A security researcher has discovered a vulnerability in an elevation of privilege in the update service of the Cisco Webex Meeting application. The update service fails to properly validate user-supplied parameters, according to SecureAuth.

The vulnerability was discovered by Marcos Accossatto from SecureAuth exploits' writers team, and the release of today’s vulnerability advisory was a coordinated effort between SecureAuth and Cisco. Reportedly used by millions of people each month, the video conferencing product’s flaw (CVE-2018-15442) impacts code execution in Cisco Webex Meetings v33.6.2.16 and likely affects older versions as well, though they were not checked.

With a common weakness enumeration (CWE-78) classified as OS command injection, the vulnerability could allow an unprivileged local attacker to run arbitrary commands with system user privileges by invoking the update service command with a crafted argument, according to the advisory.

In the privilege escalation proof of concept (PoC), the researcher wrote: “The vulnerability can be exploited by copying to an a local attacker controller folder, the ptUpdate.exe binary. Also, a malicious dll must be placed in the same folder, named wbxtrace.dll. To gain privileges, the attacker must start the service with the command line: sc start webexservice install software-update 1 'attacker-controlled-path' (if the parameter 1 doesn't work, then 2 should be used).”

While the video conferencing provider had fixed this vulnerability last month, Accossatto was reportedly able to bypass that fix using DLL hijacking. Cisco’s Webex Meetings has now released a new patch and updated its previous security notice.

According to Cisco's Webex Meetings website, Cisco Webex Meetings is “simply the best video conferencing and online meetings. With Cisco Webex Meetings, joining is a breeze, audio and video are clear, and screen sharing is easier than ever. We help you forget about the technology, to focus on what matters.”

However, the vulnerability in the update service of Cisco Webex Meetings desktop app for Windows, which is related to the security issue addressed in October, potentially allows a local attacker to gain elevated privileges.