It is possible to send an Address Resolution Protocol (ARP) packet on a local broadcast interface (for example, Ethernet, cable, Token Ring, FDDI) which could cause a router or switch running specific versions of Cisco IOS® Software Release to stop sending and receiving ARP packets on the local router interface. This will in a short time cause the router and local hosts to be unable to send packets to each other. ARP packets received by the router for the router's own interface address but a different Media Access Control (MAC) address will overwrite the router's MAC address in the ARP table with the one from the received ARP packet. This was demonstrated to attendees of the Black Hat conference and should be considered to be public knowledge. This attack is only successful against devices on the segment local to the attacker or attacking host. This vulnerability is documented in Cisco Bug ID CSCdu81936, and a workaround is available. The complete notice will be available at http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20011115-ios-arp-overwrite.
It is possible to send an Address Resolution Protocol (ARP) packet on a local broadcast interface (for example, Ethernet, cable, Token Ring, FDDI) which could cause a router or switch running specific versions of Cisco IOS® Software Release to stop sending and receiving ARP packets on the local router interface. This will in a short time cause the router and local hosts to be unable to send packets to each other. ARP packets received by the router for the router's own interface address but a different Media Access Control (MAC) address will overwrite the router's MAC address in the ARP table with the one from the received ARP packet. This was demonstrated to attendees of the Black Hat conference and should be considered to be public knowledge. This attack is only successful against devices on the segment local to the attacker or attacking host.
This vulnerability is documented in Cisco Bug ID CSCdu81936, and a workaround is available.
The complete notice will be available at http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20011115-ios-arp-overwrite.
This section provides details on affected products.
The following products are affected if they run a software release that has the defect.
To determine if a Cisco product is running an affected IOS, log in to the device and issue the command show version. Cisco IOS software will identify itself as "Internetwork Operating System Software" or "IOS (tm)" software and will display a version number. Other Cisco devices either will not have the command show version, or will give different output. Compare the version number obtained from the router with the versions presented in the Software Versions and Fixes section below.
Cisco devices that may be running with affected IOS software releases include:
If you are not running Cisco IOS software, you are not affected by this vulnerability.
Cisco products that do not run Cisco IOS software and are not affected by this defect include, but are not limited to:
No other Cisco products are currently known to be affected by these vulnerabilities.
ARP packets, both request and reply, received by the router for the router's own interface address or global Network Address Translation (NAT) entries, but with a different MAC address, will overwrite the router's MAC address in the router's ARP table with the one in the ARP request or reply. Cisco IOS router devices will defend the MAC address of an interface for several attempts, but in an attempt to prevent an ARP storm, the device will accept the incorrect information into the ARP table, which causes the interface to stop accepting new ARP entries, and entries will not be accepted or updated in the ARP table. This behavior has been repaired to properly defend the interface MAC address, with rate limiting the response to avoid an ARP storm on the local network. This attack can only be carried out from the local network. This defect also impacts HSRP virtual interfaces. This defect is documented in Cisco Bug ID CSCdu81936 and is repaired in future versions of Cisco IOS code. This defect is duplicated by the following Cisco Bug ID's: CSCdv83509, CSCdv63206, CSCdv77242, CSCdv77220, CSCdu85209. Additionally, a configuration workaround is available.
The workaround for this vulnerability is to enter the router interface MAC address into the arp table with a configuration entry, sometimes known as "hard coding" the ARP table entry.
The syntax for this command for routers and switches running IOS is as follows:
arp
The caveat to this workaround is identified with defect CSCdv04366, which will clear all manually entered MAC addresses from the ARP table, when they are the same as the interface MAC address, when the command "clear arp" is issued on the router. This workaround does not survive a reboot of the router, and must be re-written to the configuration after any reload or reboot.
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 any 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, and it 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, and 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 Technical Assistance Center (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 software release names and abbreviations is available at http://www.cisco.com/warp/public/620/1.html.
|
Major Release |
Description or Platform |
Availability of Repaired Releases* |
||
|---|---|---|---|---|
|
Affected Earlier Releases |
Rebuild |
Interim** |
Maintenance |
|
|
11.1 and earlier, all variants |
Numerous |
Upgrade to repaired release or use workaround |
||
|
11.2-based Releases |
Rebuild |
Interim** |
Maintenance |
|
|
11.2 |
Major release for all platforms |
Not affected after 11.2(13) |
||
|
11.2P |
New platform support |
Not affected after 11.2(12)P |
||
|
11.3-based Releases |
Rebuild |
Interim** |
Maintenance |
|
|
11.3 |
Major release for all platforms |
Not affected after 11.3(3) |
||
|
11.3T |
Early deployment major release, feature-rich for early adopters |
Not affected after 11.3(3) |
||
|
12.0-based Releases |
Rebuild |
Interim** |
Maintenance |
|
|
12.0 |
General Deployment (GD) candidate: all platforms |
12.0(19.6) |
||
|
12.0DA |
xDSL support: 6100, 6200 |
Unavailable |
||
|
Upgrade recommended to 12.2DA |
||||
|
12.0DB |
Early deployment release for 6400 NSP |
Unavailable |
||
|
Upgrade recommended to 12.1T or later |
||||
|
12.0DC |
Early deployment release for 6400 NRP |
Unavailable |
||
|
Upgrade recommended to 12.2(2)B when available |
||||
|
12.0S |
Core/ISP support: GSR, RSP, c7200 |
12.0(21)S 2002-Jan-14 |
||
|
12.0SC |
Cable/broadband ISP: ubr7200 |
Unavailable |
||
|
Upgrade recommended to 12.1EC, or use workaround |
||||
|
12.0SL |
10000 ESR: c10k |
Unavailable |
||
|
Upgrade recommended to 12.0ST, or use workaround |
||||
|
12.0SP |
c10720 |
12.0(20)SP |
||
|
To Be Announced |
||||
|
12.0ST |
MPLS/Tag Switching, GSR 12000, 7200, 7500 |
12.0(20)ST 2001-Nov-26 |
||
|
12.0T |
Early Deployment(ED): VPN, Distributed Director, various platforms |
Unavailable |
||
|
Upgrade recommended to 12.1(11) |
||||
|
12.0W5 |
Catalyst switches: cat8510c, cat8540c, ls1010, cat8510m, cat8540m, cat5atm |
12.0(20)W5(24) |
||
|
2002-Jan-07 |
||||
|
Catalyst switches: cat2948g-L3, cat4232 |
12.0(18)W5(22a) |
|||
|
2001-Dec-1 |
||||
|
Catalyst switches: c6msm |
12.0(16)W5(21b) |
|||
|
2001-Nov-29 |
||||
|
12.0WC |
Catalyst 2900xl |
12.0(5)WC3 2002-Jan |
||
|
12.0WT |
Catalyst switches: cat4840g |
Not affected |
||
|
12.0XA |
Early Deployment (ED): limited platforms |
Unavailable |
||
|
Upgrade recommended to 12.1(11) |
||||
|
12.0XB |
Short-lived early deployment release |
Unavailable |
||
|
Upgrade recommended to 12.1(11) |
||||
|
12.0XC |
Early Deployment (ED): limited platforms |
Unavailable |
||
|
Upgrade recommended to 12.1(11) |
||||
|
12.0XD |
Early Deployment (ED): limited platforms |
Unavailable |
||
|
Upgrade recommended to 12.1(11) |
||||
|
12.0XE |
Early Deployment (ED): limited platforms |
Unavailable |
||
|
Upgrade recommended to 12.1(11)E, available 2001-Dec-10 |
||||
|
12.0XF |
Early Deployment (ED): limited platforms |
Unavailable |
||
|
Upgrade recommended to 12.1(11) |
||||
|
12.0XG |
Early Deployment (ED): limited platforms |
Unavailable |
||
|
Upgrade recommended to 12.1(11) |
||||
|
12.0XH |
Early Deployment (ED): limited platforms |
Unavailable |
||
|
Upgrade recommended to 12.1(11) |
||||
|
12.0XI |
Early Deployment (ED): limited platforms |
Unavailable |
||
|
Upgrade recommended to 12.1(11) |
||||
|
12.0XJ |
Early Deployment (ED): limited platforms |
Unavailable |
||
|
Upgrade recommended to 12.1(11) |
||||
|
12.0XK |
Early Deployment (ED): limited platforms |
Unavailable |
||
|
Upgrade recommended to 12.1(11) |
||||
|
12.0XL |
Early Deployment (ED): limited platforms |
Unavailable |
||
|
Upgrade recommended to 12.1(11) |
||||
|
12.0XM |
Short-lived early deployment release |
Unavailable |
||
|
Upgrade recommended to 12.1(11) |
||||
|
12.0XN |
Early Deployment (ED): limited platforms |
Unavailable |
||
|
Upgrade recommended to 12.1(11) |
||||
|
12.0XP |
Early Deployment (ED): limited platforms |
Unavailable |
||
|
Workaround recommended |
||||
|
12.0XQ |
Short-lived early deployment release |
Unavailable |
||
|
Upgrade recommended to 12.1(11) |
||||
|
12.0XR |
Short-lived early deployment release |
Unavailable |
||
|
Upgrade recommended to 12.1(11) |
||||
|
12.0XS |
Short-lived early deployment release |
Unavailable |
||
|
Upgrade recommended to 12.1(11)E, available 2001-DEC-10 |
||||
|
12.0XU |
Early Deployment (ED): limited platforms |
Unavailable |
||
|
Upgrade recommended or use workaround |
||||
|
12.0XV |
Short-lived early deployment release |
Unavailable |
||
|
Upgrade recommended to 12.2 |
||||
|
12.1-based Releases |
Rebuild |
Interim** |
Maintenance |
|
|
12.1 |
General Deployment (GD) candidate: all platforms |
12.1(10.3) |
12.1(11) |
|
|
12.1AA |
Dial Support |
12.1(10)AA 2001-Nov-12 |
||
|
12.1DA |
xDSL Support: 6100, 6200 |
Unavailable |
||
|
Upgrade recommended to 12.2.T |
||||
|
12.1DB |
Cisco 6400 Universal Access Concentrator |
Upgrade recommended to 12.2(2)B when available |
||
|
12.1DC |
xDSL NRP support: c6400r |
Upgrade recommended to 12.2(2)B when available |
||
|
12.1E |
Core/ISP Support: GSR, RSP, c7200 |
12.1(11)E 2001-DEC-10 |
||
|
Catalyst 6000 |
12.1(08a)E05 |
|||
|
12.1EA |
Catalyst 2950 |
12.1(6)EA2 2001-Dec |
||
|
Catalyst 3550 |
12.1(6)EA1a 2001-DEC |
|||
|
12.1EC |
Early Deployment (ED): ubr7200, UBR Headend platforms |
12.1(8.5)EC |
12.1(9)EC |
|
|
12.1EX |
Catalyst 6000 |
Unavailable |
||
|
Upgrade recommended to 12.1(11)E |
||||
|
12.1EY |
Catalyst 8510, 8540, LS1010 |
Not Affected |
||
|
12.1EZ |
Early Deployment (ED): limited platforms |
12.1(6)EZ4 2001-Nov-02 |
||
|
12.1T |
New technology Early Deployment (ED): all platforms |
Unavailable |
||
|
Upgrade recommended to 12.2 |
||||
|
12.1XA |
Early Deployment (ED): limited platforms |
Unavailable |
||
|
Upgrade recommended to 12.2 |
||||
|
12.1XB |
Early Deployment (ED): limited platforms |
Unavailable |
||
|
Upgrade recommended to 12.2 |
||||
|
12.1XC |
Early Deployment (ED): limited platforms |
Unavailable |
||
|
Upgrade recommended to 12.2 |
||||
|
12.1XD |
Early Deployment (ED): limited platforms |
Unavailable |
||
|
Upgrade recommended to 12.2 |
||||
|
12.1XE |
Early Deployment (ED): limited platforms |
Unavailable |
||
|
Upgrade recommended to 12.2 |
||||
|
12.1XF |
Early Deployment (ED): limited platforms |
12.1(2)XF5 2002-Jan |
||
|
12.1XG |
Early Deployment (ED): limited platforms |
12.1(3)XG6 2002-Jan |
||
|
12.1XH |
Early Deployment (ED): limited platforms |
Unavailable |
||
|
Upgrade recommended to 12.2 |
||||
|
12.1XI |
Early Deployment (ED): limited platforms |
Unavailable |
||
|
Upgrade recommended to 12.2 |
||||
|
12.1XJ |
Early Deployment (ED): limited platforms |
Unavailable |
||
|
Upgrade recommended to 12.2 |
||||
|
12.1XK |
Early Deployment (ED): limited platforms |
Unavailable |
||
|
Upgrade recommended to 12.2 |
||||
|
12.1XL |
Early Deployment (ED): limited platforms |
Unavailable |
||
|
Upgrade recommended to 12.2 |
||||
|
12.1XM |
Early Deployment (ED): limited platforms |
12.1(5)XM6 2001-Dec-03 |
||
|
12.1XP |
Early Deployment (ED): limited platforms |
Unavailable |
||
|
Upgrade recommended to 12.2(2)T |
||||
|
12.1XQ |
Early Deployment (ED): limited platforms |
Unavailable |
||
|
Upgrade recommended to 12.2(2)T |
||||
|
12.1XR |
Early Deployment (ED): limited platforms |
Unavailable |
||
|
Upgrade recommended to 12.2(7)T |
||||
|
12.1XS |
Early Deployment (ED): limited platforms |
12.2(2)XC1 2001-DEC-3 |
||
|
12.1XT |
Early Deployment (ED): limited platforms |
Unavailable |
||
|
Upgrade recommended to 12.2(7)T |
||||
|
12.1XU |
Early Deployment (ED): limited platforms |
Not affected |
||
|
12.1XV |
Early Deployment (ED): limited platforms |
12.2(2)XB2 2001-DEC-17 |
12.2(2)XB2 2001-DEC-17 |
|
|
12.1XW |
Early Deployment (ED): limited platforms |
12.1(11) |
||
|
12.1XX |
Early Deployment (ED): limited platforms |
12.1(11) |
||
|
12.1YA |
Early Deployment (ED): limited platforms |
12.2(2)XB |
||
|
12.1YB |
Early Deployment (ED): limited platforms |
12.1(5)YB5 2002-Jan |
||
|
12.1YC |
Early Deployment (ED): limited platforms |
12.1(5)YC2 2002-Jan |
||
|
12.1YD |
Early Deployment (ED): limited platforms |
Migrate to 12.2(7)T |
||
|
12.1YE |
Early Deployment (ED): limited platforms |
12.1(5)YE4 2001-Nov-19 |
||
|
12.1YF |
Early Deployment (ED): limited platforms |
12.1(5)YF3 2001-Nov |
||
|
12.1YH |
Early Deployment (ED): limited platforms |
Not Affected |
||
|
Affected 12.2-based Releases |
Rebuild |
Interim** |
Maintenance |
|
|
12.2 |
General Deployment (GD) candidate: all platforms |
12.2(4.2) |
12.2(5) |
|
|
12.2DD |
7200, 7400 |
12.2(2)DD1 2001-Nov-19 |
||
|
12.2T |
Early Deployment (ED): limited platforms |
12.2(7)T 2002-Feb |
||
|
12.2XA |
Early Deployment (ED): limited platforms |
12.2(2)XA4 2001-Dec-3 |
||
|
12.2XB |
Early Deployment (ED): limited platforms |
12.2(2)XB2 2001-Dec-17 |
||
|
12.2XC |
Early Deployment (ED): limited platforms |
12.2(2)XC1 2001-DEC-3 |
||
|
12.2XD |
Early Deployment (ED): limited platforms |
12.2(1)XD3 2002-Jan |
||
|
12.2XE |
Early Deployment (ED): limited platforms |
12.2(1)XE2 2002-Jan |
||
|
12.2XG |
Early Deployment (ED): limited platforms |
12.2(2)XG1 2001-DEC-17 |
||
|
12.2XH |
Early Deployment (ED): limited platforms |
12.2(2)XH2 2002-Jan |
||
|
12.2XI |
Early Deployment (ED): limited platforms |
|||
|
12.2XJ |
Early Deployment (ED): limited platforms |
12.2(2)XJ2 2002-Jan |
||
|
12.2XK |
Early Deployment (ED): limited platforms |
12.2(2)XK5 2002-Jan |
||
|
12.2XQ |
Early Deployment (ED): limited platforms |
12.2(2)XQ2 2002-Jan |
||
|
Notes |
||||
|
* All dates are estimated and subject to change. ** Interim releases are subjected to less rigorous testing than regular maintenance releases, and may have serious bugs. *** This release does not have a rebuild solution. Customers should upgrade to 12.2T when it becomes available. This is not a misprint. |
||||
This vulnerability was disclosed at the Black Hat conferences in Las
Vegas this year by Kevin DePeugh
To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.
|
Revision 1.3 |
2002-July-22 |
Updates to Software Versions and Fixes section. |
|
Revision 1.2 |
2001-December-18 |
Updates to Summary, Affected Products, Impact, Software Versions and Fixes, and Workaround sections. |
|
Revision 1.1 |
2001-November-21 |
Release table updates |
|
Revision 1.0 |
2001-November-15 |
For public release 15-NOV-2001 08:00 AM US/Pacific (UTC-0700) |
THIS DOCUMENT IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE INFORMATION ON THE DOCUMENT OR MATERIALS LINKED FROM THE DOCUMENT IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS DOCUMENT AT ANY TIME.
A stand-alone copy or paraphrase of the text of this document that omits the distribution URL is an uncontrolled copy, and may lack important information or contain factual errors. The information in this document is intended for end-users of Cisco products.
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