Security-Announce archive
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Old Index]
NetBSD Security Advisory 2018-004: Remote Memory Corruption in IPv6
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
NetBSD Security Advisory 2018-004
=================================
Topic: Remote Memory Corruption in IPv6
Version: NetBSD-current: source prior to Tue, Jan 30th 2018
NetBSD 7.1: affected
NetBSD 7.0 - 7.0.2: affected
NetBSD 6.1 - 6.1.4: affected
NetBSD 6.0 - 6.0.5: affected
Severity: Remote DoS, Remote Memory Corruption
Fixed: NetBSD-current: Tue, Jan 30th 2018
NetBSD-7-1 branch: Tue, Jan 30th 2018
NetBSD-7-0 branch: Tue, Jan 30th 2018
NetBSD-7 branch: Tue, Jan 30th 2018
NetBSD-6-1 branch: Tue, Jan 30th 2018
NetBSD-6-0 branch: Tue, Jan 30th 2018
NetBSD-6 branch: Tue, Jan 30th 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
========
A mistake in the way received IPv6 packets are handled allowed an attacker
to remotely trigger a memory corruption.
Technical Details
=================
When a packet is received, the kernel stores it in memory as chain of mbufs.
An mbuf is basically a block of contiguous memory.
A function, located deep into the IPv6 entry point, was not performing the
necessary checks when treating a received IPv6 packet. It was parsing the
IPv6 options assuming they were located in the first mbuf of the chain, but
this assumption was incorrect. Therefore, it was possible for this function
to return a pointer that pointed to an area located after the first mbuf.
This pointer was then either read from, or written to with one byte that
could be controlled by the packet.
It has been demonstrated that by sending a special combination of nested
IPv6 fragments, this bug could be exploited remotely, and could allow an
attacker to cause the kernel to behave unexpectedly because random areas of
memory were overwritten. It is not clear whether this attack could be turned
to a code execution attack.
The PF firewall can mitigate this particular attack, because it rejects
nested IPv6 fragments by default. NPF does not reject such fragments by
default. The status of IPF in this regard has not been investigated. It is
possible that other vectors than IPv6 fragments could trigger this
vulnerability.
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/netinet6/frag6.c
1.65 1.55.4.1 1.55.6.1 1.55.10.1
src/sys/netinet6/ip6_input.c
1.187 1.149.2.2 1.149.2.1.2.1 1.149.2.1.6.1
src/sys/netinet6/ip6_var.h
1.78 1.62.2.2 1.62.2.1.2.1 1.62.2.1.6.1
src/sys/netinet6/raw_ip6.c
1.160 1.136.2.2 1.136.6.1 1.136.2.1.2.1
FILE netbsd-6 netbsd-6-0 netbsd-6-1
---- -------- ---------- ----------
src/sys/netinet6/frag6.c
1.52.2.3 1.52.2.1.4.2 1.52.2.2.2.1
src/sys/netinet6/ip6_input.c
1.136.2.2 1.136.6.2 1.136.8.2
src/sys/netinet6/ip6_var.h
1.58.2.2 1.58.6.2 1.58.8.2
src/sys/netinet6/raw_ip6.c
1.109.2.1 1.109.6.1 1.109.8.1
src/sys/netinet6/ah_input.c
1.59.8.1 1.59.12.1 1.59.14.1
src/sys/netinet6/esp_input.c
1.50.8.1 1.50.12.1 1.50.14.1
src/sys/netinet6/ipcomp_input.c
1.38.8.1 1.38.12.1 1.38.14.1
Note: for NetBSD-6, there are three more files that contain the fix.
To update from CVS, re-build, and re-install the kernel:
# cd src
# cvs update -d -P -r VERSION sys/netinet6/frag6.c
# cvs update -d -P -r VERSION sys/netinet6/ip6_input.c
# cvs update -d -P -r VERSION sys/netinet6/ip6_var.h
# cvs update -d -P -r VERSION sys/netinet6/raw_ip6.c
If you run NetBSD-6:
# cvs update -d -P -r VERSION sys/netinet6/ah_input.c
# cvs update -d -P -r VERSION sys/netinet6/esp_input.c
# cvs update -d -P -r VERSION sys/netinet6/ipcomp_input.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 the issue.
Revision History
================
2018-02-12 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-SA2018-0XX.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.
-----BEGIN PGP SIGNATURE-----
iQIcBAEBAgAGBQJage/nAAoJEAZJc6xMSnBuCSAQAI+h5bvTOzT8Ezn6NCNR6k+8
w93BPxBFCFluJuKDY4e33Ndt04gZYz7FXPAKti8XWLJ3316pi2bXwO0BwGUwI1V9
b9TWWlwPka9cVDaKm3A6GZK4iR8KuKVOWK8Q+V+fF/iRpoohtGrpse9jhtZk0yVA
nRsc7QfPr134eVqwE0nZu9waWgRYPBAPcARIG/aby8oXpQt/gnj66IKqXKPaJaLZ
A0l77Rybns03ihNzaOKOwA5iVgoXHt0G9iN4HDosEpsefHTxq7kv3TfqY7I6uAqK
4KZ0OjEnhlokUvn3CF+tx+1tSkwFgr35zjKxutqgbWZXQRMvvmk0b7PWeVoAhwjU
uS6ArCZgvwk7/OVkNHqDxz+qAjo8zmfCC1ZBq6ZdYn8LoYnbpO5RUF7vSlci7zAe
RqPHJ6k4YvzE/+Z+z4bc5zTtOIrlzQXWoHhzua3E8EvvAp81N8s9I7j5Li+sFrLx
06vbHrSN0o4dYlHxbwOJ9xUVggubnGMlay3ArDTGtfihTkAlMsjs/AGZHHIprIl3
MZhm5WX0gj2PLhtd2ByL6nls05v3o0rFSVDHTet/ff+pcvf3zb0wmoWsjvmHbaCx
FPqb9DbQ2Za38zSUDZy1gppa3S3EIKV9aYnUbhWmoxMr+5pD5FTwsmdVu/YraU5J
LWEtvindpvyNBjz+/izI
=QoMB
-----END PGP SIGNATURE-----
Home |
Main Index |
Thread Index |
Old Index