[FreeBSD-Announce] FreeBSD Security Advisory FreeBSD-SA-14:08.tcp

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 ============================================================================= FreeBSD-SA-14:08.tcp Security Advisory The FreeBSD Project Topic: TCP reassembly vulnerability Category: core Module: inet Announced: 2014-04-30 Credits: Jonathan Looney Affects: All supported versions of FreeBSD. Corrected: 2014-04-30 04:04:20 UTC (stable/8, 8.4-STABLE) 2014-04-30 04:05:47 UTC (releng/8.4, 8.4-RELEASE-p9) 2014-04-30 04:05:47 UTC (releng/8.3, 8.3-RELEASE-p16) 2014-04-30 04:04:20 UTC (stable/9, 9.2-STABLE) 2014-04-30 04:05:47 UTC (releng/9.2, 9.2-RELEASE-p5) 2014-04-30 04:05:47 UTC (releng/9.1, 9.1-RELEASE-p12) 2014-04-30 04:03:05 UTC (stable/10, 10.0-STABLE) 2014-04-30 04:04:42 UTC (releng/10.0, 10.0-RELEASE-p2) CVE Name: CVE-2014-3000 For general information regarding FreeBSD Security Advisories, including descriptions of the fields above, security branches, and the following sections, please visit <URL:http://security.FreeBSD.org/>. I. Background The Transmission Control Protocol (TCP) of the TCP/IP protocol suite provides a connection-oriented, reliable, sequence-preserving data stream service. When network packets making up a TCP stream (``TCP segments'') are received out-of-sequence, they are maintained in a reassembly queue by the destination system until they can be re-ordered and re-assembled. II. Problem Description FreeBSD may add a reassemble queue entry on the stack into the segment list when the reassembly queue reaches its limit. The memory from the stack is undefined after the function returns. Subsequent iterations of the reassembly function will attempt to access this entry. III. Impact An attacker who can send a series of specifically crafted packets with a connection could cause a denial of service situation by causing the kernel to crash. Additionally, because the undefined on stack memory may be overwritten by other kernel threads, while extremely difficult, it may be possible for an attacker to construct a carefully crafted attack to obtain portion of kernel memory via a connected socket. This may result in the disclosure of sensitive information such as login credentials, etc. before or even without crashing the system. IV. Workaround It is possible to defend to these attacks by doing traffic normalization using a firewall. This can be done by including the following /etc/pf.conf configuration: scrub in all This requires pf(4) to be enabled, and have the mentioned configuration loaded. V. Solution Perform one of the following: 1) Upgrade your vulnerable system to a supported FreeBSD stable or release / security branch (releng) dated after the correction date. 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 http://security.FreeBSD.org/patches/SA-14:08/tcp.patch # fetch http://security.FreeBSD.org/patches/SA-14:08/tcp.patch.asc # gpg --verify tcp.patch.asc b) Apply the patch. # cd /usr/src # patch < /path/to/patch c) Recompile your kernel as described in <URL:http://www.FreeBSD.org/handbook/kernelconfig.html> and reboot the system. 3) 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 VI. Correction details The following list contains the correction revision numbers for each affected branch. Branch/path Revision - ------------------------------------------------------------------------- stable/8/ r265123 releng/8.3/ r265125 releng/8.4/ r265125 stable/9/ r265123 releng/9.1/ r265125 releng/9.2/ r265125 stable/10/ r265122 releng/10.0/ r265124 - ------------------------------------------------------------------------- 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:http://svnweb.freebsd.org/base?view=revision&revision=NNNNNN> VII. References <URL:http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-3000> The latest revision of this advisory is available at <URL:http://security.FreeBSD.org/advisories/FreeBSD-SA-14:08.tcp.asc> -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (FreeBSD) iQIcBAEBCgAGBQJTYHsHAAoJEO1n7NZdz2rngywP/joAE0afufOlFvOsSxeeXUWg kNhtEQV5iXgsbu8QPwM/ikmAgg2ONGLQ47A7w7vHF98qg8jk6W1aZCcRE5lIg8hg WP5boSFvzvTXIQCo8EsIdcbnNBEA6CrtVQOIvWtuow2z8T0MtSou78Ctq2SO0O+8 7lY9pFYguFBgUNmVC6jpChIGJS9uZtdz2Vn697B4fOyv1pn6wenW7teOsyN+4Dyj 7Wq/qppZDrYSnd+YdveUAFCyCoYIXcsLXbeeIVJC2g8x6LlDw8swZElZL6refX6L UPDBViI3ctAcjEgzAP1fN3d9FpA5oGJ67J9QcDxYIfTj5YrQiYoTs49ER9FD7k9Q UxrgLamZ45/D762/IpmLHCwD+FWdzhl9wufklUptrHNIyNyovwMxQDNnoGZUIKeZ x1fAfctXRAztISyQ5xqVw3nKLauPCSG6IniyyZ12BcFxmDvoEcyOFLqB1eN+l5DB aJvfiA4PjWIV1nVU+w4MKKAQbHQSgh9bu8EvYUuwNrGOtP49RV1HejWD85ePSgtr KOQ0HU8CGmTpWOMkDQBl8Ap1boP9iUOTRp/WuIxwMi+AqoKRuDrWs0sOAXIksu2s 0sgGnbI0lrg77lBW4FPvMaCg1dlzlfv4J9AExAh6Ur52qxh5GaOcI2NhYWbxvijh 5wgOBszZXV2kPRDAaJTa =uhXC -----END PGP SIGNATURE-----