Cisco Security Advisory
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CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H/E:X/RL:X/RC:X
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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:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180418-wbs
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Vulnerable Products
This vulnerability affects clients that are 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
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.
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 vulnerability.
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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 (.swf) 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.
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There are no workarounds that address this vulnerability. However, it is possible to remove all WebEx software completely from a system by using the Meeting Services Removal Tool (for Microsoft Windows users) or Mac WebEx Meeting Application Uninstaller (for Apple Mac OS X users), both of which are available for download from the Cisco Collaboration Help for Cisco Spark, WebEx, and Jabber article at https://collaborationhelp.cisco.com/article/en-us/WBX000026396.
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://collaborationhelp.cisco.com/article/en-us/WBX28548.
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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.htmlAdditionally, 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.htmlCustomers 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
The following client builds of Cisco WebEx Business Suite (WBS31 and 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. 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 Cisco WebEx Business Suites that are on lockdown will need to contact WebEx Support to apply the appropriate patch to their WebEx site.
Note: Upon updating to the most current client build of the WebEx Suites, customers will no longer be able to share Flash (.swf) files by using the WebEx file-sharing feature.
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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.
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This vulnerability was reported to Cisco by Alexandros Zacharis of ENISA.
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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 1.3 Modified wording to reflect that the vulnerability lies in the file-sharing functionality, not the file-transfer capability embedded in WebEx. Summary, Details, Fixed Software Final 2018-May-02 1.2 Modified wording to reflect that the vulnerability lies in the file-transfer functionality, not the file-sharing capability embedded in WebEx. Summary, Details, Fixed Software Final 2018-April-25 1.1 Included information about the inability to share Flash (.swf) files via the WebEx file-sharing feature. Fixed Software Final 2018-April-19 1.0 Initial public release. — Final 2018-April-18
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