Media Developments

Zoom Working on Patch for Code Execution Vulnerability in Windows Client

14 July, 2020 | Security Notices

Zoom is working on resolving a remote code execution vulnerability affecting the Windows client, but a third-party fix has been made available for users who don’t want to wait for the official patch. [Update: patch available]

On Thursday, ACROS Security announced the availability of a micro-patch for a remote code execution vulnerability in Zoom Client for Windows.

The issue can be exploited to execute code remotely on the victim’s machine by tricking the user into opening a document file or performing a similar action. The user won’t receive any form of warning during the attack, says ACROS, which is well known for its 0patch service.

After analyzing the security bug, ACROS determined that it is exploitable on Windows 7 and older platform versions only.

Microsoft ended official support for Windows 7 at the beginning of 2020, but millions of users continue to run it both at home and on corporate computers. Extended support is available for specific licenses.

0patch’s security researchers released a micropatch that removes the vulnerability in four different areas of the code, and ported the fix from Zoom Client for Windows 5.1.2 to the previous five versions of the application, back to 5.0.3.

“Zoom Client features a fairly persistent auto-update functionality that is likely to keep home users updated unless they really don't want to be. However, enterprise admins often like to keep control of updates and may stay a couple of versions behind, especially if no security bugs were fixed in the latest versions (which is currently the case),” 0patch notes.

0patch, which published a video showing the vulnerability being exploited in an attack, notes that Windows 10 and Windows 8 machines are not affected.

The micropatch is available for free and will remain as such until an official fix will arrive from Zoom itself. The company has been informed on the existence of the vulnerability, but has yet to release an official patch.

“Zoom takes all reports of potential security vulnerabilities seriously. Yesterday morning we received a report of an issue impacting users running Windows 7 and older. We have confirmed this issue and are currently working on a patch to quickly resolve it,” a Zoom spokesperson said, responding to a SecurityWeek inquiry.

“We'd like to thank the security researcher who shared the vulnerability with us so we could provide quick protection for our existing users and everyone else affected,” 0patch notes, adding that, should Zoom award a bug bounty for the vulnerability, the money will be “waived in favor of a charity of researcher's choice.”

UPDATE. Zoom told SecurityWeek that it has released a patch. The company has provided the following statement:

Zoom addressed this issue, which impacts users running Windows 7 and older, in the 5.1.3 client release on July 10. Users can help keep themselves secure by applying current updates or downloading the latest Zoom software with all current security updates from https://zoom.us/download."

By Ionut Arghire on July 10, 2020