Cisco Security Advisory Cisco WebEx Clients Remote Code Execution Vulnerability Critical Advisory ID: cisco-sa-20180418-wbs First Published: 2018 April 18 16:00 GMT Version 1.3: Final Workarounds: No workarounds available Cisco Bug IDs: CSCvg19384 CSCvi10746 CVE-2018-0112 CWE-20 CVSS Score: Base 9.0 Click Icon to Copy Verbose Score

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 CVE-2018-0112 CWE-20 Download CVRF Download PDF Email Summary



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 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: Affected Products Vulnerable Products

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 .



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. 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: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 thesection. The version of the WebEx client build will be displayed on the right side of the page under. 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. Version information for the Cisco WebEx meeting client on Mac platforms can be viewed by choosingCisco 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.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.

Details 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. Workarounds



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 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 Fixed Software 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 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. 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.

Exploitation and Public Announcements 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 This vulnerability was reported to Cisco by Alexandros Zacharis of ENISA. Cisco Security Vulnerability Policy 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. Subscribe URL https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180418-wbs Revision History Version 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 Show Less Legal Disclaimer 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. Cisco Security Vulnerability Policy 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. Subscribe