-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 ============================================================================= FreeBSD-SA-19:06.pf Security Advisory The FreeBSD Project Topic: ICMP/ICMP6 packet filter bypass in pf Category: contrib Module: pf Announced: 2019-05-14 Credits: Synacktiv Affects: All supported versions of FreeBSD Corrected: 2019-03-21 14:17:10 UTC (stable/12, 12.0-STABLE) 2019-05-14 23:12:22 UTC (releng/12.0, 12.0-RELEASE-p4) 2019-03-21 14:17:12 UTC (stable/11, 11.3-PRERELEASE) 2019-05-14 23:12:22 UTC (releng/11.2, 11.2-RELEASE-p10) CVE Name: CVE-2019-5598 For general information regarding FreeBSD Security Advisories, including descriptions of the fields above, security branches, and the following sections, please visit <URL:https://security.FreeBSD.org/>. I. Background pf(4) is an Internet Protocol packet filter originally written for OpenBSD. In addition to filtering packets, it also has packet normalization capabilities. II. Problem Description States in pf(4) let ICMP and ICMP6 packets pass if they have a packet in their payload matching an existing condition. pf(4) does not check if the outer ICMP or ICMP6 packet has the same destination IP as the source IP of the inner protocol packet. III. Impact A maliciously crafted ICMP/ICMP6 packet could bypass the packet filter rules and be passed to a host that would otherwise be unavailable. IV. Workaround No workaround is available. V. Solution Perform one of the following: 1) Upgrade your vulnerable system to a supported FreeBSD stable or release / security branch (releng) dated after the correction date. Afterwards, reboot the system. 2) To update your vulnerable system via a binary patch: Systems running a RELEASE version of FreeBSD on the i386 or amd64 platforms can be updated via the freebsd-update(8) utility: # freebsd-update fetch # freebsd-update install Afterwards, reboot the system. 3) To update your vulnerable system via a source code patch: The following patches have been verified to apply to the applicable FreeBSD release branches. a) Download the relevant patch from the location below, and verify the detached PGP signature using your PGP utility. # fetch https://security.FreeBSD.org/patches/SA-19:06/pf.patch # fetch https://security.FreeBSD.org/patches/SA-19:06/pf.patch.asc # gpg --verify pf.patch.asc b) Apply the patch. Execute the following commands as root: # cd /usr/src # patch < /path/to/patch c) Recompile your kernel as described in <URL:https://www.FreeBSD.org/handbook/kernelconfig.html> and reboot the system. VI. Correction details The following list contains the correction revision numbers for each affected branch. Branch/path Revision - ------------------------------------------------------------------------- stable/12/ r345377 releng/12.0/ r347593 stable/11/ r345378 releng/11.2/ r347593 - ------------------------------------------------------------------------- To see which files were modified by a particular revision, run the following command, replacing NNNNNN with the revision number, on a machine with Subversion installed: # svn diff -cNNNNNN --summarize svn://svn.freebsd.org/base Or visit the following URL, replacing NNNNNN with the revision number: <URL:https://svnweb.freebsd.org/base?view=revision&revision=NNNNNN> VII. References <URL:https://www.synacktiv.com/posts/systems/icmp-reachable.html> <URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-5598> The latest revision of this advisory is available at <URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-19:06.pf.asc> -----BEGIN PGP SIGNATURE----- iQKTBAEBCgB9FiEE/A6HiuWv54gCjWNV05eS9J6n5cIFAlzbTsdfFIAAAAAALgAo aXNzdWVyLWZwckBub3RhdGlvbnMub3BlbnBncC5maWZ0aGhvcnNlbWFuLm5ldEZD MEU4NzhBRTVBRkU3ODgwMjhENjM1NUQzOTc5MkY0OUVBN0U1QzIACgkQ05eS9J6n 5cIjXA/9FevC+Ygihzb0J9MN0znEM883dk5sPCSvMwiivsNRkDMXreYqPXU+Fkt0 iV1OZ8tKwKAihm+iGJ5mzS5l40wWF1oDcqJrC0myICdvreraoJKZvTLhgGIBqKkE b8yIuzPueWdnnudoAzTV38RhyaP2aOb44OMUNPQZsEB/6hHsNvp9m6yAua/F+x9+ N9J38Y/C6udsNfhqDeuCI4G8yiN33XfFiRbF+31rt3s0rUm6KGNsJanJe8dNAEvE DN4tA4+MORnQ7QTLgOobGuLFhWJ2urC6psH8duO72hcSTzSkTZpxrC3f6SW8RlZ+ Pbr4LZ6FA3bZp/sCmWPOot94hotBDr03MZwrxURokeDHZU1nUBsw0rmTG4aypujl JrGPOAp89TtqrR0zV8DhpGO/RWoBeMDf7ZGvIplOIEF5rijQWEyC5pnYlBKPfSdm UTxcN9RoJCfz7O4KLAAqhHiuu6xc+CqlQH1dvyLbqGVv9LzUQlziTNsbQ4cGryuj g1TztU0VfpvHDkAKBh0iHwkoUqDSut3K19rFAQ3zkM/EodqSTkE1OG77pmsjYaVq AfcnN/se8lklq0lKi3BwNvVIWTjhMAwY63otVxvVD4wrJrgQH8NKgOeYuGBreXeW Uv569bIhR0/vsyGJK/SMKxBiAGfzkE7LqDMJqdXLsompX97nOwI= =m3as -----END PGP SIGNATURE-----