kernel from:

ftp://releng.netbsd.org/pub/NetBSD-daily/netbsd-2-0/DATE/ARCH/binary/kernel/

Where DATE is any available DATE later than 2004-04-17

Thanks To

Stefan Esser for detection and notification
Niels Provos for patches

Revision History

2004-05-12 Initial release
                2004-05-12 Filename typo noted by Jim Bernard

More Information
 
Advisories may be updated as new information becomes available.
The most recent version of this advisory (PGP signed) can be found at
ftp://ftp.NetBSD.org/pub/NetBSD/security/advisories/NetBSD-SA2004-007.txt.asc

Information about NetBSD and NetBSD security can be found at
http://www.NetBSD.org/  and http://www.NetBSD.org/Security/ .

Copyright 2004, The NetBSD Foundation, Inc. All Rights Reserved.
Redistribution permitted only in full, unmodified form.