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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2018.2754 FreeBSD-SA-18:12.elf: Improper ELF header parsing 14 September 2018 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: FreeBSD kernel Publisher: FreeBSD Operating System: FreeBSD Impact/Access: Denial of Service -- Existing Account Access Privileged Data -- Existing Account Resolution: Patch/Upgrade CVE Names: CVE-2018-6924 Original Bulletin: https://www.freebsd.org/security/advisories/FreeBSD-SA-18:12.elf.asc - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 ============================================================================= FreeBSD-SA-18:12.elf Security Advisory The FreeBSD Project Topic: Improper ELF header parsing Category: core Module: kernel Announced: 2018-09-12 Credits: Thomas Barabosch, Fraunhofer FKIE; Mark Johnston Affects: All supported versions of FreeBSD. Corrected: 2018-09-12 05:02:11 UTC (stable/11, 11.1-STABLE) 2018-09-12 05:07:35 UTC (releng/11.2, 11.2-RELEASE-p3) 2018-09-12 05:07:35 UTC (releng/11.1, 11.1-RELEASE-p14) 2018-09-12 05:03:30 UTC (stable/10, 10.4-STABLE) 2018-09-12 05:07:35 UTC (releng/10.4, 10.4-RELEASE-p12) CVE Name: CVE-2018-6924 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 To execute a binary the kernel must parse the ELF header to determine the entry point address, the program interpreter, and other parameters. II. Problem Description Insufficient validation was performed in the ELF header parser, and malformed or otherwise invalid ELF binaries were not rejected as they should be. III. Impact Execution of a malicious ELF binary may result in a kernel crash or may disclose kernel memory. IV. Workaround No workaround is available. V. Solution Upgrade your vulnerable system to a supported FreeBSD stable or release / security branch (releng) dated after the correction date, and reboot. 1) 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 # shutdown -r +30 "Rebooting for 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-18:12/elf.patch # fetch https://security.FreeBSD.org/patches/SA-18:12/elf.patch.asc # gpg --verify elf.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 The following list contains the correction revision numbers for each affected branch. Branch/path Revision - - ------------------------------------------------------------------------- stable/10/ r338605 releng/10.4/ r338606 stable/11/ r338604 releng/11.1/ r338606 releng/11.2/ r338606 - - ------------------------------------------------------------------------- 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-2018-6924> The latest revision of this advisory is available at <URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-18:12.elf.asc> - -----BEGIN PGP SIGNATURE----- iQKTBAEBCgB9FiEE/A6HiuWv54gCjWNV05eS9J6n5cIFAluYoK9fFIAAAAAALgAo aXNzdWVyLWZwckBub3RhdGlvbnMub3BlbnBncC5maWZ0aGhvcnNlbWFuLm5ldEZD MEU4NzhBRTVBRkU3ODgwMjhENjM1NUQzOTc5MkY0OUVBN0U1QzIACgkQ05eS9J6n 5cKA+BAApeUtPHpy5mEHC8ftJ+3NZpfI8gcfuPE0dlJi6CpXq8/ruXN5Yt5X0E0l hlbNGqEMckfe3F81rCXLbtu0zeAnSBfAFcm9xSBa6aSRfP4GAZtKDKwilPqqT9F8 sOrPR/mAfxWmWcfDt8ggAx6akr2Tt48t7TiBP/kA14+CzVmp/pMU/ceFDLk8JYjY PQzVM4fHC5xeBWtA2JjMNHnhR6XMeiDOLkgeRiRW1LhB/OwWwcb0uzVixxR34mCT vFm1eJteAitoVclgnI//GkzZZ6b7SZkqyqODWKVLWXaYgb8/Z6SaKAQm2TWuHPEh nzIpPGhnXZc+36Nn9/HYDKVn3skD1sYAnTMgPcUYZH3KfkohvFdHlnoGqkcnMwTy mSKkQx9ojuLfwot7tyJCbgU/6e82ed1g9EiFZXwW8x4ePClaAvrDozz0QGwlXgyY 1jBbFp/gYznhxTetVRHo5ug5SHZgD2Ye46TCoglHX0CprhkWwpKenoCEyfyjlHXH uI+RPd46TlQfuK4bqURRpWvNWprXGqQ0ypFVW2JJgqLPBX0QS79gzqO++C8tRqQv e16mqzBGNIre/8FOCBpV/Z61NgxqeYo2ndHxc9VTMiFXK/2v3TDK9AvYZ1/xEvwC IRpC+qo870B5XT/ihC/KpYI4jgM2/pK/Mdez6Q4s5M6eeCBHAgw= =J/a5 - -----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 auscert@auscert.org.au 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. As AusCERT did not write the document quoted above, AusCERT has had no control over its content. The decision to follow or act on information or advice contained in this security bulletin is the responsibility of each user or organisation, and should be considered in accordance with your organisation's site policies and procedures. AusCERT takes no responsibility for consequences which may arise from following or acting on information or advice contained in this security bulletin. NOTE: This is only the original release of the security bulletin. 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: https://www.auscert.org.au/bulletins/ =========================================================================== 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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