Advisory ID: cisco-sa-20040818-ospfRevision 1.4
For Public Release 2004 August 18 15:00 UTC (GMT)
A Cisco device running Internetwork Operating System (IOS) ® and
enabled for the Open Shortest Path First (OSPF) protocol is vulnerable to a
Denial of Service (DoS) attack from a malformed OSPF packet. The OSPF protocol
is not enabled by default.
The vulnerability is only present in Cisco IOS release trains based on
12.0S, 12.2, and 12.3. Releases based on 12.0, 12.1 mainlines, and all Cisco
IOS images prior to 12.0 are not affected.
Cisco has made free software available to address this
vulnerability.
There are workarounds available to mitigate the effects.
This advisory is available at
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20040818-ospf.
This section provides details on affected products.
This vulnerability was introduced by a code change that was committed
to the 12.0S, 12.2, and 12.3 based release trains, causing these trains to be
vulnerable. All Cisco devices running a vulnerable release train and running
OSPF process are vulnerable.
Some release trains that are not vulnerable are explicitly listed below
for clarification. The release trains that are not mentioned below are not
vulnerable.
|
Release Train
|
Vulnerable Versions
|
|
10.x based releases
|
Not vulnerable
|
|
11.x based releases
|
Not vulnerable
|
|
12.0 based releases (except for 12.0.S based
releases)
|
Not vulnerable
|
|
12.1 based releases
|
Not vulnerable
|
|
12.0.S
|
12.0(22)S and later
|
|
12.0.SX
|
12.0(23)SX and later
|
|
12.0.SY
|
12.0(22)SY and later
|
|
12.0.SZ
|
12.0(23)SZ and later
|
|
12.2 mainline
|
Not vulnerable
|
|
12.2.B
|
12.2(15)B and later
|
|
12.2.BC
|
12.2(15)BC and later
|
|
12.2.BX
|
12.2(15)BX and later
|
|
12.2.BZ
|
12.2(15)BZ and later
|
|
12.2.CX
|
12.2(15)CX and later
|
|
12.2.EW
|
12.2(18)EW and later
|
|
12.2.MC
|
12.2(15)MC1 and later
|
|
12.2.S
|
12.2(18)S and later
|
|
12.2.SE
|
12.2(18)SE and later
|
|
12.2.SV
|
12.2(18)SV and later
|
|
12.2.SW
|
12.2(18)SW and later
|
|
12.2.SZ
|
12.2(14)SZ and later
|
|
12.2.T
|
12.2(15)T and later
|
|
12.2.YU
|
12.2(11)YU and later
|
|
12.2.YV
|
12.2(11)YV and later
|
|
12.2.ZD
|
12.2(13)ZD and later
|
|
12.2.ZE
|
12.2(13)ZE and later
|
|
12.2.ZF
|
12.2(13)ZF and later
|
|
12.2.ZG
|
12.2(13)ZG and later
|
|
12.2.ZH
|
12.2(13)ZH and later
|
|
12.2.ZJ
|
12.2(15)ZJ and later
|
|
12.2.ZK
|
12.2(15)ZK and later
|
|
12.2.ZL
|
12.2(15)ZL and later
|
|
12.2.ZN
|
12.2(15)ZN and later
|
|
12.2.ZO
|
12.2(15)ZO and later
|
|
12.3
|
All 12.3 releases
|
|
12.3.B
|
All 12.3.B releases
|
|
12.3.BW
|
All 12.3.BW releases
|
|
12.3.T
|
All 12.3.T releases
|
|
12.3.XA
|
All 12.3.XA releases
|
|
12.3.XB
|
All 12.3.XB releases
|
|
12.3.XC
|
All 12.3.XC releases
|
|
12.3.XE
|
All 12.3.XE releases
|
A Cisco device which is running an OSPF process will have a line in the
configuration defining the process number, which can be seen by issuing the
command show running-config:
router ospf {process number}
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
Cisco 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 Cisco 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 Cisco 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.
These products are confirmed not vulnerable:
-
Products that are not running Cisco IOS are not
affected.
-
Products running Cisco IOS versions 12.0 and earlier (excluding 12.0
S), 12.1 mainline and 12.2 mainline are not vulnerable.
-
Products running IOS release trains that are not mentioned in the
above table are not vulnerable.
-
Products running any version of Cisco IOS that do
not have OSPF configured are not
vulnerable.
OSPF is a routing protocol defined by RFC 2328. It is designed to
manage IP routing inside an Autonomous System (AS). OSPF packets use IP
protocol number 89.
A vulnerability exists in the processing of an OSPF packet that can be
exploited to cause the reload of a system.
Since OSPF needs to process unicast packets as well as multicast
packets, this vulnerability can be exploited remotely. It is also possible for
an attacker to target multiple systems on the local segment at a time.
Using OSPF Authentication as described in the workarounds section can
be used to mitigate the effects of this vulnerability. Using OSPF
Authentication is a highly recommended security best practice
A Cisco device receiving a malformed OSPF 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 CSCec16481.
Successful exploitation of this vulnerability results in a reload of
the device. Repeated exploitation could result in a sustained DoS
attack.
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. In some cases, no rebuild of a particular release is planned; this is
marked with the label "Not scheduled." 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 vulnerability. Although
it receives less testing, it contains only the minimal changes necessary to
effect the repair. Cisco has made available several rebuilds of mainline trains
to address this vulnerability, but strongly recommends running only the latest
maintenance release on mainline trains.
-
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 through 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 section following this table.
|
Major Release
|
Availability of Repaired Releases
|
|
Affected 12.0-Based Release
|
Rebuild
|
Interim
|
Maintenance
|
|
12.0(22)S and later
|
12.0(22)S6
|
|
|
| |
|
12.0(23)S5
|
|
|
12.0(24)S2c
|
|
|
|
12.0(24)S4
|
|
|
|
12.0(25)S1d
|
|
|
|
12.0(25)S2
|
|
|
|
12.0(26)S1
|
|
12.0(27)S
|
| |
|
12.0(23)SX and later
|
12.0(25)SX2
|
|
|
|
12.0(22)SY and later
|
Migrate to 12.0(23)S5 or later
|
|
|
|
12.0(23)SZ and later
|
|
|
12.0(27)SZ
|
|
Affected 12.2-Based Release
|
Rebuild
|
Interim
|
Maintenance
|
|
12.2(15)B and later
|
Migrate to 12.3(4)T or later
|
|
|
|
12.2(15)BC and later
|
12.2(15)BC1c
|
|
|
|
12.2(15)BC2
|
|
12.2(15)BX and later
|
Migrate to 12.3(7)XI1 or later
|
|
|
|
12.2(15)BZ and later
|
Migrate to 12.3(7)XI1 or later
|
|
|
|
12.2(15)CX and later
|
Migrate to 12.2(15)BC2 or later
|
|
|
|
12.2(18)EW
|
12.2(18)EW1
|
|
12.2(20)EW
|
|
12.2(15)MC1 and later
|
12.2(15)MC2a available upon request
|
|
|
|
12.2(18)S and later
|
12.2(20)S
12.2(18)S5
|
|
|
|
12.2(18)SE and later
|
|
|
12.2(20)SE
|
|
12.2(18)SV and later
|
|
|
12.2(22)SV
|
|
12.2(18)SW and later
|
|
|
12.2(20)SW
|
|
12.2(14)SZ and later
|
Migrate to 12.2(20)S4 or later
|
|
|
|
12.2(15)T and later
|
12.2(15)T8
|
|
|
|
12.2(11)YU and later
|
Migrate to 12.3(4)T or later
|
|
|
|
12.2(11)YV and later
|
Migrate to 12.3(4)T or later
|
|
|
|
12.2(13)ZD and later
|
Migrate to 12.3T or later
|
|
|
|
12.2(13)ZE and later
|
Migrate to 12.3 or later
|
|
|
|
12.2(13)ZF and later
|
Migrate to 12.3(4)T or later
|
|
|
|
12.2(13)ZG and later
|
Migrate to 12.3(4)T or later
|
|
|
|
12.2(13)ZH and later
|
Migrate to 12.3(4)T or later
|
|
|
|
12.2(15)ZJ and later
|
Migrate to 12.3T or later
|
|
|
|
12.2(15)ZK and later
|
12.2(15)ZK2
|
|
|
|
12.2(15)ZL and later
|
Migrate to 12.3(7)T or later
|
|
|
|
12.2(15)ZN and later
|
Migrate to 12.3(2)T4 or later
|
|
|
|
12.2(15)ZO and later
|
Migrate to 12.2(15)T8 or later
|
|
|
|
Affected 12.3-Based Release
|
Rebuild
|
Interim
|
Maintenance
|
|
12.3
|
12.3(3f)
|
|
12.3(5)
|
|
12.3B
|
12.3(5a)B
|
|
|
|
12.3BW
|
Migrate to 12.3B or later
|
|
|
|
12.3T
|
12.3(2)T4
|
|
12.3(4)T
|
|
12.3XA
|
Migrate to 12.3(7)T or later
|
|
|
|
12.3XB
|
12.3(2)XB3
|
|
|
|
12.3XC
|
Migrate to 12.3(8)T or later
|
|
|
|
12.3XE
|
Migrate to 12.3(8)T or later
|
|
|
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.
There are multiple workarounds available to mitigate the effects of
this vulnerability.
OSPF authentication may be used as a workaround. OSPF packets without a
valid key will not be processed. MD5 authentication is highly recommended, due
to inherent weaknesses in plain text authentication. With plain text
authentication, the authentication key will be sent unencrypted over the
network, which can allow an attacker on a local network segment to capture the
key by sniffing packets.
Refer to
http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a0080094069.shtml
for more information about OSPF authentication.
Although it is often difficult to block traffic transiting your
network, it is possible to identify traffic which 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 a workaround for this specific vulnerability. The white paper
"Protecting Your Core: Infrastructure Protection Access Control Lists" presents
guidelines and recommended deployment techniques for infrastructure protection
ACLs:
http://www.cisco.com/en/US/tech/tk648/tk361/technologies_white_paper09186a00801a1a55.shtml.
Cisco has made free software available to address this vulnerability
for affected customers. Prior to deploying software, customers should consult
their maintenance provider or check the software for feature set compatibility
and known issues specific to their environment.
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/en/US/docs/general/warranty/English/EU1KEN_.html,
or as otherwise set forth at Cisco.com Downloads at
http://www.cisco.com/public/sw-center/sw-usingswc.shtml.
Do not contact either "psirt@cisco.com" or "security-alert@cisco.com"
for software upgrades.
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.
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 guidance and assistance with the appropriate course of
action in regards to this advisory.
The effectiveness of any workaround or fix 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 or fix is the most appropriate
for use in the intended network before it is deployed.
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
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.
Refer to
http://www.cisco.com/en/US/support/tsd_cisco_worldwide_contacts.html
for additional TAC contact information, including special localized telephone
numbers and instructions and e-mail addresses for use in various
languages.
The Cisco PSIRT is not aware of any public announcements or malicious
use of the vulnerability described in this advisory.
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 in the following section is an uncontrolled copy, and may lack important information or contain factual errors.
This advisory will be posted on Cisco's worldwide website at
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20040818-ospf.
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 1.4
|
2005-March-29
|
In the Software Versions and Fixes section under "Affected
12.2-Based Release" for "12.2(15)BX and later, changed the rebuild cell
"12.2(16)BX Migrate to 12.3(7)XI1 or later" to "Migrate to 12.3(7)XI1 or
later."
|
|
Revision 1.3
|
2004-August-27
|
Removed the sentences "Several parameters need to be known by an
attacker to successfully exploit this vulnerability. These are the OSPF area
number, netmask, hello, and dead timers that are configured on the targeted
interface." from the Details section.
|
|
Revision 1.2
|
2004-August-21
|
In the IOS fixed software table, for the row "12.2(18)S and
later," moved 12.2(20)S from Maintenance column to Rebuild column.
|
|
Revision 1.1
|
2004-August-20
|
Added text above the table in the Software Versions and Fixes
section.
In the IOS fixed software table, for the row "12.2(18)EW," added
12.2(20)EW to the Maintenance column. In the IOS fixed software tables, removed
"*" and "**" removed from the table headings.
|
|
Revision 1.0
|
2004-August-18
|
Initial public release.
|
|
