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FreeBSD-SA-23:11.wifi                                       Security Advisory
                                                          The FreeBSD Project

Topic:          Wi-Fi encryption bypass

Category:       core
Module:         net80211
Announced:      2023-09-06
Credits:        See the paper linked in the References section.
Affects:        All supported versions of FreeBSD.
Corrected:      2023-06-26 12:02:00 UTC (stable/13, 13.2-STABLE)
                2023-09-06 17:13:25 UTC (releng/13.2, 13.2-RELEASE-p3)
                2023-06-26 12:30:23 UTC (stable/12, 12.4-STABLE)
                2023-09-06 17:38:34 UTC (releng/12.4, 12.4-RELEASE-p5)
CVE Name:       CVE-2022-47522

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

FreeBSD's net80211 kernel subsystem provides infrastructure and drivers
for IEEE 802.11 wireless (Wi-Fi) communications.  Wi-Fi communications rely
on both unicast and multicast keys to secure transmissions.

II.  Problem Description

The net80211 subsystem would fallback to the multicast key for unicast
traffic in the event the unicast key was removed.  This would result in
buffered unicast traffic being exposed to any stations with access to the
multicast key.

III. Impact

As described in the "Framing Frames: Bypassing Wi-Fi Encryption by
Manipulating Transmit Queues" paper, an attacker can induce an access point
to buffer frames for a client, deauthenticate the client (causing the unicast
key to be removed from the access point), and subsequent flushing of the
buffered frames now encrypted with the multicast key.  This would give the
attacker access to the data.

IV.  Workaround

No workaround is available.  Systems not using Wi-Fi are not affected.

V.   Solution

Upgrade your vulnerable system to a supported FreeBSD stable or
release / security branch (releng) dated after the correction date
and reboot

Perform one of the following:

1) To update your vulnerable system via a binary patch:

Systems running a RELEASE version of FreeBSD on the amd64, i386, or
(on FreeBSD 13 and later) arm64 platforms can be updated via the
freebsd-update(8) utility:

# freebsd-update fetch
# freebsd-update install
# shutdown -r +10min "Rebooting for a security update"

2) 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-23:11/wifi.patch
# fetch https://security.FreeBSD.org/patches/SA-23:11/wifi.patch.asc
# gpg --verify wifi.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

This issue is corrected by the corresponding Git commit hash or Subversion
revision number in the following stable and release branches:

Branch/path                             Hash                     Revision
- -------------------------------------------------------------------------
stable/13/                              6c9bcecfb296    stable/13-n255680
releng/13.2/                            7f34ee7cc56b  releng/13.2-n254632
stable/12/                                                        r373115
releng/12.4/                                                      r373187
- -------------------------------------------------------------------------

For FreeBSD 13 and later:

Run the following command to see which files were modified by a
particular commit:

# git show --stat <commit hash>

Or visit the following URL, replacing NNNNNN with the hash:

<URL:https://cgit.freebsd.org/src/commit/?id=NNNNNN>

To determine the commit count in a working tree (for comparison against
nNNNNNN in the table above), run:

# git rev-list --count --first-parent HEAD

For FreeBSD 12 and earlier:

Run the following command to see which files were modified by a particular
revision, replacing NNNNNN with the revision number:

# 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://papers.mathyvanhoef.com/usenix2023-wifi.pdf>

<URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-47522>

The latest revision of this advisory is available at
<URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-23:11.wifi.asc>
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