For the second time in the year, experts found a flaw in Cisco WebEx Extension

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For the second time in a year, a highly critical remote code execution vulnerability was found in the Cisco WebEx Extension.

For the second time in a year, a highly critical remote code execution vulnerability, tracked as CVE-2017-6753, was discovered in the Cisco Systems WebEx browser extension for Chrome and Firefox. The vulnerability could be exploited by attackers to remotely execute malicious code on a target machine with the privileges of the affected browser.

“A vulnerability in Cisco WebEx browser extensions for Google Chrome and Mozilla Firefox could allow an unauthenticated, remote attacker to execute arbitrary code with the privileges of the affected browser on an affected system.” reads the security advisory published by CISCO. “This vulnerability affects the browser extensions for Cisco WebEx Meetings Server, Cisco WebEx Centers (Meeting Center, Event Center, Training Center, and Support Center), and Cisco WebEx Meetings when they are running on Microsoft Windows.”

Cisco WebEx is one of the most popular communication tools used by businesses and internet users for online meetings, webinars, and video conferences. The extension has roughly 20 million active users.

Cisco WebEx

The impact of the flaw is severe if we consider that the extension has roughly more than 20 million installs.

The vulnerability was discovered by the popular Google Project Zero hacked Tavis Ormandy and Cris Neckar of Divergent Security. The CVE-2017-6753 RCE vulnerability is due to a designing bug in the WebEx browser extension, it could allow attackers to gain control of the affected system.

The exploitation of the vulnerability is quite simple, attackers just need to trick victims into visiting a web page containing specially crafted malicious code through the browser with affected WebEx browser extension installed.

“Earlier this week a former colleague from Chrome Security, Cris Neckar from Divergent Security, pointed out that there had been some changes to the way atgpcext worked, and it looked like there may be some new problems. I see several problems with the way sanitization works, and have produced a remote code execution exploit to demonstrate them,” Ormandy said. “This extension has over 20M [million] active Chrome users alone, FireFox and other browsers are likely to be affected as well.”

Cisco acknowledged the RCE flaw and has already patched it in the “Cisco WebEx Extension 1.0.12” update for Chrome and Firefox browsers.

It is important to highlight the absence of “workarounds that address this vulnerability.”

“Cisco has released software updates for Google Chrome and Mozilla Firefox that address this vulnerability. There are no workarounds that address this vulnerability.” continues the CISCO advisory.

According to the advisory, Apple’s Safari, Microsoft Internet Explorer, and Microsoft Edge are not affected by this RCE flaw. Cisco WebEx Productivity Tools, Cisco WebEx browser extensions for Mac or Linux, and Cisco WebEx on Microsoft Edge or Internet Explorer are not affected by the vulnerability.