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Cisco PPTP DoS Details?
From: Dragos Ruiu <dr () kyx net>
Date: Mon, 30 Jul 2001 01:03:59 -0700
Does anyone have any further details of this or any info sufficient to build a signature for this? Alerting on all pptp packets to your ciscos doesn't seem like the right thing to do.... thanks, --dr url: http://www.cisco.com/warp/public/707/PPTP-vulnerability-pub.html Cisco Security Advisory: Cisco IOS PPTP Vulnerability Revision 1.1 For Public Release 2001 July 12 08:00 (UTC -0800) Summary Point-to-Point Tunneling Protocol (PPTP) allows users to tunnel to an Internet Protocol (IP) network using a Point-to-Point Protocol (PPP). The protocol is described in RFC2637. PPTP implementation using Cisco IOSĀ® software releases contains a vulnerability that will crash a router if it receives a malformed or crafted PPTP packet. To expose this vulnerability, PPTP must be enabled on the router. PPTP is disabled by default. No additional special conditions are required. his vulnerability is present in all Cisco IOS releases that support PPTP. PPTP is supported in the following software releases: 12.1 train, releases: T, E, EZ, XM, XV, YA, YB, YD and YC 12.2 train, all releases No other Cisco product is vulnerable. There is no workaround for this vulnerability. This advisory is available at http://www.cisco.com/warp/public/707/PPTP-vulnerability-pub.html. Affected Products his vulnerability is present in all Cisco IOS releases that support PPTP. PPTP is supported in the following releases: 12.1 train, releases: T, E, EZ, XM, XV, YA, YB, YD and YC 12.2 train, all releases To determine if a Cisco product is running an affected IOS, log in to the device and issue the command show version. Look for the "Internetwork Operating System Software" or "IOS (tm)" information, which also will have a version number. Other Cisco devices either will not have the command show version or will give different output. Details By sending a crafted PPTP packet to port 1723, a control PPTP port, it is possible to crash the router. This vulnerability does not require special router configuration. Enabling PPTP is sufficient to expose the vulnerability. The router will crash after it receives a single packet. This vulnerability is documented as Cisco Bug ID CSCdt46181. Impact By repeatedly exploiting this vulnerability, it is possible to cause permanent Denial of Service (DoS). This denial is not only of the PPTP functionality but the whole router will stop functioning. Software Versions and Fixes Each row of the table describes a release train and the platforms or products for which it is intended. If a given release train is vulnerable, then the earliest possible releases that contain the fix and the anticipated date of availability for each are listed in the "Rebuild," "Interim," and "Maintenance" columns. A device running a release in the given train that is earlier than the release in a specific column (less than the earliest fixed release) is known to be vulnerable. The release should be upgraded at least to the indicated release or a later version (greater than the earliest fixed release label). When selecting a release, keep in mind the following definitions: Maintenance Most heavily tested and highly recommended release of any label in a given row of the table. Rebuild Constructed from the previous maintenance or major release in the same train, it contains the fix for a specific defect. Although it receives less testing, it contains only the minimal changes necessary to effect the repair. Interim Built at regular intervals between maintenance releases and receives less testing. Interims should be selected only if there is no other suitable release that addresses the vulnerability. Interim images should be upgraded to the next available maintenance release as soon as possible. Interim releases are not available via manufacturing, and usually they are not available for customer download from CCO without prior arrangement with the Cisco TAC. In all cases, customers should exercise caution to be certain the devices to be upgraded contain sufficient memory and that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, contact the Cisco TAC for assistance as shown in the following section. More information on Cisco IOS release names and abbreviations is available at http://www.cisco.com/warp/public/620/1.html. -- Dragos Ruiu <dr () dursec com> dursec.com ltd. / kyx.net - we're from the future gpg/pgp key on file at wwwkeys.pgp.net or at http://dursec.com/drkey.asc _______________________________________________ Snort-users mailing list Snort-users () lists sourceforge net Go to this URL to change user options or unsubscribe: http://lists.sourceforge.net/lists/listinfo/snort-users Snort-users list archive: http://www.geocrawler.com/redir-sf.php3?list=snort-users
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- Cisco PPTP DoS Details? Dragos Ruiu (Jul 30)