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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2015.2160 Multiple integer overflows in expat (libbsdxml) XML parser 19 August 2015 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: expat Publisher: FreeBSD Operating System: FreeBSD Impact/Access: Execute Arbitrary Code/Commands -- Remote with User Interaction Denial of Service -- Remote with User Interaction Resolution: Patch/Upgrade CVE Names: CVE-2015-1283 Reference: ASB-2015.0073 ESB-2015.1959 ESB-2015.1957 ESB-2015.1954 Original Bulletin: https://security.FreeBSD.org/advisories/FreeBSD-SA-15:20.expat.asc - --------------------------BEGIN INCLUDED TEXT-------------------- - -----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) iQIcBAEBCgAGBQJV05AOAAoJEO1n7NZdz2rnRPUP/2L0kectacl6IWOOeGFt6QgG eRjZ6F53GqOYG3eW6tM71y+Vbeld+HkcMMgsckO4PM1vJg9AbKEJ56DmvGvFQepC TBBcbg++VHOB2jilKh/meOiF0sUqwcpSTwOdRREfWTAMXNS5te7kcpuykZoi4R1x LupCmRxQtM3taztw0AA/5AVRurmy+i6P9xuUnhGULyCcoi56VI1WvrpTk2KHbi7V T5f/Xwf2hPfznJVoxvPjY9YoOlD2Fql0Dc51clJOQ82l9VVD+lP4ISoJmwLqFPKA K4ZpiutMkoLda1er4lNaxsH4Ec7Oey4Dx2xpq1/JmQ9tP98Mtq4oaXNZAGminlET rNoLOWR72Gg+NEh7Y+Yuu0K3zFmzLLm1pMjYfuIUaseT2qY7CE+qwm58kG6NvC53 fF+BwofOSaVNX/uzQnbP0iMJbewKXpqNO21CkdaapZVG+sXn8BZF3S1QDAWPaNwV cJT9agijNG6pNUESNZcgY0ow/n4B8J+wWwA1KWzBgbedzj0yG8rsmulkCZEpt1hU 4uHR62Ktvd2IecoRn2gptA6SkpxHHJhzG8uKvDFq9vvzZko31rc3ttLI/Bb5P1QZ wqn1hp1sy9hEpoGxFQlYJj4msahR4P7vTt+0cN4dSVwwg08Xbq1TL4b077BR1ZbR ymv8Cnwn7Kg5NRBS2GBD =4h4f - -----END PGP SIGNATURE----- - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. 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It may not be updated when updates to the original are made. If downloading at a later date, it is recommended that the bulletin is retrieved directly from the author's website to ensure that the information is still current. Contact information for the authors of the original document is included in the Security Bulletin above. If you have any questions or need further information, please contact them directly. Previous advisories and external security bulletins can be retrieved from: http://www.auscert.org.au/render.html?cid=1980 =========================================================================== Australian Computer Emergency Response Team The University of Queensland Brisbane Qld 4072 Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). 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