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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2018.1423 Mishandling of x86 debug exceptions patched in FreeBSD 9 May 2018 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: kernel Publisher: FreeBSD Operating System: FreeBSD Impact/Access: Root Compromise -- Existing Account Execute Arbitrary Code/Commands -- Existing Account Access Privileged Data -- Existing Account Denial of Service -- Existing Account Resolution: Patch/Upgrade CVE Names: CVE-2018-8897 Reference: ASB-2018.0107 ESB-2018.1412 ESB-2018.1407 Original Bulletin: https://security.freebsd.org/advisories/FreeBSD-SA-18:06.debugreg.asc - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 ============================================================================= FreeBSD-SA-18:06.debugreg Security Advisory The FreeBSD Project Topic: Mishandling of x86 debug exceptions Category: core Module: kernel Announced: 2018-05-08 Credits: Nick Peterson, Everdox Tech LLC https://www.linkedin.com/in/everdox Andy Lutomirski Affects: All supported versions of FreeBSD. Corrected: 2018-05-08 17:03:33 UTC (stable/11, 11.2-PRERELEASE) 2018-05-08 17:12:10 UTC (releng/11.1, 11.1-RELEASE-p10) 2018-05-08 17:05:39 UTC (stable/10, 10.4-STABLE) 2018-05-08 17:12:10 UTC (releng/10.4, 10.4-RELEASE-p9) CVE Name: CVE-2018-8897 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 On x86 architecture systems, the stack is represented by the combination of a stack segment and a stack pointer, which must remain in sync for proper operation. Instructions related to manipulating the stack segment have special handling to facilitate consistency with changes to the stack pointer. II. Problem Description The MOV SS and POP SS instructions inhibit debug exceptions until the instruction boundary following the next instruction. If that instruction is a system call or similar instruction that transfers control to the operating system, the debug exception will be handled in the kernel context instead of the user context. III. Impact An authenticated local attacker may be able to read sensitive data in kernel memory, control low-level operating system functions, or may panic the system. 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, using either a binary or source code patch, and then 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 And reboot. 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 11.1] # fetch https://security.FreeBSD.org/patches/SA-18:06/debugreg.11.1.patch # fetch https://security.FreeBSD.org/patches/SA-18:06/debugreg.11.1.patch.asc # gpg --verify debugreg.11.1.patch.asc [FreeBSD 10.4] # fetch https://security.FreeBSD.org/patches/SA-18:06/debugreg.10.4.patch # fetch https://security.FreeBSD.org/patches/SA-18:06/debugreg.10.4.patch.asc # gpg --verify debugreg.10.4.patch.asc b) Apply the patch. Execute the following commands as root: # cd /usr/src # patch < /path/to/patch c) Recompile and install 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/ r333370 releng/10.4/ r333371 stable/11/ r333369 releng/11.1/ r333371 - - ------------------------------------------------------------------------- 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-2018-8897> The latest revision of this advisory is available at <URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-18:06.debugreg.asc> - -----BEGIN PGP SIGNATURE----- iQKTBAEBCgB9FiEE/A6HiuWv54gCjWNV05eS9J6n5cIFAlrx3HhfFIAAAAAALgAo aXNzdWVyLWZwckBub3RhdGlvbnMub3BlbnBncC5maWZ0aGhvcnNlbWFuLm5ldEZD MEU4NzhBRTVBRkU3ODgwMjhENjM1NUQzOTc5MkY0OUVBN0U1QzIACgkQ05eS9J6n 5cK/jhAAmPPCFZRMvbyG0VBCBqo5COFZ/32IMOWFDGMlsSi+CEgcGM51SzYZi97c zsT/2RgMsvBdggk41wvXqp1gKxgIbJe22af7l+D18e6rDEesueJqSiizcHmfGQul X+ZRUkFxTkCNz0Ajp4clqbavuHNiCmiKmH/0X8LMk31SXIVE3oH0Pphf0W8qJqxz 4k2nvc6NoPWEMVA0rsj3n6sB0NhvV1ddLLmGpoDgedSyz77PCDgWGMoh5ny5sY12 tHNB1r+gL624Y0l8xoyVJP0Snk0emzeQQ5HOTa8DRIwD/a0Uxy+xKcvDMorW9U6M zsxrMs9EwSJYpwLxsQ/YVTgFvyQbkHXFXg56hxqUvnnEEahGfF47d/9x2lyzDr8r H+ncl9a+PfOCJ5OcwkjzorQv+Pq65JFlc15bxLS+zyU4g6yJDnHdk7Azbc60Uwq/ chauKmosm1I1CVH60JG00rmvoiX7b5ZRdEGEzAFt4XIX+EuXPnI84C5DxiD1YG+3 n7IygNZNGtGfIrNhWEn2VK+VGzFEm2p4RkreWbGwrWQIxfd5gOJxvjAPSwjgy5rl dwRW7bMzowIGnrlzCF18Qc2xnFD31JPYDdsI+Fa8d1YkCVWRZ79VX57Locw50/de c5nZRJGk4AQ1lXxkNTkxWnstfb/q8fBVPkIEQKVHpVnGiI/pQpQ= =Oyxs - -----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). On call after hours for member emergencies only. =========================================================================== -----BEGIN PGP SIGNATURE----- Comment: http://www.auscert.org.au/render.html?it=1967 iQIVAwUBWvKTZ4x+lLeg9Ub1AQgORw/5ATUxDRLgGi83xPrKsAVBHQPUR78wr2LV zBSespxc94l6Z3Dq4ShCvmVaHgKkP4JnDSt2EObW+t1uNr4KaWRJKrhmb21JlnF+ b0bkp9raaqkom4PYD60lcE+HjXwZ8ECzUs+ZZZYa/oPbIKdkQw/v5T2dQFukBycn O0aKPFBn9al9mKbP83KOLUWBZJqBqx975eMVAf8RX9SXGZYnGUMF8AsDK82oWVJ0 JbMPjqQpswHA7p2o2hES+ckobTtUCxcAJdOUEBFCTnAYbdonj0N9XEzAbE499ZZn Kz1iE90g6Z0uOzIIcyJZDoLWUvNlkEXfqK8ZvNa8g4PZQFX8Ejq5vgw25Sxk+rc7 IwbxsGZgBGgc+GSJkSuGneUqfpaUyU2O1ZaJOSGCyyCNB33v7y8ZDg6AzpBuMA+u yJd/GamMOXvOrloNq15DQTnpF+iM3+WHg0na2BqK+edsDMTH/CByYgt58zkEa/LS SCMupoQNrGMqP6Kap78rsT6frtrj66qc9mj9bXoiEbp8dvg1YaKHjYYQOZc+k8zB mi4idYufYYXpb6xQS8qZ852BMhcFPU911lkA+Dy9m5ZSz1t5eLFc80DEuBOF/swO AQ3gIt1mqXNl1mstovlZdMI+KxvdtqMmWXODJ7hTZ72cE5bIs6IQO+56QfP9J7Xh aahcIelhA20= =Ngu/ -----END PGP SIGNATURE-----