CVE-2022-22783 - Exposing Memory Fragments in Zoom On-Premise Meeting Connector

Summary:
In the fast-evolving world of cybersecurity, sometimes vulnerabilities hide in plain sight—right in the core memory of business-critical software. This deep dive explores CVE-2022-22783, a significant flaw in the Zoom On-Premise Meeting Connector Controller (version 4.8.102.20220310) and MMR (Multimedia Router) that could quietly leak confidential fragments of memory to connected clients.

What Is the Vulnerability?

Zoom’s On-Premise Meeting Connector is designed to route Zoom traffic within a company’s own servers, generally for privacy or regulatory reasons. In versions 4.8.102.20220310 of both the Meeting Connector Controller and the MMR, a logic error allows connected clients to receive more information than intended. The flaw exposes small portions of process memory, which might contain sensitive data.

A passive attacker—someone simply watching data flow by, without interfering—could spot and collect these memory fragments over time.

References

- NVD CVE-2022-22783 Reference
- Zoom Security Bulletin ZSB-22007

To understand this better, let’s break it down

- When a client connects to the Meeting Connector, the server uses buffers (temporary memory holders) to prepare and send messages.
- Due to incomplete buffer clearing or incorrect length calculations, sometimes the outgoing message includes "leftover" bytes from previous memory usage.
- These leftovers can be seen by the user’s client—meaning any data previously stored in memory by the Zoom server process is at risk of being passively observed.

This type of bug is similar to classic vulnerabilities like Heartbleed, but in a Zoom-specific context.

Simplified Proof-of-Concept (POC)

Since this vulnerability requires internal access and control, a basic proof-of-concept is provided here for educational purposes only.

Suppose you’re a client connected to the vulnerable On-Premise Meeting Connector. Normally, the server sends you a message like this (in pseudo-code):

def send_message(client, data):
    buffer = bytearray(2048)
    buffer[:len(data)] = data
    # (WRONG) buffer is sent with fixed length, not using data length
    client.send(buffer)  # Sometimes includes old memory stuff!

In a patched scenario, it should look like this

def send_message(client, data):
    client.send(data)  # Only send what is necessary!

The vulnerability arises when the server transmits all 2048 bytes—even if data is only 100 bytes long. The remaining bytes may contain memory fragments from previous operations.

If an attacker listens to this traffic (e.g., using Wireshark and access to the internal network), they might see random bytes or even readable strings, contact info, residual usernames, or snippets of previous meetings.

Sample observation (hex view)

... username=johndoe\password=Xyz123...

Attack Type: Passive, requires being able to observe raw Zoom Meeting Connector traffic.

- Impact: Disclosure of accidental memory fragments, possible recovery of sensitive information depending on what’s in the process memory at the time.
- Availability: Requires internal network access—exploits don’t work over encrypted public Zoom cloud meetings.

Repeat over time to collect more memory fragments.

Note: Real-world exploitation is limited but, over time, attackers might piece together confidential data.

Update: Upgrade to the fixed version—Zoom released 4.8.202.20220415 or later.

- Restrict Access: Make sure only authorized, trusted clients and users can connect to your on-premise Zoom infrastructure.
- Traffic Monitoring: Use tools like IDS/IPS to watch for unusual Zoom traffic patterns.

Lessons Learned

CVE-2022-22783 is a reminder that memory management and buffer handling are critical, especially in software that handles sensitive business communications. Always clear and properly size your buffers!

Timeline

Published on: 04/28/2022 15:15:00 UTC
Last modified on: 05/09/2022 18:39:00 UTC