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AUSCERT External Security Bulletin Redistribution
ESB-2020.3477
Cisco Webex Teams Client for Windows DLL Hijacking Vulnerability
8 October 2020
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AusCERT Security Bulletin Summary
---------------------------------
Product: Cisco Webex Teams client for Windows
Publisher: Cisco Systems
Operating System: Windows
Impact/Access: Execute Arbitrary Code/Commands -- Existing Account
Resolution: Patch/Upgrade
CVE Names: CVE-2020-3535
Original Bulletin:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-webex-teams-dll-drsnH5AN
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Cisco Webex Teams Client for Windows DLL Hijacking Vulnerability
Priority: High
Advisory ID: cisco-sa-webex-teams-dll-drsnH5AN
First Published: 2020 October 7 16:00 GMT
Version 1.0: Final
Workarounds: No workarounds availableCisco Bug IDs: CSCvu86655
CVE-2020-3535
CWE-427
Summary
o A vulnerability in the loading mechanism of specific DLLs in the Cisco
Webex Teams client for Windows could allow an authenticated, local attacker
to load a malicious library. To exploit this vulnerability, the attacker
needs valid credentials on the Windows system.
The vulnerability is due to incorrect handling of directory paths at run
time. An attacker could exploit this vulnerability by placing a malicious
DLL file in a specific location on the targeted system. This file will
execute when the vulnerable application launches. A successful exploit
could allow the attacker to execute arbitrary code on the targeted system
with the privileges of another user's account.
Cisco has released software updates that address this vulnerability. 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-webex-teams-dll-drsnH5AN
Affected Products
o Vulnerable Products
This vulnerability affects Cisco Webex Teams for Windows releases
3.0.13464.0 through 3.0.16040.0.
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 the following
Cisco products:
Webex Teams for Android
Webex Teams for iPhone and iPad
Webex Teams for Mac
Workarounds
o There are no workarounds that address this vulnerability.
Fixed Software
o Cisco has released free 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 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.
Fixed Releases
Cisco fixed this vulnerability in Cisco Webex Teams for Windows releases
3.0.16269.0 and later.
For information about updating the client , see the Update the Cisco Webex
Teams App to the Latest Release help article.
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 Hou JingYi of Qihoo 360 CERT 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-webex-teams-dll-drsnH5AN
Revision History
o +----------+---------------------------+----------+--------+--------------+
| Version | Description | Section | Status | Date |
+----------+---------------------------+----------+--------+--------------+
| 1.0 | Initial public release. | - | Final | 2020-OCT-07 |
+----------+---------------------------+----------+--------+--------------+
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