==================================================================== CERT-Renater Note d'Information No. 2020/VULN559 _____________________________________________________________________ DATE : 08/10/2020 HARDWARE PLATFORM(S): / OPERATING SYSTEM(S): Windows running Cisco Webex Teams for Windows versions prior to 3.0.16269.0. ===================================================================== https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-webex-teams-dll-drsnH5AN _____________________________________________________________________ Cisco Webex Teams Client for Windows DLL Hijacking Vulnerability High Advisory ID: cisco-sa-webex-teams-dll-drsnH5AN First Published: 2020 October 7 16:00 GMT Version 1.0: Final Workarounds: No workarounds available Cisco Bug IDs: CSCvu86655 CVSS Score: Base 7.8 CVE-2020-3535 CWE-427 Summary 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 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 There are no workarounds that address this vulnerability. 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 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 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 Cisco would like to thank Hou JingYi of Qihoo 360 CERT for reporting this vulnerability. URL https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-webex-teams-dll-drsnH5AN Revision History Version Description Section Status Date 1.0 Initial public release. — Final 2020-OCT-07 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. ========================================================= + CERT-RENATER       |    tel : 01-53-94-20-44          + + 23/25 Rue Daviel   |    fax : 01-53-94-20-41         + + 75013 Paris        |    email:cert@support.renater.fr + =========================================================