So, who's going to be brave and upgrade first and share their experience? ;-)
-- Chris Scott Host Orlando, Inc http://www.hostorlando.com/ -------- Original Message -------- Subject: [Full-Disclosure] FreeBSD Security Advisory FreeBSD-SA-04:04.tcp Date: Tue, 2 Mar 2004 11:55:44 -0800 (PST) From: FreeBSD Security Advisories <[EMAIL PROTECTED]> Reply-To: [EMAIL PROTECTED] To: FreeBSD Security Advisories <[EMAIL PROTECTED]> -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 ============================================================================= FreeBSD-SA-04:04.tcp Security Advisory The FreeBSD Project Topic: many out-of-sequence TCP packets denial-of-service Category: core Module: kernel Announced: 2004-03-02 Credits: iDEFENSE Affects: All FreeBSD releases Corrected: 2004-03-02 17:19:18 UTC (RELENG_4) 2004-03-02 17:24:46 UTC (RELENG_5_2, 5.2.1-RELEASE-p1) 2004-03-02 17:26:33 UTC (RELENG_4_9, 4.9-RELEASE-p3) 2004-03-02 17:27:47 UTC (RELENG_4_8, 4.8-RELEASE-p16) CVE Name: CAN-2004-0171 FreeBSD only: NO 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 does not limit the number of TCP segments that may be held in a reassembly queue. III. Impact A remote attacker may conduct a low-bandwidth denial-of-service attack against a machine providing services based on TCP (there are many such services, including HTTP, SMTP, and FTP). By sending many out-of-sequence TCP segments, the attacker can cause the target machine to consume all available memory buffers (``mbufs''), likely leading to a system crash. IV. Workaround It may be possible to mitigate some denial-of-service attacks by implementing timeouts at the application level. V. Solution Do one of the following: 1) Upgrade your vulnerable system to 4-STABLE, or to the RELENG_5_2, RELENG_4_9, or RELENG_4_8 security branch dated after the correction date. OR 2) Patch your present system: The following patch has been verified to apply to FreeBSD 4.x and 5.x systems. a) Download the relevant patch from the location below, and verify the detached PGP signature using your PGP utility. [FreeBSD 5.2] # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-04:04/tcp52.patch # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-04:04/tcp52.patch.asc [FreeBSD 4.8, 4.9] # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-04:04/tcp47.patch # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-04:04/tcp47.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. VI. Correction details The following list contains the revision numbers of each file that was corrected in FreeBSD. Branch Revision Path - ------------------------------------------------------------------------- RELENG_4 src/UPDATING 1.73.2.90 src/sys/conf/newvers.sh 1.44.2.33 src/sys/netinet/tcp_input.c 1.107.2.40 src/sys/netinet/tcp_subr.c 1.73.2.33 src/sys/netinet/tcp_var.h 1.56.2.15 RELENG_5_2 src/UPDATING 1.282.2.9 src/sys/conf/newvers.sh 1.56.2.8 src/sys/netinet/tcp_input.c 1.217.2.2 src/sys/netinet/tcp_subr.c 1.169.2.4 src/sys/netinet/tcp_var.h 1.93.2.2 RELENG_4_9 src/UPDATING 1.73.2.89.2.4 src/sys/conf/newvers.sh 1.44.2.32.2.4 src/sys/netinet/tcp_input.c 1.107.2.38.2.1 src/sys/netinet/tcp_subr.c 1.73.2.31.4.1 src/sys/netinet/tcp_var.h 1.56.2.13.4.1 RELENG_4_8 src/UPDATING 1.73.2.80.2.19 src/sys/conf/newvers.sh 1.44.2.29.2.17 src/sys/netinet/tcp_input.c 1.107.2.37.2.1 src/sys/netinet/tcp_subr.c 1.73.2.31.2.1 src/sys/netinet/tcp_var.h 1.56.2.13.2.1 - ------------------------------------------------------------------------- VII. References <URL:http://www.idefense.com/application/poi/display?id=78&type=vulnerabilities> -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.4 iD8DBQFAROKHFdaIBMps37IRAu9EAJ9VY70IDYdjr6GkKJCJCGyvBV3OcQCeIXwL UDTQ4rcO/SP2rFRZ0Mcj1iQ= =Gkct -----END PGP SIGNATURE----- _______________________________________________ [EMAIL PROTECTED] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-security-notifications To unsubscribe, send any mail to "[EMAIL PROTECTED]" _______________________________________________ Full-Disclosure - We believe in it. Charter: http://lists.netsys.com/full-disclosure-charter.html
