Home / vulnerabilities FreeBSD Security Advisory - expat Integer Overflows
Posted on 22 August 2015
Source : packetstormsecurity.org Link
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512
=============================================================================
FreeBSD-SA-15:20.expat Security Advisory
The FreeBSD Project
Topic: Multiple integer overflows in expat (libbsdxml) XML parser
Category: contrib
Module: libbsdxml
Announced: 2015-08-18
Affects: All supported versions of FreeBSD.
Corrected: 2015-08-18 19:30:05 UTC (stable/10, 10.2-STABLE)
2015-08-18 19:30:35 UTC (releng/10.1, 10.1-RELEASE-p18)
2015-08-18 19:30:17 UTC (releng/10.2, 10.2-RC3-p1)
2015-08-18 19:30:17 UTC (releng/10.2, 10.2-RELEASE-p1)
2015-08-18 19:30:05 UTC (stable/9, 9.3-STABLE)
2015-08-18 19:30:35 UTC (releng/9.3, 9.3-RELEASE-p23)
CVE Name: CVE-2015-1283
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
Expat is an XML parser library written in C. It is a stream-oriented
parser in which an application registers handlers for things the parser
might find in the XML document (like start tags).
The FreeBSD base system ships libexpat as libbsdxml for components that
need to parse XML data. Some of these applications use the XML parser
on trusted data from the kernel, for instance the geom(8) configuration
utilities, while other applications, like tar(1), cpio(1), svnlite(1)
and unbound-anchor(8), may use the XML parser on input from network or
the user.
II. Problem Description
Multiple integer overflows have been discovered in the XML_GetBuffer()
function in the expat library.
III. Impact
The integer overflows may be exploited by using specifically crafted XML
data and lead to infinite loop, or a heap buffer overflow, which results
in a Denial of Service condition, or enables remote attackers to execute
arbitrary code.
IV. Workaround
No workaround is available, but the problem is only exploitable when the
affected system needs to process data from an untrusted source.
Because the library is used by many third party applications, we advise
system administrators to check and make sure that they have the latest
expat version as well, and restart all third party services, or reboot
the system.
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.
A reboot is not required after updating the base 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
A reboot is not required after updating the base 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-15:20/expat.patch
# fetch https://security.FreeBSD.org/patches/SA-15:20/expat.patch.asc
# gpg --verify expat.patch.asc
b) Apply the patch. Execute the following commands as root:
# cd /usr/src
# patch < /path/to/patch
c) Recompile the operating system using buildworld and installworld as
described in <URL:https://www.FreeBSD.org/handbook/makeworld.html>.
The FreeBSD base system do not install daemons that uses the library,
therefore, a reboot is not required after updating the base system.
VI. Correction details
The following list contains the correction revision numbers for each
affected branch.
Branch/path Revision
- -------------------------------------------------------------------------
stable/9/ r286900
releng/9.3/ r286902
stable/10/ r286900
releng/10.1/ r286902
releng/10.2/ r286901
- -------------------------------------------------------------------------
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://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-1283>
The latest revision of this advisory is available at
<URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-15:20.expat.asc>
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2.1.7 (FreeBSD)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=4h4f
-----END PGP SIGNATURE-----
