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[ GLSA 200407-12 ] Linux Kernel: Remote DoS vulnerability with IPTables TCP Handling
From: Tim Yamin <plasmaroo () gentoo org>
Date: Wed, 14 Jul 2004 22:04:06 +0100
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Gentoo Linux Security Advisory GLSA 200407-12 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - http://security.gentoo.org/ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Severity: High Title: Linux Kernel: Remote DoS vulnerability with IPTables TCP Handling Date: July 14, 2004 Bugs: #55694 ID: 200407-12 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Synopsis ======== A flaw has been discovered in 2.6 series Linux kernels that allows an attacker to send a malformed TCP packet, causing the affected kernel to possibly enter an infinite loop and hang the vulnerable machine. Background ========== The Linux kernel is responsible for managing the core aspects of a GNU/Linux system, providing an interface for core system applications as well as providing the essential structure and capability to access hardware that is needed for a running system. Affected packages ================= ------------------------------------------------------------------- Kernel / Unaffected / Remerge ------------------------------------------------------------------- 1 aa-sources ............... >= 2.6.5-r5 ...................... YES 2 ck-sources ............... >= 2.6.7-r2 ...................... YES 3 gentoo-dev-sources ....... >= 2.6.7-r7 .......................... 4 hardened-dev-sources ..... >= 2.6.7-r1 .......................... 5 hppa-dev-sources ....... >= 2.6.7_p1-r1 ......................... 6 mips-sources ............ *>= 2.6.4-r4 .......................... .......................... >= 2.6.7-r1 .......................... 7 mm-sources ............... >= 2.6.7-r4 ...................... YES 8 pegasos-dev-sources ...... >= 2.6.7-r1 .......................... 9 rsbac-dev-sources ........ >= 2.6.7-r1 .......................... 10 uclinux-sources ........ >= 2.6.7_p0-r1 ......................... 11 usermode-sources ......... >= 2.6.6-r2 .......................... 12 win4lin-sources .......... >= 2.6.7-r1 .......................... 13 xbox-sources ............. >= 2.6.7-r1 .......................... 14 development-sources ...... Vulnerable! .......................... ------------------------------------------------------------------- NOTE: Some kernels are still vulnerable. Users should migrate to another kernel if one is available or seek another solution such as patching their existing kernel. ------------------------------------------------------------------- NOTE: Packages marked with "Remerge" as "YES" require a re-merge even though Portage does not indicate a newer version! ------------------------------------------------------------------- 14 affected packages on all of their supported architectures. ------------------------------------------------------------------- Description =========== An attacker can utilize an erroneous data type in the IPTables TCP option handling code, which lies in an iterator. By making a TCP packet with a header length larger than 127 bytes, a negative integer would be implied in the iterator. Impact ====== By sending one malformed packet, the kernel could get stuck in a loop, consuming all of the CPU resources and rendering the machine useless, causing a Denial of Service. This vulnerability requires no local access. Workaround ========== If users do not use the netfilter functionality or do not use any ``--tcp-option'' rules they are not vulnerable to this exploit. Users that are may remove netfilter support from their kernel or may remove any ``--tcp-option'' rules they might be using. However, all users are urged to upgrade their kernels to patched versions. Resolution ========== Users are encouraged to upgrade to the latest available sources for their system: # emerge sync # emerge -pv your-favorite-sources # emerge your-favorite-sources # # Follow usual procedure for compiling and installing a kernel. # # If you use genkernel, run genkernel as you would do normally. Availability ============ This GLSA and any updates to it are available for viewing at the Gentoo Security Website: http://security.gentoo.org/glsa/glsa-200407-12.xml Concerns? ========= Security is a primary focus of Gentoo Linux and ensuring the confidentiality and security of our users machines is of utmost importance to us. Any security concerns should be addressed to security () gentoo org or alternatively, you may file a bug at http://bugs.gentoo.org. License ======= Copyright 2004 Gentoo Foundation, Inc; referenced text belongs to its owner(s). The contents of this document are licensed under the Creative Commons - Attribution / Share Alike license. http://creativecommons.org/licenses/by-sa/1.0
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- [ GLSA 200407-12 ] Linux Kernel: Remote DoS vulnerability with IPTables TCP Handling Tim Yamin (Jul 16)