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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2020.2337 IPv6 socket option race condition and use after free 9 July 2020 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: ipv6 Publisher: FreeBSD Operating System: FreeBSD Impact/Access: Increased Privileges -- Existing Account Execute Arbitrary Code/Commands -- Existing Account Resolution: Patch/Upgrade CVE Names: CVE-2020-7457 Original Bulletin: https://security.freebsd.org/advisories/FreeBSD-SA-20:20.ipv6.asc - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 ============================================================================= FreeBSD-SA-20:20.ipv6 Security Advisory The FreeBSD Project Topic: IPv6 socket option race condition and use after free Category: core Module: network Announced: 2020-07-08 Credits: syzkaller, Andy Nguyen Affects: All supported versions of FreeBSD. Corrected: 2020-04-02 15:30:51 UTC (stable/12, 12.1-STABLE) 2020-07-08 20:11:40 UTC (releng/12.1, 12.1-RELEASE-p7) 2020-07-06 20:23:14 UTC (stable/11, 11.4-STABLE) 2020-07-08 20:11:40 UTC (releng/11.4, 11.4-RELEASE-p1) 2020-07-08 20:11:40 UTC (releng/11.3, 11.3-RELEASE-p11) CVE Name: CVE-2020-7457 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 The IPV6_2292PKTOPTIONS socket option allows user code to set IPv6 header options on a socket. II. Problem Description The IPV6_2292PKTOPTIONS set handler was missing synchronization, so racing accesses could modify freed memory. III. Impact A malicious user application could trigger memory corruption, leading to privilege escalation. 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. Perform one of the following: 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 +10min "Rebooting for a 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-20:20/ipv6.patch # fetch https://security.FreeBSD.org/patches/SA-20:20/ipv6.patch.asc # gpg --verify ipv6.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/ r359565 releng/12.1/ r363026 stable/11/ r362975 releng/11.4/ r363026 releng/11.3/ r363026 - - ------------------------------------------------------------------------- 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://hackerone.com/reports/826026> <URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-7457> The latest revision of this advisory is available at <URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-20:20.ipv6.asc> - -----BEGIN PGP SIGNATURE----- iQKTBAEBCgB9FiEE/A6HiuWv54gCjWNV05eS9J6n5cIFAl8GLvVfFIAAAAAALgAo aXNzdWVyLWZwckBub3RhdGlvbnMub3BlbnBncC5maWZ0aGhvcnNlbWFuLm5ldEZD MEU4NzhBRTVBRkU3ODgwMjhENjM1NUQzOTc5MkY0OUVBN0U1QzIACgkQ05eS9J6n 5cJqxA/9H58yyRUSUy6BTRw0XkCQFO3r0NpTYPWK4RJFPWO2Jh5zL2QjxuSj3k9t zgJXM6a1RRgOxevxSzJJXD74BZz3XLJnC9T0tXsp3nikMrd+NSVN0g2jfAbx0l7R RFRUJOI2EfcGkIe0tZy4/nGr+H9eZiJt9a9vJ8DCoJuU9Ph/7w3GrVG+gbJfH4sV KhvhrRzla4ePadnHyQZALL5ov554BUa3dB9STz8zbdjt5yFREpvCJ9mIOHKNPBCR X5v7OMwhw++2Q0JtoMsmBHMi8zOkDpbjPk5eQNLHg3Iw9ZQrxW8KtM9Ru3KFtPw9 gisI9e53NkCUGLm9iq3oQG6CnCMulTMAlgN5f0HflEwy3vd7R/ibNLvx2yObmVOU cX1Nf0ydFfhoS/YQwArdGTUg12BlYL9lqiXTqojUBG+yikwA3XAIUJccpcYyZDLQ jR5N8Ct7fV9Ec5pdu4xkSQhKsto9pQVfS0Kabv7hlwumynVL+S7qsmS7FT3IC/4n FiXisrJr5TTNO8p/bIs8qooHYUkd06A5O8xy+gRDDPbgvYfevGWrd/vaHmiXpUsv dvv9ZnU8xlaSi66AEPs9kYw/WhF55deqaU1M0p6Ob3+TGyJIR3j3IPTAIIXSgTrq YiyvzqXM+ob3aysILYRv48LK7+5N/3hDU48FLUN6q1V99G7TV8o= =JUip - -----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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