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AUSCERT External Security Bulletin Redistribution
Cisco WebEx Clients Remote Code Execution Vulnerability
19 April 2018
AusCERT Security Bulletin Summary
Product: Cisco WebEx Clients
Publisher: Cisco Systems
Operating System: Windows
Impact/Access: Execute Arbitrary Code/Commands -- Existing Account
CVE Names: CVE-2018-0112
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Cisco WebEx Clients Remote Code Execution Vulnerability
Advisory ID: cisco-sa-20180418-wbs
First Published: 2018 April 18 16:00 GMT
Version 1.0: Final
Workarounds: No workarounds available
Cisco Bug IDs: CSCvg19384
CVSS Score: Base 9.0
o A vulnerability in Cisco WebEx Business Suite clients, Cisco WebEx
Meetings, and Cisco WebEx Meetings Server could allow an authenticated,
remote attacker to execute arbitrary code on a targeted system.
The vulnerability is due to insufficient input validation by the Cisco
WebEx clients. An attacker could exploit this vulnerability by providing
meeting attendees with a malicious Flash (.swf) file via the file-sharing
capabilities of the client. Exploitation of this vulnerability could allow
arbitrary code execution on the system of a targeted user.
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:
o Vulnerable Products
This vulnerability disclosed in this advisory affects the clients installed
by customers when accessing a WebEx meeting. The following client builds of
Cisco WebEx Business Suite (WBS30, WBS31, and WBS32), Cisco WebEx Meetings,
and Cisco WebEx Meetings Server are impacted by the vulnerability described
in this advisory:
- Cisco WebEx Business Suite (WBS31) client builds prior to T31.23.2
- Cisco WebEx Business Suite (WBS32) client builds prior to T32.10
- Cisco WebEx Meetings with client builds prior to T32.10
- Cisco WebEx Meetings Server builds prior to 2.8 MR2
To determine whether a Cisco WebEx Business Suite site is running an
affected version of the WebEx client build, users can log in to their Cisco
WebEx meeting site and go to the Support > Downloads section. The version
of the WebEx client build will be displayed on the right side of the page
under About Meeting Center. See the "Fixed Software" section for details.
Alternatively, version information of the Cisco WebEx meeting client can be
accessed from within the Cisco WebEx meeting client. Version information
for the Cisco WebEx meeting client on Windows and Linux platforms can be
viewed by choosing Help > About Cisco WebEx Meeting Center. Version
information for the Cisco WebEx meeting client on Mac platforms can be
viewed by choosing Meeting Center > About Cisco WebEx Meeting Center.
The Cisco WebEx software updates are cumulative in client builds. For
example, if client build 30.32.16 is fixed, build 30.32.17 will contain the
fix. Cisco WebEx site administrators have access to secondary version
nomenclature; for example, T30 SP32 EP 16, which shows that the server is
running client build 30.32.16.
Note: Customers who do not receive automatic software updates may be
running versions of Cisco WebEx that have reached end of software
maintenance and should contact customer support.
Products Confirmed Not Vulnerable
No other Cisco products are currently known to be affected by this
o The Cisco WebEx Business Suite (WBS) meeting services and Cisco WebEx
Meetings are a hosted multimedia conferencing solution that is managed and
maintained by Cisco WebEx. The Cisco WebEx Business Suite includes Cisco
WebEx Event Center, Cisco WebEx Meeting Center, Cisco WebEx Support Center,
and Cisco WebEx Training Center. The Cisco WebEx Meetings Server is a
multimedia conferencing solution that customers can host in their private
clouds. Customers download the WebEx client application to attend meetings
on the various Cisco WebEx Centers.
Exploitation of this vulnerability may cause remote code execution to occur
on the system running an affected client.
To exploit this vulnerability, the client application would require a
meeting attendee to open a malicious Flash file. An attacker may be able to
accomplish this exploit by providing the malicious .swf file directly to
users via the file-sharing capabilities of the client.
o There are no workarounds that address this vulnerability. However, it is
possible to remove all WebEx software completely from a system using the
Meeting Services Removal Tool (for Microsoft Windows users) or Mac WebEx
Meeting Application Uninstaller (for Apple Mac OS X users) available for
download from the Cisco Collaboration Help for Cisco Spark, WebEx, and
Jabber article at https://collaborationhelp.cisco.com/article/en-us/
Removal of the WebEx software from a Linux or UNIX-based system can be
accomplished by following the steps in the Cisco Collaboration Help for
Cisco Spark, WebEx, and Jabber article at https://
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
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
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:
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
The following client builds of the Cisco WebEx Business Suite (WBS31,
WBS32), Cisco WebEx Meetings, and Cisco WebEx Meetings Server address the
vulnerability described in this advisory:
- Cisco WebEx Business Suite (WBS31) client builds T31.23.2 and later
- Cisco WebEx Business Suite (WBS32) client builds T32.10 and later
- Cisco WebEx Meetings client builds T32.1 and later
- Cisco WebEx Meetings Server builds 2.8 MR2 and later
To determine whether a Cisco WebEx meeting site is running an affected
version of the WebEx client build, users can log in to their Cisco WebEx
meeting site and go to the Support > Downloads section. The version of the
WebEx client build will be displayed on the right side of the page under
About Meeting Center. The Cisco WebEx software updates are cumulative in
client builds. For example, if client build 30.32.16 is fixed, build
30.32.17 will contain updated software.
Note: Users with WebEx Business Suites that are on lockdown will need to
contact WebEx Support to apply the appropriate patch to their WebEx site.
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.
o This vulnerability was reported to Cisco by Alexandros Zacharis of ENISA.
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.
| Version | Description | Section | Status | Date |
| 1.0 | Initial public release. | - | Final | 2018-April-18 |
o THIS DOCUMENT IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND
OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR
FITNESS FOR A PARTICULAR USE. YOUR USE OF THE INFORMATION ON THE DOCUMENT
OR MATERIALS LINKED FROM THE DOCUMENT IS AT YOUR OWN RISK. CISCO RESERVES
THE RIGHT TO CHANGE OR UPDATE THIS DOCUMENT AT ANY TIME.
A standalone copy or paraphrase of the text of this document that omits the
distribution URL is an uncontrolled copy and may lack important information
or contain factual errors. The information in this document is intended for
end users of Cisco products.
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