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Category:   OS (UNIX)  >   FreeBSD Kernel Vendors:   FreeBSD
FreeBSD hostapd Validation Flaw Lets Remote Users Deny Service
SecurityTracker Alert ID:  1027808
SecurityTracker URL:
CVE Reference:   CVE-2012-4445   (Links to External Site)
Date:  Nov 23 2012
Impact:   Denial of service via network
Fix Available:  Yes  Vendor Confirmed:  Yes  
Version(s): FreeBSD 8.0, 9.0, 9.1
Description:   A vulnerability was reported in FreeBSD hostapd. A remote user can cause denial of service conditions.

The hostapd utility does not validate the length of EAP-TLS messages. A remote user can send specially crafted EAP-TLS messages to cause the target hostapd service to crash.

Impact:   A remote user can cause the target hostapd service to crash.
Solution:   FreeBSD has issued a fix.

The FreeBSD advisory is available at:

Vendor URL: (Links to External Site)
Cause:   Input validation error

Message History:   None.

 Source Message Contents

Subject:  FreeBSD Security Advisory FreeBSD-SA-12:07.hostapd

Hash: SHA1

FreeBSD-SA-12:07.hostapd                                    Security Advisory
                                                          The FreeBSD Project

Topic:          Insufficient message length validation for EAP-TLS messages

Category:       contrib
Module:         wpa
Announced:      2012-11-22
Credits:        Timo Warns, Jouni Malinen
Affects:        FreeBSD 8.0 and later.
Corrected:      2012-11-22 22:52:15 UTC (RELENG_8, 8.3-STABLE)
                2012-11-22 22:52:15 UTC (RELENG_8_3, 8.3-RELEASE-p5)
                2012-11-22 22:52:15 UTC (RELENG_9, 9.1-PRERELEASE)
                2012-11-22 22:52:15 UTC (RELENG_9_0, 9.0-RELEASE-p5)
                2012-11-22 22:52:15 UTC (RELENG_9_1, 9.1-RC1-p1)
                2012-11-22 22:52:15 UTC (RELENG_9_1, 9.1-RC2-p1)
                2012-11-22 22:52:15 UTC (RELENG_9_1, 9.1-RC3-p1)
CVE Name:       CVE-2012-4445

For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit <URL:>.

I.   Background

The hostapd utility is an authenticator for IEEE 802.11 networks.  It
provides full support for WPA/IEEE 802.11i and can also act as an IEEE
802.1X Authenticator with a suitable backend Authentication Server
(typically FreeRADIUS).

EAP-TLS is the original, standard wireless LAN EAP authentication
protocol defined in RFC 5216.  It uses PKI to secure communication to a
RADIUS authentication server or another type of authentication server.

II.  Problem Description

The internal authentication server of hostapd does not sufficiently
validate the message length field of EAP-TLS messages.

III. Impact

A remote attacker could cause the hostapd daemon to abort by sending
specially crafted EAP-TLS messages, resulting in a Denial of Service.

IV.  Workaround

No workaround is available, but systems not running hostapd are not

Note that for FreeBSD 8.x systems, the EAP-TLS authentication method
is not enabled by default.  Systems running FreeBSD 8.x are only
affected when hostapd is built with -DEAP_SERVER and as such, binary
installations from the official release are not affected.

V.   Solution

Perform one of the following:

1) Upgrade your vulnerable system to 8-STABLE or 9-STABLE, or to
the RELENG_8_3, or RELENG_9_0 security branch dated after the
correction date.

2) To update your vulnerable system via a source code patch:

The following patches have been verified to apply to FreeBSD 8.3
and 9.0 systems.

a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.

[FreeBSD 8.x]
# fetch
# fetch

[FreeBSD 9.x]

# fetch
# fetch

b) Execute the following commands as root:

# cd /usr/src
# patch < /path/to/patch

Recompile the operating system using buildworld and installworld as
described in <URL:>.

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

Systems running 8.3-RELEASE, 9.0-RELEASE, 9.1-RC1, 9.1-RC2, or 9.1-RC3
on the i386 or amd64 platforms can be updated via the
freebsd-update(8) utility:

# freebsd-update fetch
# freebsd-update install

VI.  Correction details

The following list contains the revision numbers of each file that was
corrected in FreeBSD.


Branch/path                                                      Revision
- -------------------------------------------------------------------------
stable/8/                                                     r<revision>
releng/8.3/                                                   r<revision>
stable/9/                                                     r<revision>
releng/9.0/                                                   r<revision>
releng/9.1/                                                   r<revision>
- -------------------------------------------------------------------------

VII. References

The latest revision of this advisory is available at
Version: GnuPG v1.4.9

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