AV:N/AC:L/Au:N/C:N/I:P/A:C/E:F/RL:OF/RC:C
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Cisco 10000, uBR10012 and uBR7200 series devices use a User Datagram Protocol (UDP) based Inter-Process Communication (IPC) channel that is externally reachable. An attacker could exploit this vulnerability to cause a denial of service (DoS) condition on affected devices. No other platforms are affected.
Cisco has released software updates that address this vulnerability. Workarounds that mitigate this vulnerability are available.
This advisory is posted at https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20080924-ipc.
Note: The September 24, 2008 IOS Advisory bundled publication includes twelve Security Advisories. Eleven of the advisories address vulnerabilities in Cisco's IOS software, and one advisory addresses vulnerabilities in Cisco Unified Communications Manager. Each Advisory lists the releases that correct the vulnerability described in the Advisory.
Individual publication links are listed below:
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https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20080924-iosips
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https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20080924-ssl
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https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20080924-sip
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https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20080924-cucm
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https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20080924-vpn
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https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20080924-mfi
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https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20080924-ubr
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https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20080924-multicast
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https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20080924-sccp
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https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20080924-iosfw
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https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20080924-l2tp
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https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20080924-iosips
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Cisco 10000, uBR10012 and uBR7200 series devices that are running an affected version of Cisco IOS are affected.
Vulnerable Products
Devices that are running Cisco IOS can be identified by using the show version command. The following example shows an output taken from a Cisco 10000 series device running Cisco IOS software release 12.2(31)SB10e:
c10k#show version | include IOS Cisco IOS Software, 10000 Software (C10K3-P11-M), Version 12.2(31)SB10e, RELEASE SOFTWARE (fc1) c10k#
The following example shows an output taken from a Cisco uBR10012 series device running Cisco IOS software release 12.3(17b)BC7:
ubr10k#show version | include IOS IOS (tm) 10000 Software (UBR10K-K8P6U2-M), Version 12.3(17b)BC7, RELEASE SOFTWARE (fc1) ubr10k#
The following example shows an output taken from a Cisco uBR7200 series device running Cisco IOS software release 12.3(21a)BC2:
ubr7200#show version | include IOS IOS (tm) 7200 Software (UBR7200-IK9SU2-M), Version 12.3(21a)BC2, RELEASE SOFTWARE (fc1) ubr7200#
Please refer to the document entitled "White Paper: Cisco IOS Reference Guide" for additional information on the Cisco IOS release naming conventions. This document is available at the following link: http://www.cisco.com/warp/public/620/1.html
Any version of Cisco IOS prior to the fixed versions listed in the Software Versions and Fixes section below is vulnerable.
Products Confirmed Not Vulnerable
Cisco uBR7100 series devices are not affected.
No other Cisco products are currently known to be affected by this vulnerability.
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Cisco 10000, uBR10012 and uBR7200 series devices use a UDP-based IPC channel. This channel uses addresses from the 127.0.0.0/8 range and UDP port 1975. Cisco 10000, uBR10012 and uBR7200 series devices that are running an affected version of Cisco IOS will process IPC messages that are sent to UDP port 1975 from outside of the device. This behavior may be exploited by an attacker to cause a reload of the device, linecards, or both, resulting in a DoS condition.
Filtering unauthorized traffic destined to 127.0.0.0/8 or UDP port 1975 will mitigate this vulnerability.
This vulnerability is documented in the Cisco Bug IDs CSCsg15342 ( registered customers only) and CSCsh29217 ( registered customers only) and has been assigned Common Vulnerabilities and Exposures (CVE) ID CVE-2008-3805.
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Workarounds consist of filtering packets that are sent to 127.0.0.0/8 range and UDP packets that are sent to port 1975.
Using Interface Access Control Lists
Access lists that filter UDP packets destined to port 1975 can be used to mitigate this vulnerability. UDP port 1975 is a registered port number that can be used by certain applications. However, filtering all packets that are destined to UDP port 1975 may cause some applications to malfunction. Therefore, access lists need to explicitly deny UDP 1975 packets that are sent to any router interface IP addresses and permit transit traffic. Such access lists need to be applied on all interfaces to be effective. Since the IPC channel uses addresses from the 127.0.0.0/8 range, it is also necessary to filter packets that are sourced from or destined to this range. An example is given below:
access-list 100 deny udp any host <router-interface 1> eq 1975 access-list 100 deny udp any host <router-interface 2> eq 1975 access-list 100 deny udp any host <router-interface ...> eq 1975 access-list 100 deny ip 127.0.0.0 0.255.255.255 any access-list 100 deny ip any 127.0.0.0 0.255.255.255 access-list 100 permit ip any any interface Serial 0/0 ip access-group 100 in
Using Control Plane Policing
Control Plane Policing (CoPP) can be used to block untrusted UDP port 1975 access to the affected device. Cisco IOS software releases 12.2BC and 12.2SCA support the CoPP feature. CoPP may be configured on a device to protect the management and control planes to minimize the risk and effectiveness of direct infrastructure attacks by explicitly permitting only authorized traffic sent to infrastructure devices in accordance with existing security policies and configurations. The following example can be adapted to your network.
Note: CoPP is not supported on uBR10012 series devices.
!-- Permit all UDP/1975 traffic so that it !-- will be policed and dropped by the CoPP feature ! access-list 111 permit udp any any eq 1975 access-list 111 permit ip any 127.0.0.0 0.255.255.255 access-list 111 permit ip 127.0.0.0 0.255.255.255 any ! !-- Permit (Police or Drop)/Deny (Allow) all other Layer 3 and !-- Layer 4 traffic in accordance with existing security policies !-- and configurations for traffic that is authorized to be sent !-- to infrastructure devices ! !-- Create a Class-Map for traffic to be policed by the CoPP !-- feature ! class-map match-all drop-IPC-class match access-group 111 ! !-- Create a Policy-Map that will be applied to the Control-Plane !-- of the device ! policy-map drop-IPC-traffic class drop-IPC-class drop ! !-- Apply the Policy-Map to the Control-Plane of the device ! control-plane service-policy input drop-IPC-traffic !
In the above CoPP example, the access control list entries (ACEs) which match the potential exploit packets with the "permit" action result in these packets being discarded by the policy-map "drop" function, while packets that match the "deny" action (not shown) are not affected by the policy-map drop function.
Please note that in the Cisco IOS 12.2S and 12.0S trains the policy-map syntax is different:
! policy-map drop-IPC-traffic class drop-IPC-class police 32000 1500 1500 conform-action drop exceed-action drop !
Additional information on the configuration and use of the CoPP feature can be found at http://www.cisco.com/web/about/security/intelligence/coppwp_gs.html, http://www.cisco.com/en/US/prod/collateral/iosswrel/ps6537/ps6586/ps6642/prod_white_paper0900aecd804fa16a.html and http://www.cisco.com/en/US/docs/ios/12_3t/12_3t4/feature/guide/gtrtlimt.html.
Using Infrastructure ACLs at Network Boundary
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. iACLs are 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 iACL example shown below should be included as part of the deployed infrastructure access-list which will protect all devices with IP addresses in the infrastructure IP address range:
!-- Note: IPC packets sent to UDP destination port 1975 must not !-- be permitted from any trusted source as this traffic !-- should only be sent and received internally by the !-- affected device using an IP address allocated from the !-- 127.0.0.0/8 prefix. !-- !-- IPC that traffic that is internally generated and sent !-- and/or received by the affected device is not subjected !-- to packet filtering by the applied iACL policy. ! !-- Deny IPC (UDP port 1975) packets from all sources destined to !-- all IP addresses configured on the affected device. ! access-list 150 deny udp any host INTERFACE_ADDRESS#1 eq 1975 access-list 150 deny udp any host INTERFACE_ADDRESS#2 eq 1975 access-list 150 deny udp any host INTERFACE_ADDRESS#N eq 1975 ! !-- Deny all IP packets with a source or destination IP address !-- from the 127.0.0.0/8 prefix. ! access-list 150 deny ip 127.0.0.0 0.255.255.255 any access-list 150 deny ip any 127.0.0.0 0.255.255.255 ! !-- Permit/deny all other Layer 3 and Layer 4 traffic in accordance !-- with existing security policies and configurations. ! !-- Permit all other traffic to transit the device. ! access-list 150 permit ip any any ! !-- Apply iACL to interfaces in the ingress direction. ! interface GigabitEthernet0/0 ip access-group 150 in !
Note: iACLs that filter UDP packets destined to port 1975 can be used to mitigate this vulnerability. However, UDP port 1975 is a registered port number that can be used by certain applications. Filtering all packets that are destined to UDP port 1975 may cause some applications to malfunction. Therefore, the iACL policy needs to explicitly deny UDP packets using a destination port of 1975 that are sent to any router interface IP addresses for affected devices, then permit and/or deny all other Layer 3 and Layer 4 traffic in accordance with existing security policies and configurations, and then permit all other traffic to transit the device. iACLs must be applied on all interfaces to be used effectively. Since the IPC channel uses addresses from the 127.0.0.0/8 range, it is also necessary to filter packets that are sourced from or destined to this range as provided in the preceding example.
The white paper entitled "Protecting Your Core: Infrastructure Protection Access Control Lists" presents guidelines and recommended deployment techniques for infrastructure protection access lists. This white paper can be obtained here:
http://www.cisco.com/en/US/tech/tk648/tk361/technologies_white_paper09186a00801a1a55.shtml
Additional Mitigation Techniques
Additional mitigation techniques that can be deployed on Cisco devices within the network are available in the Cisco Applied Mitigation Bulletin companion document for this advisory, which is available at the following link:
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When considering software upgrades, also consult http://www.cisco.com/go/psirt 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) or your contracted maintenance provider for assistance.
Each row of the Cisco IOS software table (below) names a Cisco IOS release train. If a given release train is vulnerable, then the earliest possible releases that contain the fix (along with the anticipated date of availability for each, if applicable) are listed in the "First Fixed Release" column of the table. The "Recommended Release" column indicates the releases which have fixes for all the published vulnerabilities at the time of this Advisory. A device running a release in the given train that is earlier than the release in a specific column (less than the First Fixed Release) is known to be vulnerable. Cisco recommends upgrading to a release equal to or later than the release in the "Recommended Releases" column of the table.
Major Release
Availability of Repaired Releases
Affected 12.0-Based Releases
First Fixed Release
Recommended Release
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Releases prior to 12.0(32)S are vulnerable, release 12.0(32)S and later are not vulnerable;
12.0(32)S11
12.0(33)S1
Not Vulnerable
Vulnerable, migrate to 12.0S, 12.1
Not Vulnerable
Vulnerable, migrate to 12.0S, 12.1
Not Vulnerable
Not Vulnerable
12.0(30)SZ4
12.0(32)S11
12.0(33)S1
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Affected 12.1-Based Releases
First Fixed Release
Recommended Release
There are no affected 12.1 based releases
Affected 12.2-Based Releases
First Fixed Release
Recommended Release
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
12.2(31)SB13
12.2(33)SB1
12.2(33)SB2; Available on 26-SEP-08
Not Vulnerable
12.2(33)SCA1
12.2(33)SCA1
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
12.2(33)SRC2
12.2(33)SRC2
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Vulnerable; first fixed in 12.2SB
12.2(33)SB2; Available on 26-SEP-08
Not Vulnerable
Not Vulnerable
Affected 12.3-Based Releases
First Fixed Release
Recommended Release
Not Vulnerable
Not Vulnerable
12.3(17b)BC6
12.3(21a)BC1
12.3(23)BC
12.3(23)BC4
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Note: Releases prior to 12.3(14)T3 are vulnerable, release 12.3(14)T3 and later are not vulnerable;
12.4(15)T7
12.4(18c)
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
12.3(7)XI10a
12.2(33)SB2; Available on 26-SEP-08
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Affected 12.4-Based Releases
First Fixed Release
Recommended Release
Note: Releases prior to 12.4(3) are vulnerable, release 12.4(3) and later are not vulnerable;
12.4(18c)
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
Not Vulnerable
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The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerability described in this advisory.
This vulnerability was found internally.
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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.
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Revision 1.1
2009-April-16
Removed references to the combined software table, as it is now outdated
Revision 1.0
2008-Sep-24
Initial public release.
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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.