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Category:   OS (UNIX)  >   NetBSD Vendors:   NetBSD
NetBSD Buffer Overflow in iso(4) Lets Local Users Gain Root Privileges
SecurityTracker Alert ID:  1017832
SecurityTracker URL:
CVE Reference:   CVE-2007-1677   (Links to External Site)
Date:  Mar 30 2007
Impact:   Denial of service via local system, Execution of arbitrary code via local system, Root access via local system
Fix Available:  Yes  Vendor Confirmed:  Yes  
Version(s): 2.0, 2.1, 3.0, 3.1, 4.0_BETA2
Description:   A vulnerability was reported in NetBSD. A local user can obtain root privileges on the target system.

The system does not properly validate parameter length values in iso(4). A local user can trigger a buffer overflow and execute arbitrary code with root privileges on the target system or cause a kernel panic.

Several functions are affected, including clnp_route().

Christer Oberg of BitSec discovered and reported this vulnerability.

Impact:   A local user can obtain root privileges on the target system or cause a kernel panic.
Solution:   The vendor has issued a source code fix.

The NetBSD advisory is available at:

Vendor URL: (Links to External Site)
Cause:   Boundary error

Message History:   None.

 Source Message Contents

Subject:  NetBSD Security Advisory 2007-004: Insufficient length checking in

Hash: SHA1

		 NetBSD Security Advisory 2007-004

Topic:		Insufficient length checking in iso(4)

Version:	NetBSD-current:	source prior to March 29, 2007
		NetBSD 4.0_BETA2:	affected
		NetBSD 3.1:		affected
		NetBSD 3.0.*:		affected
		NetBSD 3.0:		affected
		NetBSD 2.1:		affected
		NetBSD 2.0.*:		affected
		NetBSD 2.0:		affected

Severity:	Local denial of service, Local root compromise

Fixed:		NetBSD-current:		March 29, 2007
		NetBSD-4 branch:	March 29, 2007
		NetBSD-3-1 branch:	March 29, 2007
		NetBSD-3-0 branch:	March 29, 2007
		NetBSD-3 branch:	March 29, 2007
		NetBSD-2-1 branch:	March 29, 2007	
		NetBSD-2-0 branch:	March 29, 2007
		NetBSD-2 branch:	March 29, 2007


Due to insufficient length checking in iso(4) it is possible for a local
user to cause an overflow, resulting in a local denial of service or 
local root compromise.

This vulnerability has been assigned CVE reference CVE-2007-1677.

Technical Details

A number of functions in the iso(4) code including clnp_route() do not
validate the length of arguments passed.  As a result of this a user
could supply a bad 'sockaddr' structure to clnp_route() via connect(2). 
This can lead to a root compromise if exploited correctly or a denial 
of service (panic).

Solutions and Workarounds

Kernels with the ISO protocol family support are affected, including the 
default GENERIC kernel install.  Users of affected NetBSD versions are highly 
recommended to upgrade their kernel.

Only kernels compiled with the following option are vulnerable to this issue:

	options ISO

As a temporary workaround recompile the kernel with the above option 
commented out.

For all NetBSD versions, you need to obtain fixed kernel sources,
rebuild and install the new kernel, and reboot the system.
The fixed source may be obtained from the NetBSD CVS repository.

The following instructions briefly summarise how to upgrade your
kernel.  In these instructions, replace:

   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 sys/netiso/clnp_subr.c
	# ./ kernel=KERNCONF
	# mv /netbsd /netbsd.old
	# cp sys/arch/ARCH/compile/obj/KERNCONF/netbsd /netbsd
	# shutdown -r now

For more information on how to do this, see:

Thanks To

Christer Oberg of BitSec discovered and reported this issue.
Christos Zoulas fixed the code.

Revision History

	2007-03-29	Initial release

More Information

Advisories may be updated as new information becomes available.
The most recent version of this advisory (PGP signed) can be found at

Information about NetBSD and NetBSD security can be found at and

Copyright 2007, The NetBSD Foundation, Inc.  All Rights Reserved.
Redistribution permitted only in full, unmodified form.

$NetBSD: NetBSD-SA2007-004.txt,v 1.1 2007/03/29 08:21:51 adrianp Exp $




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