Cisco Security Advisory
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CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N/E:X/RL:X/RC:X
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A vulnerability in Cisco Unified IP Phones could allow an unauthenticated, remote attacker to impersonate another user's phone if the Cisco Unified Communications Manager (CUCM) is in secure mode.
This vulnerability is due to improper key generation during the manufacturing process that could result in duplicated manufactured keys installed on multiple devices. An attacker could exploit this vulnerability by performing a machine-in-the-middle attack on the secure communication between the phone and the CUCM. A successful exploit could allow the attacker to impersonate another user's phone.
This vulnerability cannot be addressed with software updates. There is a workaround that addresses this vulnerability.
This advisory is available at the following link:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-cp6901-dup-cert-82jdJGe4
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Vulnerable Products
At the time of publication, this vulnerability affected Cisco Unified IP Phone 6901 when the CUCM server is in secure mode. The secure mode is also known as mixed mode. Non-secure mode is the default mode of the CUCM.
This vulnerability also impacts the following Cisco IP Phones but they are past End-of-Support:
- ATA 187 Analog Telephone Adapter
- Unified IP Phone 6911
- Unified IP Phone 6921
- Unified IP Phone 6941
- Unified IP Phone 6945
- Unified IP Phone 6961
- Unified IP Phone 8941
- Unified IP Phone 8945
- Unified IP Phone 8961
- Unified IP Phone 9951
- Unified IP Phone 9971
Products Confirmed Not Vulnerable
Only products listed in the Vulnerable Products section of this advisory are known to be affected by this vulnerability.
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There is a workaround that addresses this vulnerability.
As a workaround for this vulnerability, install a Locally Significant Certificate (LSC):
- Verify that the CUCM certificate is up to date.
- Open the phone configuration page.
- Navigate to Settings > Security Configuration > LSC.
- Install the LSC.
See Configure LSC on Cisco IP Phone with CUCM for more details.
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This vulnerability cannot be addressed with software updates. There is a workaround that completely closes the attack vector for this vulnerability.
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The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.
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This vulnerability was found by Andrew Chi, David McGrew, and Brandon Enright of Cisco during internal security testing.
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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 LessVersion Description Section Status Date 1.0 Initial public release. — Final 2022-JUN-15
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