Cisco Security Advisory: Cisco IOS Misformed BGP Packet Causes Reload

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Cisco Security Advisory: Cisco IOS Misformed BGP Packet Causes Reload Revision 1.0 For Public Release 2005 January 26 1600 UTC (GMT) - ----------------------------------------------------------------------- Contents ======== Summary Affected Products Details Impact Software Versions and Fixes Obtaining Fixed Software Workarounds Exploitation and Public Announcements Status of This Notice: FINAL Distribution Revision History Cisco Security Procedures - ----------------------------------------------------------------------- Summary ======= A Cisco device running IOS� and enabled for the Border Gateway Protocol (BGP) is vulnerable to a Denial of Service (DoS) attack from a malformed BGP packet. Only devices with the command bgp log-neighbor-changes configured are vulnerable. The BGP protocol is not enabled by default, and must be configured in order to accept traffic from an explicitly defined peer. Unless the malicious traffic appears to be sourced from a configured, trusted peer, it would be difficult to inject a malformed packet. Cisco has made free software available to address this problem. This issue is tracked by CERT/CC VU#689326. This advisory will be posted at http://www.cisco.com/warp/public/707/cisco-sa-20050126-bgp.shtml. Affected Products ================= Vulnerable Products +------------------ This vulnerability is present in any unfixed version of Cisco IOS, from the beginning of support for the BGP protocol, including versions 9.x, 10.x, 11.x and 12.x. This issue affects all Cisco devices configured for BGP routing and running the bgp log-neighbor-changes command, which is on by default starting with releases 12.0(22)S, 12.0(11)ST, 12.1(10) E, 12.1(10) and later software. A router which is running the BGP process will have both a line in the configuration defining the AS number and the command bgp log-neighbor-changes, which can be seen by issuing the command show running-config: router bgp <AS number> bgp log-neighbor-changes To determine the software running on a Cisco product, log in to the device and issue the show version command to display the system banner. Cisco IOS software will identify itself as "Internetwork Operating System Software" or simply "IOS �." On the next line of output, the image name will be displayed between parentheses, followed by "Version" and the IOS release name. Other Cisco devices will not have the show version command or will give different output. The following example identifies a Cisco product running IOS release 12.0(3) with an installed image name of C2500-IS-L: Cisco Internetwork Operating System Software IOS (TM) 2500 Software (C2500-IS-L), Version 12.0(3), RELEASE SOFTWARE The release train label is "12.0." The next example shows a product running IOS release 12.0(2a)T1 with an image name of C2600-JS-MZ: Cisco Internetwork Operating System Software IOS (tm) C2600 Software (C2600-JS-MZ), Version 12.0(2a)T1, RELEASE SOFTWARE (fc1) Additional information about Cisco IOS release naming can be found at: http://www.cisco.com/warp/public/620/1.html. Products Confirmed Not Vulnerable +-------------------------------- Products confirmed not to be vulnerable include devices that do not run Cisco IOS, such as the Cisco Guard, products that cannot participate in BGP or products that cannot be configured for BGP. No other Cisco products are currently known to be affected by this vulnerability. Details ======= The Border Gateway Protocol (BGP) is a routing protocol defined by RFC 1771, and designed to manage IP routing in large networks. An affected Cisco device running a vulnerable version of Cisco IOS software with the BGP protocol enabled will reload if a malformed BGP packet is already queued on the interface when a BGP neighbor change is logged. The device is not vulnerable unless the command 'bgp log-neighbor-changes' is configured. Malformed packets may not come from malicious sources; a valid peering device such as another BGP speaking router which produces the specific malformed packet in error may trigger this behavior. BGP runs over the Transport Control Protocol (TCP), a reliable transport protocol which requires a valid three way handshake before any further messages will be accepted. The Cisco IOS implementation of BGP requires the explicit definition of a neighbor before a connection can be established, and traffic must appear to come from that neighbor. These implementation details make it very difficult to maliciously send a BGP packet to a Cisco IOS device from an unauthorized source. This bug may also be triggered by other means which are not considered remotely exploitable. The use of the commands 'show ip bgp neighbors' or 'debug ip bgp <neighbor> updates' can cause a router to reload if a router has previously queued a malformed packet. If there are no queued malformed packets, issuing these commands will have no harmful side effects. A Cisco device receiving an invalid BGP packet will reset and may take several minutes to become fully functional. This vulnerability may be exploited repeatedly resulting in an extended DoS attack. This issue is documented in bug ID CSCee67450. Impact ====== Successful exploitation of this vulnerability results in a reload of the device. Repeated exploitation could result in a sustained DoS attack. Software Versions and Fixes =========================== When considering software upgrades, please also consult http://www.cisco.com/en/US/products/products_security_advisories_listing.htm... and any subsequent advisories to determine exposure and a complete upgrade solution. 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 Technical Assistance Center ("TAC") for assistance. +----------------------------------------+ | Major | Availability of Repaired | | Release | Releases* | |------------+---------------------------| | Affected | | Maintenance | | 12.0-Based | Rebuild | Release | | Release | | | |------------+-------------+-------------| | 12.0 | 12.0(28b) | | |------------+-------------+-------------| | 12.0DA | Vulnerable; | | | | contact TAC | | |------------+-------------+-------------| | | Migrate to | | | 12.0DB | 12.3(4)T11 | | | | or later | | |------------+-------------+-------------| | | Migrate to | | | 12.0DC | 12.3(4)T11 | | | | or later | | |------------+-------------+-------------| | | 12.0(26)S5 | | | |-------------+-------------| | | 12.0(27)S4 | | |12.0S |-------------+-------------| | | 12.0(28)S1 | | | |-------------+-------------| | | | 12.0(29)S | |------------+-------------+-------------| | 12.0SC | Vulnerable; | | | | contact TAC | | |------------+-------------+-------------| | | Migrate to | | | 12.0SP | 12.0S or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.0ST | 12.0(26)S5 | | | | or later | | |------------+-------------+-------------| | 12.0SX | Vulnerable; | | | | contact TAC | | |------------+-------------+-------------| | | Migrate to | | | 12.0SY | 12.0(26)S5 | | | | or later | | |------------+-------------+-------------| | | Migrate to | | | 12.0SZ | 12.0(26)S5 | | | | or later | | |------------+-------------+-------------| | | Migrate to | | | 12.0T | 12.1 or | | | | later | | |------------+-------------+-------------| | | | 12.0(28)W5 | | 12.0W5 | | (31) | | | | | |------------+-------------+-------------| | 12.0WC | Not Vulnerable, no | | | support for BGP | |------------+-------------+-------------| | 12.0WT | Vulnerable; | | | | contact TAC | | |------------+-------------+-------------| | 12.0WX | Vulnerable; | | | | contact TAC | | |------------+-------------+-------------| | 12.0XA | Migrate to | | | | 12.1 latest | | |------------+-------------+-------------| | | Migrate to | | | 12.0XB | 12.1 or | | | | later | | |------------+-------------+-------------| | 12.0XC | Migrate to | | | | 12.1 latest | | |------------+-------------+-------------| | 12.0XD | Migrate to | | | | 12.1 latest | | |------------+-------------+-------------| | | Migrate to | | | 12.0XE | 12.1E | | | | latest | | |------------+-------------+-------------| | 12.0XF | Vulnerable; | | | | contact TAC | | |------------+-------------+-------------| | 12.0XG | Migrate to | | | | 12.1 latest | | |------------+-------------+-------------| | | Migrate to | | | 12.0XH | 12.1 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.0XI | 12.1 or | | | | later | | |------------+-------------+-------------| | 12.0XJ | Migrate to | | | | 12.1 latest | | |------------+-------------+-------------| | 12.0XK | Migrate to | | | | 12.2 latest | | |------------+-------------+-------------| | 12.0XL | Migrate to | | | | 12.2 latest | | |------------+-------------+-------------| | | Migrate to | | | 12.0XM | 12.1 or | | | | later | | |------------+-------------+-------------| | 12.0XN | Migrate to | | | | 12.1 latest | | |------------+-------------+-------------| | 12.0XP | Vulnerable; | | | | contact TAC | | |------------+-------------+-------------| | | Migrate to | | | 12.0XQ | 12.1 or | | | | later | | |------------+-------------+-------------| | 12.0XR | Migrate to | | | | 12.2 latest | | |------------+-------------+-------------| | | Migrate to | | | 12.0XS | 12.1E | | | | latest | | |------------+-------------+-------------| | 12.0XT | Vulnerable; | | | | contact TAC | | |------------+-------------+-------------| | 12.0XU | Vulnerable; | | | | contact TAC | | |------------+-------------+-------------| | | Migrate to | | | 12.0XV | 12.1 or | | | | later | | |------------+-------------+-------------| | Affected | | Maintenance | | 12.1-Based | Rebuild | Release | | Release | | | |------------+-------------+-------------| | 12.1 | | 12.1(26) | |------------+-------------+-------------| | 12.1AA | Migrate to | | | | 12.2 latest | | |------------+-------------+-------------| | 12.1AX | 12.1(14)AX3 | | |------------+-------------+-------------| | | Migrate to | | | 12.1AY | 12.1(22)EA2 | | | | or later | | |------------+-------------+-------------| | | Migrate to | | | 12.1AZ | 12.1(22)EA2 | | | | or later | | |------------+-------------+-------------| | 12.1DA | Vulnerable; | | | | contact TAC | | |------------+-------------+-------------| | | Migrate to | | | 12.1DB | 12.3(4)T11 | | | | or later | | |------------+-------------+-------------| | | Migrate to | | | 12.1DC | 12.3(4)T11 | | | | or later | | |------------+-------------+-------------| | | 12.1(22)E3 | | | |-------------+-------------| | 12.1E | 12.1(23)E2 | | | |-------------+-------------| | | | 12.1(26)E | |------------+-------------+-------------| | 12.1EA | 12.1(22)EA2 | | |------------+-------------+-------------| | 12.1EC | Vulnerable; | | | | contact TAC | | |------------+-------------+-------------| | 12.1EO | Vulnerable; | | | | contact TAC | | |------------+-------------+-------------| | | Migrate to | | | 12.1EV | 12.2S | | | | latest | | |------------+-------------+-------------| | | Migrate to | | | 12.1EW | 12.2(18)EW2 | | | | or later | | |------------+-------------+-------------| | | Migrate to | | | 12.1EX | 12.1E | | | | latest | | |------------+-------------+-------------| | | Migrate to | | | 12.1EY | 12.1E | | | | latest | | |------------+-------------+-------------| | | Migrate to | | | 12.1T | 12.2 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.1XA | 12.2 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.1XB | 12.2 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.1XC | 12.2 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.1XD | 12.2 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.1XE | 12.1E | | | | latest | | |------------+-------------+-------------| | | Migrate to | | | 12.1XF | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.1XG | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.1XH | 12.2 or | | | | later | | |------------+-------------+-------------| | 12.1XI | Migrate to | | | | 12.2 latest | | |------------+-------------+-------------| | | Migrate to | | | 12.1XJ | 12.3 or | | | | later | | |------------+-------------+-------------| | | MMigrate to | | | 12.1XL | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.1XM | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.1XP | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.1XQ | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.1XR | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.1XT | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.1XU | 12.3 or | | | | later | | |------------+-------------+-------------| | 12.1XV | Vulnerable; | | | | contact TAC | | |------------+-------------+-------------| | | Migrate to | | | 12.1YA | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.1YB | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.1YC | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.1YD | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.1YE | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.1YF | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.1YH | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.1YI | 12.2(2)YC | | | | or later | | |------------+-------------+-------------| | | Migrate to | | | 12.1YJ | 12.1(22)EA2 | | | | or later | | |------------+-------------+-------------| | Affected | Rebuild | Maintenance | | 12.2-Based | | Release | |------------+-------------+-------------| | 12.2 | | 12.2(27) | |------------+-------------+-------------| | | Migrate to | | | 12.2B | 12.3(4)T11 | | | | or later | | |------------+-------------+-------------| | 12.2BC | Vulnerable; | | | | contact TAC | | |------------+-------------+-------------| | | Migrate to | | | 12.2BW | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | | 12.3(7)XI3 | | | 12.2BX | -- | | | | Available 2 | | | | /15/05 | | |------------+-------------+-------------| | | Migrate to | | | 12.2BY | 12.3(4)T11 | | | | or later | | |------------+-------------+-------------| | | Migrate to | | | | 12.3(7)XI3 | | | 12.2BZ | -- | | | | Available 2 | | | | /15/05 | | |------------+-------------+-------------| | 12.2CZ | Vulnerable; | | | | contact TAC | | |------------+-------------+-------------| | 12.2DA | Vulnerable; | | | | contact TAC | | |------------+-------------+-------------| | | Migrate to | | | 12.2DD | 12.3(4)T11 | | | | or later | | |------------+-------------+-------------| | | Migrate to | | | 12.2DX | 12.3(4)T11 | | | | or later | | |------------+-------------+-------------| | | 12.2(18)EW2 | | |12.2EW |-------------+-------------| | | | 12.2(25)EW | |------------+-------------+-------------| | | | | |12.2JK |12.2(15)JK2 |-------------| | | | | |------------+-------------+-------------| | | Migrate to | | | 12.2MB | 12.2(25)SW | | | | or later | | |------------+-------------+-------------| | | Migrate to | | | 12.2MC | 12.3(11)T | | | | or later | | |------------+-------------+-------------| | | Migrate to | | | 12.2MX | 12.3(8)T5 | | | | or later | | |------------+-------------+-------------| | 12.2S | | 12.2(25)S | |------------+-------------+-------------| | 12.2SE | 12.2(20)SE3 | | |------------+-------------+-------------| | 12.2SU | 12.2(14)SU2 | | |------------+-------------+-------------| | 12.2SW | Migrate to | | | | 12.2(25)SW | | |------------+-------------+-------------| | | Migrate to | | | 12.2SX | 12.2(17d) | | | | SXB5 | | |------------+-------------+-------------| | | Migrate to | | | 12.2SXA | 12.2(17d) | | | | SXB5 | | |------------+-------------+-------------| | 12.2SXB | 12.2(17d) | | | | SXB5 | | |------------+-------------+-------------| | 12.2SXD | 12.2(18) | | | | SXD2 | | |------------+-------------+-------------| | | Migrate to | | | 12.2SY | 12.2(17d) | | | | SXB5 | | |------------+-------------+-------------| | | Migrate to | | | 12.2SZ | 12.2(25)S | | | | or later | | |------------+-------------+-------------| | | Migrate to | | | 12.2T | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2XA | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2XB | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2XC | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2XD | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2XE | 12.3 or | | | | later | | |------------+-------------+-------------| | 12.2XF | Vulnerable; | | | | contact TAC | | |------------+-------------+-------------| | | Migrate to | | | 12.2XG | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2XH | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2XI | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2XJ | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2XK | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2XL | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2XM | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2XN | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2XQ | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2XS | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2XT | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2XU | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2XW | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2XZ | 12.3 or | | | | later | | |------------+-------------+-------------| | 12.2YA | 12.2(4)YA8 | | |------------+-------------+-------------| | | Migrate to | | | 12.2YB | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2YC | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2YE | 12.2S or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2YF | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2YG | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2YH | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2YJ | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2YK | 12.3T or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2YL | 12.3T or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2YM | 12.3T or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2YN | 12.3T or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2YO | 12.2(17d) | | | | SXB5 | | |------------+-------------+-------------| | | Migrate to | | | 12.2YP | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2YQ | 12.3(4)T11 | | | | or later | | |------------+-------------+-------------| | | Migrate to | | | 12.2YR | 12.3(4)T11 | | | | or later | | |------------+-------------+-------------| | | Migrate to | | | 12.2YS | 12.3T or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2YT | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2YU | 12.3T or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2YV | 12.3(4)T11 | | | | or later | | |------------+-------------+-------------| | | Migrate to | | | 12.2YW | 12.3(4)T11 | | | | or later | | |------------+-------------+-------------| | | Migrate to | | | 12.2YX | 12.2(14)SU2 | | | | or later | | |------------+-------------+-------------| | | Migrate to | | | 12.2YY | 12.3T or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2YZ | 12.2(25)S | | | | or later | | |------------+-------------+-------------| | | Migrate to | | | 12.2ZA | 12.2(25)S | | | | or later | | |------------+-------------+-------------| | | Migrate to | | | 12.2ZB | 12.3T or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2ZC | 12.3T or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2ZD | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2ZE | 12.3 or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2ZF | 12.3(4)T11 | | | | or later | | |------------+-------------+-------------| | | Migrate to | | | 12.2ZG | 12.3(4)T11 | | | | or later | | |------------+-------------+-------------| | | Migrate to | | | 12.2ZH | 12.3(4)T11 | | | | or later | | |------------+-------------+-------------| | | Migrate to | | | 12.2ZI | 12.2(25)S | | | | or later | | |------------+-------------+-------------| | | Migrate to | | | 12.2ZJ | 12.3T or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2ZK | 12.3T or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2ZL | 12.3(7)T7 | | | | or later | | |------------+-------------+-------------| | | Migrate to | | | 12.2ZN | 12.3T or | | | | later | | |------------+-------------+-------------| | | Migrate to | | | 12.2ZO | 12.3 or | | | | later | | |------------+-------------+-------------| | 12.2ZP | Vulnerable; | | | | contact TAC | | |------------+-------------+-------------| | Affected | Rebuild | Maintenance | | 12.3-Based | | Release | |------------+-------------+-------------| | | 12.3(9c) | | | |-------------+-------------| | 12.3 | 12.3(10a) | | | |-------------+-------------| | | | 12.3(12) | |------------+-------------+-------------| | 12.3B | 12.3(5a)B3 | | |------------+-------------+-------------| | | Migrate to | | | 12.3BW | 12.3(7)T7 | | | | or later | | |------------+-------------+-------------| | | 12.3(4)T11 | | | |-------------+-------------| | | 12.3(7)T7 | | |12.3T |-------------+-------------| | | 12.3(8)T5 | | | |-------------+-------------| | | | 12.3(11)T | |------------+-------------+-------------| | | Migrate to | | | 12.3XA | 12.3(7)T7 | | | | or later | | |------------+-------------+-------------| | | Migrate to | | | 12.3XB | 12.3(8)T5 | | | | or later | | |------------+-------------+-------------| | | Migrate to | | | 12.3XC | 12.3(8)T5 | | | | or later | | |------------+-------------+-------------| | 12.3XD | 12.3(4)XD4 | | |------------+-------------+-------------| | 12.3XE | 12.3(2)XE1 | | |------------+-------------+-------------| | | Migrate to | | | 12.3XF | 12.3(11)T | | | | or later | | |------------+-------------+-------------| | | Migrate to | | | 12.3XG | 12.3(11)T | | | | or later | | |------------+-------------+-------------| | | Migrate to | | | 12.3XH | 12.3(11)T | | | | or later | | |------------+-------------+-------------| | | 12.3(7)XI3 | | | 12.3XI | - Available | | | | 2/15/05 | | |------------+-------------+-------------| | 12.3XJ | Vulnerable; | | | | contact TAC | | |------------+-------------+-------------| | 12.3XK | Vulnerable; | | | | contact TAC | | |------------+-------------+-------------| | 12.3XL | Vulnerable; | | | | contact TAC | | |------------+-------------+-------------| | 12.3XN | Vulnerable; | | | | contact TAC | | |------------+-------------+-------------| | | 12.3(4)XQ1 | | | | Release | | | 12.3XQ | date not | | | | yet | | | | determined | | |------------+-------------+-------------| | 12.3XR | Vulnerable; | | | | contact TAC | | |------------+-------------+-------------| | 12.3XS | 12.3(7)XS2 | | |------------+-------------+-------------| | 12.3XU | 12.3(8)XU4 | | |------------+-------------+-------------| | | Migrate to | | | 12.3XV | 12.3(11)T | | | | or later | | |------------+-------------+-------------| | 12.3XX | 12.3(8)XX1 | | |------------+-------------+-------------| | 12.3YA | 12.3(8)YA1 | | |------------+-------------+-------------| | 12.3YC | Vulnerable; | | | | contact TAC | | |------------+-------------+-------------| | 12.3YD | Vulnerable; | | | | contact TAC | | |------------+-------------+-------------| | | Migrate to | | | 12.3YE | 12.3(4)T11 | | | | or later | | |------------+-------------+-------------| | 12.3YF | Vulnerable; | | | | contact TAC | | |------------+-------------+-------------| | 12.3YH | Vulnerable; | | | | contact TAC | | |------------+-------------+-------------| | 12.3YJ | Vulnerable; | | | | contact TAC | | |------------+-------------+-------------| | 12.3YL | Vulnerable; | | | | contact TAC | | +----------------------------------------+ Obtaining Fixed Software ======================== Customers with Service Contracts +------------------------------- Customers with contracts should obtain upgraded software through their regular update channels. For most customers, this means that upgrades should be obtained through the Software Center on Cisco's worldwide website at http://www.cisco.com/public/sw-center/sw-ios.shtml. Customers using Third-party Support Organizations +------------------------------------------------ Customers whose Cisco products are provided or maintained through prior or existing agreement with third-party support organizations such as Cisco Partners, authorized resellers, or service providers should contact that support organization for assistance with the upgrade, which should be free of charge. Customers without Service Contracts +---------------------------------- Customers who purchase direct from Cisco but who do not hold a Cisco service contract and customers who purchase through third-party vendors but are unsuccessful at obtaining fixed software through their point of sale should get their upgrades by contacting the Cisco Technical Assistance Center (TAC). TAC contacts are as follows. * +1 800 553 2447 (toll free from within North America) * +1 408 526 7209 (toll call from anywhere in the world) * e-mail: tac@cisco.com Please have your product serial number available and give the URL of this notice as evidence of your entitlement to a free upgrade. Free upgrades for non-contract customers must be requested through the TAC. Please do not contact either "psirt@cisco.com" or "security-alert@cisco.com" for software upgrades. See http://www.cisco.com/warp/public/687/Directory/DirTAC.shtml for additional TAC contact information, including special localized telephone numbers and instructions and e-mail addresses for use in various languages. Customers may only install and expect support for the feature sets they have purchased. By installing, downloading, accessing or otherwise using such software upgrades, customers agree to be bound by the terms of Cisco's software license terms found at http://www.cisco.com/public/sw-license-agreement.html, or as otherwise set forth at Cisco.com Downloads at http://www.cisco.com/public/sw-center/sw-usingswc.shtml. Workarounds =========== The effectiveness of any workaround is dependent on specific customer situations such as product mix, network topology, traffic behavior, and organizational mission. Due to the variety of affected products and releases, customers should consult with their service provider or support organization to ensure any applied workaround is the most appropriate for use in the intended network before it is deployed. * Remove the configuration command bgp log-neighbor-changes. This feature is used to monitor BGP peer status and its removal may reduce network monitoring capabilities. More information on this command is available here: http://www.cisco.com/univercd/cc/td/doc/product/software/ios123/123cgcr/iprr... The use of networking best practices techniques can greatly reduce the probability of a network infrastructure attack. Best practices that may reduce risk in this case include: BGP MD5 +------ Under normal circumstances, due to inherent security factors in the TCP protocol, such as sequence number checks, it is difficult, but possible to forge an appropriate packet to exploit this problem. Configuring your Cisco IOS device for BGP MD5 authentication greatly increases the work necessary to forge a valid packet from a remote peer. This will not protect your peering session if a valid BGP peer generates an invalid packet. This can be configured as shown in the following example: router(config)# router bgp router(config-router)# neighbor <IP_address> password <enter_your_secret_here> It is necessary to configure the same shared MD5 secret on both peers and at the same time. Failure to do so will break the existing BGP session and the new session will not get established until the exact same secret is configured on both devices. For a detailed discussion on how to configure BGP, refer to the following document: http://www.cisco.com/en/US/products/sw/iosswrel/ps1828/products_configuratio... Once the secret is configured, it is prudent to change it periodically. The exact period must fit within your company security policy but it should not be longer than a few months. When changing the secret, again it must be done at the same time on both devices. Failure to do so will break your existing BGP session. The exception is if your Cisco IOS software release contains the integrated CSCdx23494 ( registered customers only) fix on both sides of the connection. With this fix, the BGP session will not be terminated when the MD5 secret is changed only on one side. The BGP updates, however, will not be processed until either the same secret is configured on both devices or the secret is removed from both devices. Infrastructure Access Control Lists (iACLs) +------------------------------------------ Although it is often difficult to block traffic transiting your network, it is possible to identify traffic that should never be allowed to target your infrastructure devices and block that traffic at the border of your network. Infrastructure ACLs are considered a network security best practice and should be considered as a long-term addition to good network security as well as providing some added protection for this specific vulnerability. The white paper entitled "Protecting Your Core: Infrastructure Protection Access Control Lists" presents guidelines and recommended deployment techniques for infrastructure protection ACLs: http://www.cisco.com/warp/public/707/iacl.html Exploitation and Public Announcements ===================================== The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerability described in this advisory. This vulnerability was discovered by Cisco during internal testing. Status of This Notice: FINAL ============================ THIS ADVISORY IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTY OF MERCHANTABILITY. YOUR USE OF THE INFORMATION ON THE ADVISORY OR MATERIALS LINKED FROM THE ADVISORY IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS NOTICE AT ANY TIME. A stand-alone copy or paraphrase of the text of this security advisory that omits the distribution URL in the following section is an uncontrolled copy, and may lack important information or contain factual errors. Distribution ============ This advisory will be posted on Cisco's worldwide website at http://www.cisco.com/warp/public/707/cisco-sa-20050126-bgp.shtml In addition to worldwide web posting, a text version of this notice is clear-signed with the Cisco PSIRT PGP key and is posted to the following e-mail and Usenet news recipients. * cust-security-announce@cisco.com * first-teams@first.org (includes CERT/CC) * bugtraq@securityfocus.com * vulnwatch@vulnwatch.org * cisco@spot.colorado.edu * cisco-nsp@puck.nether.net * full-disclosure@lists.netsys.com * comp.dcom.sys.cisco@newsgate.cisco.com Future updates of this advisory, if any, will be placed on Cisco's worldwide website, but may or may not be actively announced on mailing lists or newsgroups. Users concerned about this problem are encouraged to check the above URL for any updates. Revision History ================ +----------------------------------------+ | Revision | | Initial | | 1.0 | 2005-January-26 | public | | | | release. | +----------------------------------------+ Cisco Security Procedures ========================= Complete information on reporting security vulnerabilities in Cisco products, obtaining assistance with security incidents, and registering to receive security information from Cisco, is available on Cisco's worldwide website at http://www.cisco.com/en/US/products/products_security_vulnerability_policy.h.... This includes instructions for press inquiries regarding Cisco security notices. All Cisco security advisories are available at http://www.cisco.com/go/psirt. - ----------------------------------------------------------------------- All contents are Copyright � 1992-2005 Cisco Systems, Inc. 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