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Cequence Finds Web Conferencing Vulnerability

Vulnerability could allow an attacker to list and view active meetings that are not protected.

Larry Loeb

October 7, 2019

3 Min Read

Cequence Security's CQ Prime Threat Research Team has bloggedthe discovery of a vulnerability in the Cisco Webex and Zoom video conferencing platforms (among others) that could allow an attacker to "enumerate" or list and view active meetings that are not protected.

This attack takes advantage of web conferencing application program interfaces (APIs) by the use of a bot which cycles through (enumerates) and discovers valid numeric meeting IDs. Given the common user practice of disabling security functionality in the program or not assigning a password, then the bad actor would be able to view or listen to an active meeting.

The attack has been given the "cute" name of "Prying-Eye vulnerability" By Cequence.

The widespread use of APIs that connect web forms to backend systems (or to other applications) make automated attacks easier to execute. Cequence says that all users should adopt the "best practice" of using vendor-supplied security functionality to protect their meetings. Directly confirming the attendee identities, if possible, is also recommended.

Mark Adams, board member at Seagate Technology PLC and Cadence Design Systemsm says: "Security of all types, from traditional network level to user best practices, is an increasingly high priority for corporate boards and ensuring web conferences are secure should be common practice. As a board member, if for example we are reviewing quarterly financials and future looking forecasts with the executive team and the meeting is compromised due to a vulnerability like this, a bad actor would be able to eavesdrop on the web conference, gaining insider information."

Driven by mobile device ubiquity as well as the move towards modular applications where APIs are used as the foundational elements of the application business logic, Cequence is finding direct-to-API attacks becoming "increasingly common." By targeting the API (as opposed to scripting a form fill) a threat actor can obtain the same benefits of ease of use, efficiency and flexibility that APIs bring to the development community.

APIs are stateless. This means the initial request as well as the response are self-contained and will have all the information needed to complete the transaction. The ubiquity and stateless nature of APIs are beneficial in many ways to the creation process, but they may also introduce challenges which traditional security technologies cannot solve.

By design, APIs do not assume a client-side component, so traditional defense techniques like Captchas or JavaScript/SDK instrumentation will not be useful.

The direct-to-API approach also makes the assumption that there is no corresponding browser or mobile app that will be used for user redirection along with associated instrumentation and cookie assignment. The result is that the API and associated application is left unprotected by developers.

WebEx and Zoom platforms were tested and found to be open to this kind of attack. There are roughly three dozen vendors in this space, and not all were tested by Cequence. WebEx responded with their own security advisory, as did Zoom. Both state that passwords for sessions are enabled by default.

This situation highlights the vulnerabilities and the problems that API use can bring to the security table. It seems prudent to always have some sort of fence around raw API use so that security can be enforced.

— Larry Loeb has written for many of the last century's major "dead tree" computer magazines, having been, among other things, a consulting editor for BYTE magazine and senior editor for the launch of WebWeek.

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About the Author(s)

Larry Loeb

Blogger, Informationweek

Larry Loeb has written for many of the last century's major "dead tree" computer magazines, having been, among other things, a consulting editor for BYTE magazine and senior editor for the launch of WebWeek. He has written a book on the Secure Electronic Transaction Internet protocol. His latest book has the commercially obligatory title of Hack Proofing XML. He's been online since uucp "bang" addressing (where the world existed relative to !decvax), serving as editor of the Macintosh Exchange on BIX and the VARBusiness Exchange. His first Mac had 128 KB of memory, which was a big step up from his first 1130, which had 4 KB, as did his first 1401. You can e-mail him at [email protected].

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