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A heap based buffer overflow exists in all desktop versions of the Zoom Client for Meetings before version 5.6.3. This Finding was reported to Zoom as a part of 2021 Pwn20wn Vancouver. The attack chain demonstrated during Pwn20wn was mitigated in a server-side change in Zoom’s infrastructure on 2021-04-09.
When combined with two other issues reported during Pwn20wn - improper URL validation when sending an XMPP message to access a Zoom Marketplace app URL and incorrect URL validation when displaying a GIPHY image - a malicious user can achieve remote code execution on a target’s computer.
The target must have previously accepted a Connection Request from the malicious user or be in a multi-user chat with the malicious user for this attack to succeed. The attack chain demonstrated in Pwn20wn can be highly visible to targets, causing multiple client notifications to occur.
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.
Reported by Daan Keuper and Thijs Alkemade from Computest via the Zero Day Initiative
| Revision | Date | Description |
|---|---|---|
| 1.0 | 08/13/2021 | Initial Publication |