FreeBSD Errata Notice FreeBSD-EN-20:19.audit
1 December, 2020 by firstname.lastname@example.org | freebsd
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 ============================================================================= FreeBSD-EN-20:19.audit Errata Notice The FreeBSD Project Topic: execve/fexecve system call auditing Category: core Module: kernel Announced: 2020-12-01 Affects: FreeBSD 12.1 and later. Corrected: 2020-10-27 13:13:04 UTC (stable/12, 12.2-STABLE) 2020-12-01 19:34:45 UTC (releng/12.2, 12.2-RELEASE-p1) 2020-12-01 19:34:45 UTC (releng/12.1, 12.1-RELEASE-p11) For general information regarding FreeBSD Errata Notices and Security Advisories, including descriptions of the fields above, security branches, and the following sections, please visit <URL:https://security.FreeBSD.org/>. I. Background The audit(4) facility allows a system administrator to audit security-relevant events. System calls are one such security-related event, and the audit(4) facility will record whether the system call was successful along with other important details. II. Problem Description All execve/fexecve system calls in affected versions will be reported as a failure, even upon successful execution. For affected kernels, the exact error reported is EJUSTRETURN, 201, or "Just return" depending on the tooling used. These can safely be considered successful returns for the fexecve and execve system calls. Note that audit trails that were produced by kernels starting with FreeBSD 12.0 will exhibit this problem. III. Impact It is important to be able to determine when a process is, for instance, executing a shell. Such events may be indicative of an intrusion if they are not expected. Failure to report such an execution as successful may result in intrusions that are no longer detectable. IV. Workaround No workaround is available. This error is irrelevant for system administrators that do not use the audit(4) facility. Users of the audit(4) facility could detect the specific error that is being returned as success, but this may complicate auditing as all failures must be recorded. V. Solution Upgrade your system to a supported FreeBSD stable or release / security branch (releng) dated after the correction date and reboot. Perform one of the following: 1) To update your 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 +10min "Rebooting for errata update" 2) To update your 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 12.2] # fetch https://security.FreeBSD.org/patches/EN-20:19/audit.12.2.patch # fetch https://security.FreeBSD.org/patches/EN-20:19/audit.12.2.patch.asc # gpg --verify audit.12.2.patch.asc [FreeBSD 12.1] # fetch https://security.FreeBSD.org/patches/EN-20:19/audit.12.1.patch # fetch https://security.FreeBSD.org/patches/EN-20:19/audit.12.1.patch.asc # gpg --verify audit.12.1.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/12/ r367080 releng/12.2/ r368249 releng/12.1/ r368249 - ------------------------------------------------------------------------- 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://bugs.freebsd.org/bugzilla/show_bug.cgi?id$9179> The latest revision of this advisory is available at <URL:https://security.FreeBSD.org/advisories/FreeBSD-EN-20:19.audit.asc> -----BEGIN PGP SIGNATURE----- iQKTBAEBCgB9FiEE/A6HiuWv54gCjWNV05eS9J6n5cIFAl/GnclfFIAAAAAALgAo aXNzdWVyLWZwckBub3RhdGlvbnMub3BlbnBncC5maWZ0aGhvcnNlbWFuLm5ldEZD MEU4NzhBRTVBRkU3ODgwMjhENjM1NUQzOTc5MkY0OUVBN0U1QzIACgkQ05eS9J6n 5cKqdBAAjBubNRAnzviekLybf9W6QnFT+9LrdoHEKM0epXT7GxHeGdKSbWwJPvaO PmogRZ88uPOvaRVYIjGLXjJf48zA6D5LuQrVre0BEICVsLEaKcoQpwqOgtSKroI4 LguI26tLC/TmzWMid7CUeDOxzY0yg+t8QWPvrc9kDCZVqDFjrWtUDurLYM50p8Rm FHfbWgFg0g3ytPF6k7DuafDrSJIs0lULwOtAPBrYR5chTr3/quc6onU99B6oxo4K rRe4Se458M3Gm637lADAqqyRXtzwMXZ+bJBRFjdMZb3gn6QSRphHluXosv9EWwZe FV5muyouYzxObkE4ev8dXF8Xx6LyuWfYLj5r064DRS7oFIZjIc/5F3wUITmkzCSc iqOPZ545JO2Mxd5JwgA6QMy1YagHJb4MKDpwoQG5EHdNSSIRxRy9SEnyyxB/boMw c65iw+SXM6ln+iAoFO9tyoLF5ek9OFRMH/1hemkY82eECcMA2m8/taSHb3++YOQr 7tmGjBZpynj/xDLQKwQiOrz5bVSPkWFc/4q9yQWAg/IoRPs+j/bsu1QoFlZX5b/8 /161dxwjs5ZLsTj+/oV/cBKQSWIFkSkbaK61ZAdrysXmGHB1jJ6OZDlsXK9kptHr XavfRbYVCs8tB6NmWWEcfRQvLso20u+9zLO2X0yGz0+XEpKNU4k=QTo/ -----END PGP SIGNATURE----- _______________________________________________ email@example.com mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-announce To unsubscribe, send any mail to "firstname.lastname@example.org"