Cisco Security Advisory
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AV:R/AC:L/Au:NR/C:N/I:N/A:C/B:N/E:H/RL:W/RC:C
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Cisco devices running an affected version of Internetwork Operating System (IOS) which supports Session Initiation Protocol (SIP) are affected by a vulnerability that may lead to a reload of the device when receiving a specific series of packets destined to port 5060. This issue is compounded by a related bug which allows traffic to TCP 5060 and UDP port 5060 on devices not configured for SIP.
There are no known instances of intentional exploitation of this issue. However, Cisco has observed data streams that appear to be unintentionally triggering the vulnerability.
Workarounds exist to mitigate the effects of this problem on devices which do not require SIP.
This advisory is posted at https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20070131-sip.
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Vulnerable Products
Any Cisco device which runs a vulnerable version of IOS and supports SIP processing could be vulnerable. This includes IOS versions 12.3(4)XH, 12.3(4)XQ, 12.3(7)XR, 12.3(7)XS, 12.3(8)JA, 12.3(8)T, 12.3(8)XU, 12.3(8)XW, 12.3(8)XX, 12.3(8)XY, 12.3(8)YA, 12.3(8)YG, 12.3(8)YH, 12.3(8)YI, 12.3(8)ZA, 12.4 Mainline and 12.4T onward. Routers configured as SIP Public Switched Telephone Network (PSTN) Gateways are vulnerable, as are routers configured as SIP Session Border Controllers (SBCs) and the CAT6000-CMM card.
To determine if your device has SIP enabled, enter the commands show ip sockets and show tcp brief all. Below is an example of a router running code without the fix, and without the workaround enabled. The router in this example is running the vulnerable image c7200-p-mz.124-3.bin:
Router#show ip sockets Proto Remote Port Local Port In Out Stat TTY OutputIF 17 0.0.0.0 0 --any-- 5060 0 0 211 0 17 0.0.0.0 0 192.168.100.2 67 0 0 2211 0 17 0.0.0.0 0 192.168.100.2 2517 0 0 11 0
The first line with UDP Port 5060 shows that UDP SIP is enabled.
Router#show tcp brief all TCB Local Address Foreign Address (state) 2051E680 *.5060 *.* LISTEN
The above lines with *.5060 show that TCP SIP is enabled.
Products Confirmed Not Vulnerable
Devices that do not support SIP processing are not affected by this issue. This includes but is not limited to the 6500, 7600, 10000 series and 12000 series. To confirm that a device is not vulnerable to this issue, ensure that ports TCP 5060 and UDP 5060 are not open on the device with the commands show tcp brief all and show ip sockets. Below is an example of a router running the fixed image c7200-js-mz.124-5b.bin which is not vulnerable to this issue.
Router#show tcp brief all Router#show ip sockets Proto Remote Port Local Port In Out Stat TTY OutputIF 17 0.0.0.0 0 192.168.100.2 67 0 0 2211 0
No lines with UDP Port 5060 are shown and UDP SIP is not enabled. In this example, UDP port 67 is used by DHCP which is not related to this vulnerability.
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SIP is a protocol designed for use in IP voice networks and is widely used for Voice over Internet Protocol (VoIP) communications worldwide.
Cisco devices running certain versions of IOS with support for SIP services may be affected by a vulnerability that leads to a reload of the device with a crafted series of SIP packets to either TCP port 5060 or UDP port 5060. This vulnerability affects routers that contain any SIP configuration, including SIP gateways. This issue is being tracked as Cisco Bug ID CSCsh58082 ( registered customers only) .
In addition, certain versions of IOS with support for SIP services may process SIP messages even if they are not configured for SIP operation. To process SIP messages IOS will open UDP port 5060 and TCP port 5060 for listening. The Cisco Bug ID that documents the issue of IOS processing SIP messages without being configured for SIP operation is CSCsb25337 ( registered customers only) . The fix for this bug turns off the listening ports TCP 5060 and UDP 5060.
A device must have an open SIP port to be vulnerable to this issue. Devices which do not listen on TCP 5060 or UDP 5060 are not vulnerable. Because SIP utilizes UDP as a transport, it is possible to spoof the sender's IP address, which may defeat ACLs that permit communication to these ports from trusted IP addresses.
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Additional mitigations that can be deployed on Cisco devices within the network are available in the Cisco Applied Mitigation Bulletin companion document for this advisory: https://sec.cloudapps.cisco.com/security/center/content/CiscoAppliedMitigationBulletin/cisco-amb-20070131-sip.
Disable SIP listening ports
For devices which do not require SIP to be enabled, the simplest and most effective workaround is to disable SIP processing on the device with the following commands.
Warning: When applying this workaround to devices which are processing MGCP or H.323 calls, the device will not allow you to stop SIP processing while active calls are being processed. Under these circumstances, this workaround should be implemented during a maintenance window when active calls can be briefly stopped.
Enter configuration commands, one per line. End with CNTL/Z. Router(config)#sip-ua Router(config-sip-ua)#no transport udp Router(config-sip-ua)#no transport tcp Router(config-sip-ua)#end
After applying this workaround the commands show ip sockets and show tcp brief all will not show the device listening on UDP and TCP port 5060:
Router#show ip sockets Proto Remote Port Local Port In Out Stat TTY 17 --listen-- 9.13.32.18 2887 0 0 11 0 Router#show tcp brief all TCB Local Address Foreign Address (state) 6649A5A4 *.1720 *.* LISTEN 66CDC764 *.1723 *.* LISTEN
Control Plane Policing
For devices which do not need to run SIP, you can use Control Plane Policing (CoPP) to block all SIP access to the device. Cisco IOS software releases 12.0S, 12.2SX, 12.2S, 12.3T, 12.4, and 12.4T 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.
Warning: Because SIP utilizes UDP as a transport, it is possible to spoof the sender's IP address, which may defeat ACLs that permit communication to these ports from trusted IP addresses.
!-- Permit all TCP and UDP SIP traffic sent to all IP addresses !-- configured on all interfaces of the affected device so that it !-- will be policed and dropped by the CoPP feature. access-list 100 permit tcp any any eq 5060 access-list 100 permit udp any any eq 5060 !-- Permit (Police or Drop)/Deny (Allow) all other Layer3 and Layer4 !-- 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-sip-class match access-group 100 !-- Create a Policy-Map that will be applied to the !-- Control-Plane of the device. policy-map drop-sip-traffic class drop-sip-class drop !-- Apply the Policy-Map to the Control-Plane of the !-- device. control-plane service-policy input drop-sip-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. Additional information on the configuration and use of the CoPP feature can be found at 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.
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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) 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 (the "First Fixed Release") and the anticipated date of availability for each are listed in the "Rebuild" 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 First Fixed Release) is known to be vulnerable. The release should be upgraded at least to the indicated release or a later version (greater than or equal to the First Fixed Release label).
For more information on the terms "Rebuild" and "Maintenance," consult the following URL: http://www.cisco.com/web/about/security/intelligence/ios-ref.html.
The following table is written to indicate the vulnerable and fixed status of CSCsh58082 ( registered customers only) , which is the bug responsible for the device reload. This table also contains information about IOS releases that are fixed for CSCsb25337 ( registered customers only) , which turns off processing of SIP messages when the device is not fully configured for SIP operation. At the time of the 2.0 publishing, there are no fixes for CSCsh58082 ( registered customers only) .
Major Release
Availability of Repaired Releases
Affected 12.0-Based Release
Rebuild
Maintenance
12.0
All 12.0 releases are not vulnerable
Affected 12.1-Based Release
Rebuild
Maintenance
12.1
All 12.1 releases are not vulnerable
Affected 12.2-Based Release
Rebuild
Maintenance
12.2
All 12.2 releases are not vulnerable
Affected 12.3-Based Release
Rebuild
Maintenance
12.3
Not vulnerable
12.3B
Not vulnerable
12.3BC
Not vulnerable
12.3BW
Not vulnerable
12.3JA
Not vulnerable
12.3JEA
Not vulnerable
12.3JK
Not vulnerable
12.3JX
Not vulnerable
12.3T
Vulnerable in all 12.3(8)T and later releases
12.3TPC
Not vulnerable
12.3XA
Not vulnerable
12.3XB
Not vulnerable
12.3XC
Not vulnerable
12.3XD
Not vulnerable
12.3XE
Not vulnerable
12.3XF
Not vulnerable
12.3XG
Not vulnerable
12.3XH
Vulnerable
12.3XI
Not vulnerable
12.3XJ
Not vulnerable
12.3XK
Not vulnerable
12.3XQ
Vulnerable
12.3XR
Vulnerable
12.3XS
Not vulnerable
12.3XU
Vulnerable
12.3XW
SIP ports are closed by default in 12.3(14)YX2 or later, but routers running SIP are still vulnerable
12.3XX
SIP ports are closed by default in 12.3(8)XX2 or later, but routers running SIP are still vulnerable
12.3XY
Vulnerable
12.3YA
Not vulnerable
12.3YD
Not vulnerable
12.3YF
SIP ports are closed by default in 12.3(14)YX2 or later, but routers running SIP are still vulnerable
12.3YG
SIP ports are closed by default in 12.3(8)YG5 or later, but routers running SIP are still vulnerable
12.3YH
Not vulnerable
12.3YI
Not vulnerable
12.3YJ
Not vulnerable
12.3YK
Vulnerable
12.3YM
SIP ports are closed by default in 12.3(14)YM8 or later, but routers running SIP are still vulnerable
12.3YQ
Vulnerable
12.3YS
Not vulnerable
12.3YT
Vulnerable
12.3YU
Vulnerable
12.3YX
SIP ports are closed by default in 12.3(14)YX2 or later, but routers running SIP are still vulnerable
12.3YZ
Vulnerable
Affected 12.4-Based Release
Rebuild
Maintenance
12.4
SIP ports are closed by default in a release listed below, but routers running SIP are still vulnerable
12.4(3d)
12.4(5b)
12.4(7a)
12.4(8)
12.4MR
SIP ports are closed by default in 12.4(6)MR or later, but routers running SIP are still vulnerable
12.4SW
Vulnerable; workaround available for all 12.4SW releases where SIP ports are closed by default
12.4T
SIP ports are closed by default in a release listed below, but routers running SIP are still vulnerable
12.4(2)T5
12.4(4)T3
12.4(6)T1
12.4(9)T
12.4XA
Vulnerable
12.4XB
SIP ports are closed by default in 12.4(4)XB2 or later, but routers running SIP are still vulnerable
12.4XC
SIP ports are closed by default in 12.4(4)XC6* available 12-Feb-07; but routers running SIP are still vulnerable
12.4XD
SIP ports are closed by default in 12.4(4)XD2 or later, but routers running SIP are still vulnerable
12.4XE
Vulnerable; workaround available for all 12.4XE releases where SIP ports are closed by default
12.4XG
Not vulnerable
12.4XJ
Vulnerable; workaround available for all 12.4XJ releases where SIP ports are closed by default
12.4XP
Vulnerable; workaround available for all 12.4XP releases where SIP ports are closed by default
12.4XT
Vulnerable; workaround available for all 12.4XT releases where SIP ports are closed by default
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This issue was first reported to Cisco by a customer. There are no known instances of intentional exploitation of this issue. However, Cisco has observed data streams that appear to be unintentionally triggering the vulnerability.
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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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Show LessRevision 2.1
2007-February-10
Changed formatting and wording of advisory table.
Revision 2.0
2007-February-9
Updated document to reflect that all products with open ports 5060 are vulnerable.
Updated Vulnerable Products with voice gateways, SBCs, and CAT6000-CMM.
Updated the software table to reflect vulnerability of 12.3(4)XH, 12.3(4)XQ, 12.3(7)XR, 12.3(7)XS, 12.3(8)JA, 12.3(8)XU, 12.3(8)XW, 12.3(8)XX, 12.3(8)XY, 12.3(8)YA, 12.3(8)YH, 12.3(8)YI and 12.3(8)ZA.
Revision 1.1
2007-January-31
Added Common Vulnerability Scoring System (CVSS) scoring for all bugs mentioned in the advisory.
Added CSCsh58082 ( registered customers only) as the Cisco Bug ID that tracks the root cause of the vulnerability.
Minor wording changes.
Revision 1.0
2007-January-31
Initial public release.
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