Security Experts:

Critical WebEx Flaws Allow Remote Code Execution

Cisco has updated the WebEx extensions for Chrome and Firefox to address critical remote code execution vulnerabilities identified by researchers working for Google and Divergent Security.

Google Project Zero’s Tavis Ormandy and Cris Neckar of Divergent Security, a former member of the Chrome Security Team, discovered earlier this month that the WebEx extension allows a remote attacker to execute arbitrary code with the privileges of the web browser due to some changes made recently by Cisco.

The security holes, tracked as CVE-2017-6753, were reported to the networking giant on July 6 and they were addressed roughly one week later with the release of version 1.0.12. On Monday, both Cisco and Google Project Zero published advisories detailing the flaws.

According to Cisco, the vulnerabilities are caused by a “design defect” and they can be exploited by an attacker by getting the targeted user to visit a specially crafted webpage. The browser extensions for WebEx Meetings Server, WebEx Centers and WebEx Meetings running on Windows are impacted.

Updates have also been released for the Internet Explorer version of the WebEx plugin, which shares components with the Chrome and Firefox versions, and the WebEx desktop application. Cisco has informed customers that workarounds are not available.

Cisco said it was not aware of any attacks exploiting the vulnerabilities. However, the advisory published by Google Project Zero includes technical details and a working exploit. It also includes details on how Cisco addressed the issues.

This is not the first time Ormandy has found a critical vulnerability in the WebEx plugins. The researcher discovered a remote code execution flaw in January, which led to Google and Mozilla temporarily removing the WebEx extension from their stores.

Cisco’s initial fix turned out to be incomplete and it took the company several days to release proper patches after Ormandy’s disclosure.

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Eduard Kovacs is an international correspondent for SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.