The Cisco 7920 Wireless IP Phone provides Voice Over IP service via IEEE 802.11b Wi-Fi networks and has a form-factor similar to a cordless phone. This product contains two vulnerabilities: The first vulnerability is an SNMP service with fixed community strings that allow remote users to read, write, and erase the configuration of an affected device. The second vulnerability is an open VxWorks Remote Debugger on UDP port 17185 that may allow an unauthenticated remote user to access debugging information or cause a denial of service. Cisco has made free software available to address these vulnerabilities for affected customers. There are workarounds available to mitigate the effects of the vulnerability. This advisory is posted at http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20051116-7920.
The Cisco 7920 Wireless IP Phone provides Voice Over IP service via IEEE 802.11b Wi-Fi networks and has a form-factor similar to a cordless phone. This product contains two vulnerabilities:
The first vulnerability is an SNMP service with fixed community strings that allow remote users to read, write, and erase the configuration of an affected device.
The second vulnerability is an open VxWorks Remote Debugger on UDP port 17185 that may allow an unauthenticated remote user to access debugging information or cause a denial of service.
Cisco has made free software available to address these vulnerabilities for affected customers. There are workarounds available to mitigate the effects of the vulnerability.
This advisory is posted at http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20051116-7920.
Fixed SNMP Community Strings
The Cisco 7920 Wireless IP Phone provides an SNMP service with fixed read-only and read-write community strings of "public" and "private", respectively. These strings cannot be changed by the user and will allow remote users to issue an SNMP GetRequest or SetRequest to the phone. SNMP can be used to retrieve and modify the device configuration, including stored user data such as phone book entries. To address this vulnerability, Cisco has provided updated software that removes the SNMP functionality from this product.
This issue is documented in Cisco bug ID CSCsb75186 ( registered customers only) .
VxWorks Debugger Port (wdbrpc, 17185/udp)
The Cisco 7920 Wireless IP Phone listens on UDP port 17185 to allow connections from a VxWorks debugger. This port may allow remote users to collect debugging information or conduct a denial of service attack against an affected device. To address this vulnerability, Cisco has provided updated software that closes UDP port 17185.
This issue is documented in Cisco bug ID CSCsb38210 ( registered customers only) .
The access-list must then be applied to all interfaces using configuration commands such as:access-list 101 permit udp host 10.1.1.1 192.168.10.0 0.0.0.255 range 161 162 access-list 101 permit udp host 10.1.1.1 192.168.10.0 0.0.0.255 port 17185 access-list 101 deny udp any 192.168.10.0 0.0.0.255 range 161 162 access-list 101 deny udp any 192.168.10.0 0.0.0.255 port 17185 access-list 101 permit ip any any
interface ethernet 0/0 ip access-group 101 in
Cisco has provided free software to address these vulnerabilities; please consult the chart below for details.
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.
Cisco Bug ID |
Affected Firmware Releases |
First Fixed Firmware Release |
---|---|---|
CSCsb75186 ( registered customers only) (SNMP) |
Release 1.0(8) and earlier |
Release 1.0(9) |
CSCsb38210 ( registered customers only) (VxWorks) |
Release 2.0 and earlier |
Release 2.01 |
This vulnerability was reported to Cisco by Shawn Merdinger and will be disclosed on November 16, 2005 at the CSI 32nd Annual Computer Security conference in Washington, DC. The Cisco PSIRT is not aware of any malicious use of the vulnerability described in this advisory.
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 1.0 |
2005-November-16 |
Initial public release. |
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