Return-Path: Delivered-To: hvjuan@kanux.com Received: (qmail 10594 invoked from network); 1 Jul 2004 13:34:31 -0000 Received: from mail.secunia.com (213.150.41.240) by 192.168.74.2 with SMTP; 1 Jul 2004 13:34:31 -0000 Received: (qmail 4145 invoked from network); 1 Jul 2004 13:13:41 -0000 Received: from unknown (HELO secunia.com) (192.168.100.228) by mail.secunia.com with SMTP; 1 Jul 2004 13:13:41 -0000 Received: (from nobody@localhost) by secunia.com (8.12.10/8.12.10/Submit) id i61DHRf1020304; Thu, 1 Jul 2004 15:17:27 +0200 Date: Thu, 1 Jul 2004 15:17:27 +0200 Message-Id: <200407011317.i61DHRf1020304@secunia.com> To: hvjuan@kanux.com Subject: [SA11980] Linux Kernel Netfilter TCP Option Matching Denial of Service Vulnerability From: Secunia Security Advisories Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit TITLE: Linux Kernel Netfilter TCP Option Matching Denial of Service Vulnerability SECUNIA ADVISORY ID: SA11980 VERIFY ADVISORY: http://secunia.com/advisories/11980/ CRITICAL: Moderately critical IMPACT: DoS WHERE: From remote OPERATING SYSTEM: Linux Kernel 2.6.x http://secunia.com/product/2719/ DESCRIPTION: Adam Osuchowski and Tomasz Dubinski have reported a vulnerability in the Linux kernel, which can be exploited by malicious people to cause a DoS (Denial of Service). The vulnerability is caused due to the use of an incorrect variable type within the "tcp_find_option()" function of the netfilter subsystem. This can be exploited by sending a specially crafted TCP packet, which causes the kernel to enter an infinite loop and consume all available CPU resources. Successful exploitation requires that iptables is used with rules matching TCP options ("--tcp-option"). SOLUTION: Don't use any rules matching TCP options. PROVIDED AND/OR DISCOVERED BY: Adam Osuchowski and Tomasz Dubinski ---------------------------------------------------------------------- About: This Advisory was delivered by Secunia as a free service to help everybody keeping their systems up to date against the latest vulnerabilities. Subscribe: http://secunia.com/secunia_security_advisories/ Definitions: (Criticality, Where etc.) http://secunia.com/about_secunia_advisories/ Please Note: Secunia recommends that you verify all advisories you receive by clicking the link. Secunia NEVER sends attached files with advisories. Secunia does not advise people to install third party patches, only use those supplied by the vendor. ---------------------------------------------------------------------- Unsubscribe: Secunia Security Advisories http://secunia.com/sec_adv_unsubscribe/?email=hvjuan@kanux.com ----------------------------------------------------------------------