11 September 2013
Protect yourself against future threats.
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2013.1257 Kernel memory disclosure in sendfile(2) 11 September 2013 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: sendfile Publisher: FreeBSD Operating System: FreeBSD Impact/Access: Access Confidential Data -- Existing Account Resolution: Patch/Upgrade CVE Names: CVE-2013-5666 Original Bulletin: ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-13:11.sendfile.asc - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 ============================================================================= FreeBSD-SA-13:11.sendfile Security Advisory The FreeBSD Project Topic: Kernel memory disclosure in sendfile(2) Category: core Module: sendfile Announced: 2013-09-10 Credits: Ed Maste Affects: FreeBSD 9.2-RC1 and 9.2-RC2 Corrected: 2013-09-10 10:07:21 UTC (stable/9, 9.2-STABLE) 2013-09-10 10:08:20 UTC (releng/9.2, 9.2-RC1-p2) 2013-09-10 10:08:20 UTC (releng/9.2, 9.2-RC2-p2) CVE Name: CVE-2013-5666 For general information regarding FreeBSD Security Advisories, including descriptions of the fields above, security branches, and the following sections, please visit <URL:http://security.FreeBSD.org/>. I. Background The sendfile(2) system call allows a server application (such as an HTTP or FTP server) to transmit the contents of a file over a network connection without first copying it to application memory. High performance servers such as Apache and ftpd use sendfile. II. Problem Description On affected systems, if the length passed to sendfile(2) is non-zero and greater than the length of the file being transmitted, sendfile(2) will pad the transmission up to the requested length or the next pagesize boundary, whichever is smaller. The content of the additional bytes transmitted in this manner depends on the underlying filesystem, but may potentially include information useful to an attacker. III. Impact An unprivileged user with the ability to run arbitrary code may be able to obtain arbitrary kernel memory contents. 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. 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. [FreeBSD 9.2-STABLE] # fetch http://security.FreeBSD.org/patches/SA-13:11/sendfile-9.2-stable.patch # fetch http://security.FreeBSD.org/patches/SA-13:11/sendfile-9.2-stable.patch.asc # gpg --verify sendfile-9.2-stable.patch.asc [FreeBSD 9.2-RC1 and 9.2-RC2] # fetch http://security.FreeBSD.org/patches/SA-13:11/sendfile-9.2-rc.patch # fetch http://security.FreeBSD.org/patches/SA-13:11/sendfile-9.2-rc.patch.asc # gpg --verify sendfile-9.2-rc.patch.asc b) Apply the patch. # cd /usr/src # patch < /path/to/patch c) Recompile your kernel as described in <URL:http://www.FreeBSD.org/handbook/kernelconfig.html> and reboot the system. 3) 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 VI. Correction details The following list contains the correction revision numbers for each affected branch. Branch/path Revision - - ------------------------------------------------------------------------- stable/9/ r255443 releng/9.2/ r255444 - - ------------------------------------------------------------------------- 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:http://svnweb.freebsd.org/base?view=revision&revision=NNNNNN> VII. References <URL:http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2013-5666> The latest revision of this advisory is available at <URL:http://security.FreeBSD.org/advisories/FreeBSD-SA-13:11.sendfile.asc> - -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.14 (FreeBSD) iEYEARECAAYFAlIu8rIACgkQFdaIBMps37K01ACgmwaW3PZhjDqWSlTHusjIPNVy A/YAn3DFUAvlX8sH89taM+sedjbD5In8 =gZwu - -----END PGP SIGNATURE----- - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to firstname.lastname@example.org and we will forward your request to the appropriate person. NOTE: Third Party Rights This security bulletin is provided as a service to AusCERT's members. 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