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AUSCERT External Security Bulletin Redistribution
ESB-2018.1598
Several vulnerabilities in NPF
28 May 2018
===========================================================================
AusCERT Security Bulletin Summary
---------------------------------
Product: kernel
Publisher: NetBSD
Operating System: NetBSD
Impact/Access: Denial of Service -- Remote/Unauthenticated
Reduced Security -- Remote/Unauthenticated
Resolution: Patch/Upgrade
Original Bulletin:
ftp://ftp.netbsd.org/pub/NetBSD/security/advisories/NetBSD-SA2018-008.txt.asc
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NetBSD Security Advisory 2018-008
=================================
Topic: Several vulnerabilities in NPF
Version: NetBSD-current: source prior to Thu, Mar 22nd 2018
NetBSD 7.1 - 7.1.2: affected
NetBSD 7.0 - 7.0.2: affected
NetBSD 6.1 - 6.1.5: affected
NetBSD 6.0 - 6.0.6: affected
Severity: Remote Rule Bypass, Remote Memory Corruption
Fixed: NetBSD-current: Thu, Mar 22nd 2018
NetBSD-7-1 branch: Mon, May 14th 2018
NetBSD-7-0 branch: Mon, May 14th 2018
NetBSD-7 branch: Mon, May 14th 2018
NetBSD-6-1 branch: Thu, May 17th 2018
NetBSD-6-0 branch: n/a
NetBSD-6 branch: Thu, May 17th 2018
Teeny versions released later than the fix date will contain the fix.
Please note that NetBSD releases prior to 6.0 are no longer supported.
It is recommended that all users upgrade to a supported release.
Abstract
========
Several vulnerabilities were discovered in NPF:
1) Integer overflow when parsing IPv6 headers.
2) Use-after-free when handling ICMP packets.
Issue 2 will not be fixed in the netbsd-6-0 branch.
Technical Details
=================
1) An integer overflow could be triggered when NPF was parsing IPv6
options of a packet. This overflow could result in a header length
that was smaller than expected, which could allow an incoming
packet to bypass L4 rules.
2) A use-after-free could occur when NPF was parsing an ICMP packet.
This could result in a rule bypass, a panic, or unexpected
behavior.
Solutions and Workarounds
=========================
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 summarize how to upgrade your
kernel. In these instructions, replace:
ARCH with your architecture (from uname -m),
KERNCONF with the name of your kernel configuration file and
VERSION with the file version below
File versions containing the fixes:
FILE HEAD netbsd-7 netbsd-7-0 netbsd-7-1
---- ---- -------- ---------- ----------
src/sys/net/npf/npf.h
1.55 1.47.2.1 1.47.6.1 1.47.12.1
src/sys/net/npf/npf_inet.c
1.45 1.32.2.3 1.32.6.1 1.32.10.1
src/sys/net/npf/npf_alg_icmp.c
1.29 1.23.2.1 1.23.6.1 1.23.12.1
FILE netbsd-6 netbsd-6-0 netbsd-6-1
---- -------- ---------- ----------
src/sys/net/npf/npf.h
1.14.2.13 1.14.2.6.4.2 1.14.2.12.2.1
src/sys/net/npf/npf_inet.c
1.10.4.11 n/a 1.10.4.9.2.2
src/sys/net/npf/npf_alg_icmp.c
1.8.4.8 n/a 1.8.4.7.2.1
To update from CVS, re-build, and re-install the kernel:
# cd src
# cvs update -d -P -r VERSION sys/net/npf/npf.h
# cvs update -d -P -r VERSION sys/net/npf/npf_inet.c
# cvs update -d -P -r VERSION sys/net/npf/npf_alg_icmp.c
# ./build.sh 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:
http://www.NetBSD.org/guide/en/chap-kernel.html
Thanks To
=========
Maxime Villard for finding and fixing these issues.
Revision History
================
2018-05-24 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
http://ftp.NetBSD.org/pub/NetBSD/security/advisories/NetBSD-SA2018-008.txt.asc
Information about NetBSD and NetBSD security can be found at
http://www.NetBSD.org/ and http://www.NetBSD.org/Security/ .
Copyright 2018, The NetBSD Foundation, Inc. All Rights Reserved.
Redistribution permitted only in full, unmodified form.
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