Menu
Cisco starts patching critical flaw in WebEx browser extension

Cisco starts patching critical flaw in WebEx browser extension

The vulnerability could allow attackers to remotely execute malicious code on computers

Cisco Systems has started to patch a critical vulnerability in its WebEx collaboration and conferencing browser extension that could allow attackers to remotely execute malicious code on computers.

The company released a patched version of the extension -- 1.0.7 -- for Google Chrome on Thursday and is working on similar patches for the Internet Explorer and Mozilla Firefox versions.

The vulnerability was found by Google security researcher Tavis Ormandy and stemmed from the fact that the WebEx extension exposed functionality to any website that had "cwcsf-nativemsg-iframe-43c85c0d-d633-af5e-c056-32dc7efc570b.html" in its URL or inside an iframe. Some of that WebEx functionality allowed for the execution of arbitrary code on computers.

Cisco tried to fix the problem in version 1.0.5 by restricting the sensitive features only to the *.webex.com or *.webex.com.cn domains. That didn't solve the problem completely because any cross-site scripting (XSS) vulnerability on those domains could be used to bypass the restrictions.

XSS is one of the most common types of vulnerabilities on the web and webex.com has more than 500 defined subdomains. Chances are high that multiple XSS flaws exist those websites and, in fact, Ormandy found one and proved a bypass of the initial patch.

Cisco added further restrictions in version 1.0.7 of the WebEx extension that appears to block all known bypass methods.

"It looks like they correctly handle Mac and Windows, and have also added some verification on GpcInitCall/GpcExitCall/etc so that functions have to match a RegEx," Ormandy said. "This looks like a huge improvement."

Ormandy added that he doesn't currently know of any way to defeat the new patch, so users should upgrade to the latest version as soon as possible.

The Chrome WebEx extension alone has around 20 million active users, so the risk of attacks is high, especially since details of this vulnerability have been public for days. IE and Firefox users who have the extension installed should disable it until a fixed version is released for those browsers.


Follow Us

Join the newsletter!

Or

Sign up to gain exclusive access to email subscriptions, event invitations, competitions, giveaways, and much more.

Membership is free, and your security and privacy remain protected. View our privacy policy before signing up.

Error: Please check your email address.

Events

Featured

Slideshows

Channel kicks 2021 into gear as After Hours returns to Auckland

Channel kicks 2021 into gear as After Hours returns to Auckland

After Hours made a welcome return to the channel social calendar with a bumper crowd of partners, distributors and vendors descending on The Pantry at Park Hyatt in Auckland to kick-start 2021.

Channel kicks 2021 into gear as After Hours returns to Auckland
The Kiwi channel gathers for the 2020 Reseller News Women in ICT Awards

The Kiwi channel gathers for the 2020 Reseller News Women in ICT Awards

Hundreds of leaders from the New Zealand IT industry gathered at the Hilton in Auckland on 17 November to celebrate the finest female talent in the Kiwi channel and recognise the winners of the Reseller News Women in ICT Awards (WIICTA) 2020.

The Kiwi channel gathers for the 2020 Reseller News Women in ICT Awards
Show Comments