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freebsd_advisoryFreeBSD OrgFREEBSD_ADVISORY:FREEBSD-SA-18:06.DEBUGREG
HistoryMay 08, 2018 - 12:00 a.m.

FreeBSD-SA-18:06.debugreg

2018-05-0800:00:00
FreeBSD Org
www.freebsd.org

CVSS2

7.2

Attack Vector

LOCAL

Attack Complexity

LOW

Authentication

NONE

Confidentiality Impact

COMPLETE

Integrity Impact

COMPLETE

Availability Impact

COMPLETE

AV:L/AC:L/Au:N/C:C/I:C/A:C

CVSS3

7.8

Attack Vector

LOCAL

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS

0.001

Percentile

31.1%

-----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 . 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 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: VII. References The latest revision of this advisory is available at -----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-----

CVSS2

7.2

Attack Vector

LOCAL

Attack Complexity

LOW

Authentication

NONE

Confidentiality Impact

COMPLETE

Integrity Impact

COMPLETE

Availability Impact

COMPLETE

AV:L/AC:L/Au:N/C:C/I:C/A:C

CVSS3

7.8

Attack Vector

LOCAL

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS

0.001

Percentile

31.1%