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AUSCERT External Security Bulletin Redistribution
ESB-2020.0804
Cisco Intelligent Proximity SSL Certificate Validation Vulnerability
5 March 2020
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AusCERT Security Bulletin Summary
---------------------------------
Product: Cisco Intelligent Proximity application
Cisco Jabber
Cisco Webex Meetings
Cisco Webex Teams
Cisco Meeting App
Publisher: Cisco Systems
Operating System: Cisco
Impact/Access: Access Confidential Data -- Remote/Unauthenticated
Unauthorised Access -- Remote/Unauthenticated
Resolution: None
CVE Names: CVE-2020-3155
Original Bulletin:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-proximity-ssl-cert-gBBu3RB
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Cisco Intelligent Proximity SSL Certificate Validation Vulnerability
Priority: High
Advisory ID: cisco-sa-proximity-ssl-cert-gBBu3RB
First Published: 2020 March 4 16:00 GMT
Version 1.0: Final
Workarounds: No workarounds availableCisco Bug IDs: CSCvr90871
CVE-2020-3155
CWE-295
CVSS Score:
7.4 AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N/E:X/RL:X/RC:X
Summary
o A vulnerability in the SSL implementation of the Cisco Intelligent
Proximity solution could allow an unauthenticated, remote attacker to view
or alter information shared on Cisco Webex video devices and Cisco
collaboration endpoints if the products meet the conditions described in
the Vulnerable Products section.
The vulnerability is due to a lack of validation of the SSL server
certificate received when establishing a connection to a Cisco Webex video
device or a Cisco collaboration endpoint. An attacker could exploit this
vulnerability by using man in the middle (MITM) techniques to intercept the
traffic between the affected client and an endpoint, and then using a
forged certificate to impersonate the endpoint. Depending on the
configuration of the endpoint, an exploit could allow the attacker to view
presentation content shared on it, modify any content being presented by
the victim, or have access to call controls.
This vulnerability does not affect cloud registered collaboration
endpoints.
There are no workarounds that address this vulnerability.
This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/
cisco-sa-proximity-ssl-cert-gBBu3RB
Affected Products
o Vulnerable Products
This vulnerability affects the following Cisco products if they are running
a vulnerable software release, have the Proximity feature enabled, and are
used to connect to on-premises devices:
Cisco Intelligent Proximity application
Cisco Jabber
Cisco Webex Meetings
Cisco Webex Teams
Cisco Meeting App
Cisco has not released software updates that address this vulnerability.
All software versions are affected.
Determining if the Proximity Feature Is Enabled on the Clients
The software clients listed above are affected by this vulnerability when
they are configured with the Proximity feature. However, for an attacker to
exploit this vulnerability, a collaboration endpoint would also need to
have the Proximity feature enabled. More information regarding the
configuration of the Proximity feature on the endpoints is available in the
Details and Workarounds sections of this advisory.
Cisco Intelligent Proximity Application
The Proximity feature is always enabled and cannot be disabled.
Cisco Jabber ^ 1
There are multiple methods to determine whether the Proximity feature is
enabled in Cisco Jabber:
1. In the Jabber configuration file jabber-config.xml , this feature is
enabled if the following line is not present:
<EnableProximity>false</EnableProximity>
2. In the application's preferences, navigate to Video Device . This
feature is enabled if Connect to nearest device automatically is selected.
Cisco Webex Meetings ^ 1
In the application's preferences, navigate to Video Systems . This feature
is enabled if Automatically discover nearby devices is selected.
Cisco Webex Teams ^ 1
From the Cisco Webex Control Hub, navigate to Settings and scroll to Device
Discovery . This feature is enabled if Allow the Webex Teams app to connect
to on-premises registered device is selected.
Cisco Meeting App
The Proximity feature is always enabled and cannot be disabled.
^ 1 The title of the submenu and the description of the option may vary
with the software version. This information is meant to provide a general
indication of where to find the configuration option for the Proximity
feature.
Products Confirmed Not Vulnerable
Only products listed in the Vulnerable Products section of this advisory
are known to be affected by this vulnerability.
Cisco has confirmed that this vulnerability does not affect Cisco Proximity
clients when used to connect to cloud registered devices.
Details
o The Cisco Intelligent Proximity solution allows laptops, smartphones, or
other handheld devices to automatically discover and connect to Cisco Webex
video devices and collaboration endpoints. The features available to the
client depend on the endpoint configuration, which will influence what can
be exploited by an attacker.
Configuration options can include any combination of the following:
Content share from clients: A client can present onto the screen of the
collaboration endpoint. The shared contents are presented only on the
collaboration endpoint and are not shared with other connected clients.
A MITM could read or modify the contents of the presentation.
Content share to clients: The shared contents are presented on the
screen of the collaboration endpoint and on any connected client
devices. A MITM could see any ongoing presentation shared by other
clients and alter the presentation contents viewed by the victim of the
attack.
Call controls: A client can control the Cisco collaboration endpoint in
the same way as if using the device's touch panel. For example, it is
possible to send commands to control volume or dial others. A MITM
could use this to dial in and listen in on the call, impersonate the
victim, or view any commands sent by the victim to the collaboration
endpoint, including dialed URIs.
Workarounds
o There are no workarounds that address this vulnerability.
Mitigations
Disabling the Proximity Pairing Feature
The primary purpose of the collaboration endpoints is video and content
sharing. Customers that don't require automatic endpoint discovery and
connection can disable the Proximity pairing feature.
Disabling the Proximity Pairing Feature on Cisco Webex Video Devices and on
Cisco Collaboration Endpoints
Sign in to the endpoint's web interface and navigate to Setup >
Configuration , then go to Proximity > Mode . Setting Mode to Off will
ensure that all the Proximity features are disabled. Alternatively, the
different sub-services can be disabled, which will limit exposure
accordingly.
For the Cisco IX5000 Series, navigate to Configuration > Display Frequency
and Proximity Sections . Setting Mode to Off will ensure that all the
Proximity features are disabled. Alternatively, the different sub-services
can be disabled, which will limit exposure accordingly.
Note: Once this feature is disabled on an endpoint, direct interaction with
the device is required to use it. The various Proximity clients will not be
able to connect to the endpoints. However, this doesn't prevent client
software from connecting to other endpoints that might have the feature
enabled, thus not fully eliminating the risk of exploitation.
Disabling the Automatic Discovery of Collaboration Endpoints on the
Proximity Clients
It is possible to disable the Proximity pairing in Cisco Jabber, Cisco
Webex Teams, and Cisco Webex Meetings. The instructions for how to reach
the configuration option for each respective client are listed in the
Vulnerable Products section of this advisory.
Note: Disabling this feature on the clients will not prevent external
guests from connecting to the endpoint, thus not fully eliminating the risk
of exploitation.
Migration of the Collaboration Solution to the Cloud
Customers that are entitled to use the cloud registered collaboration
solution may migrate their environment from on-premises to cloud registered
devices. The Cisco Intelligent Proximity solution for cloud registered
devices is not affected by this vulnerability.
Fixed Software
o Cisco has not released software updates that address the vulnerability
described in this advisory. Customers may only install and expect support
for software versions and feature sets for which they have purchased a
license. By installing, downloading, accessing, or otherwise using such
software upgrades, customers agree to follow the terms of the Cisco
software license: https://www.cisco.com/c/en/us/products/
end-user-license-agreement.html
Additionally, customers may only download software for which they have a
valid license, procured from Cisco directly, or through a Cisco authorized
reseller or partner. In most cases this will be a maintenance upgrade to
software that was previously purchased. Free security software updates do
not entitle customers to a new software license, additional software
feature sets, or major revision upgrades.
When considering software upgrades , customers are advised to regularly
consult the advisories for Cisco products, which are available from the
Cisco Security Advisories and Alerts page , to determine exposure and a
complete upgrade solution.
In all cases, customers should ensure that the devices to be upgraded
contain sufficient memory and confirm that current hardware and software
configurations will continue to be supported properly by the new release.
If the information is not clear, customers are advised to contact the Cisco
Technical Assistance Center (TAC) or their contracted maintenance
providers.
Customers Without Service Contracts
Customers who purchase directly from Cisco but do not hold a Cisco service
contract and customers who make purchases through third-party vendors but
are unsuccessful in obtaining fixed software through their point of sale
should obtain upgrades by contacting the Cisco TAC: https://www.cisco.com/c
/en/us/support/web/tsd-cisco-worldwide-contacts.html
Customers should have the product serial number available and be prepared
to provide the URL of this advisory as evidence of entitlement to a free
upgrade.
Exploitation and Public Announcements
o The Cisco Product Security Incident Response Team (PSIRT) is not aware of
any public announcements or malicious use of the vulnerability that is
described in this advisory.
Source
o Cisco would like to thank Adam Shore for reporting this vulnerability.
Cisco Security Vulnerability Policy
o 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.
URL
o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/
cisco-sa-proximity-ssl-cert-gBBu3RB
Revision History
o +----------+---------------------------+----------+--------+--------------+
| Version | Description | Section | Status | Date |
+----------+---------------------------+----------+--------+--------------+
| 1.0 | Initial public release. | - | Final | 2020-MAR-04 |
+----------+---------------------------+----------+--------+--------------+
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