CVE-2023-22883: Zoom Meetings Privilege Escalation Flaw

CVE-2023-22883 Overview

CVE-2023-22883 is a local privilege escalation vulnerability affecting Zoom Client for IT Admin Windows installers before version 5.13.5. This vulnerability allows a local low-privileged user to exploit a Time-of-Check Time-of-Use (TOCTOU) race condition during the installation process to escalate their privileges to the SYSTEM user, gaining complete control over the affected Windows system.

Critical Impact

A local attacker with low privileges can exploit this vulnerability during the Zoom installation process to gain SYSTEM-level access, potentially compromising the entire Windows system and any data or applications it hosts.

Affected Products

• Zoom Meetings for Windows (versions prior to 5.13.5)
• Zoom Client for IT Admin Windows installers (versions prior to 5.13.5)

Discovery Timeline

• March 16, 2023 - CVE-2023-22883 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2023-22883

Vulnerability Analysis

This vulnerability is classified under CWE-367 (Time-of-Check Time-of-Use Race Condition), indicating a fundamental flaw in how the Zoom installer validates and processes resources during installation. The vulnerability exists in the installation routine where there is a timing window between when a security check is performed and when the checked resource is actually used.

During the installation process, the Zoom Client for IT Admin Windows installer performs operations with elevated SYSTEM privileges. The TOCTOU race condition allows an attacker to manipulate resources between the time the installer checks them and when it subsequently uses them. This timing gap creates an opportunity for privilege escalation where a low-privileged local user can inject malicious content that gets executed with SYSTEM-level permissions.

The attack requires local access to the target system and must be performed during an active installation, which limits the attack surface but still presents a significant risk in enterprise environments where IT administrators commonly deploy Zoom across multiple workstations.

Root Cause

The root cause is a Time-of-Check Time-of-Use (TOCTOU) race condition in the Zoom installer's file handling routines. The installer performs security validation on resources at one point in time but then uses those resources at a later point without re-validating, creating a window of opportunity for exploitation. This class of vulnerability typically occurs when privileged processes interact with file system objects that can be modified by unprivileged users.

Attack Vector

This is a local attack vector requiring the attacker to have low-privileged access to the target Windows system. The attacker must time their exploitation attempt to coincide with a Zoom installation operation. The attack chain typically involves:

1. Monitoring for Zoom installation activity on the target system
2. Identifying the vulnerable window during the installation process
3. Exploiting the race condition to substitute or modify resources after the security check but before use
4. The installer then processes the attacker-controlled content with SYSTEM privileges, resulting in privilege escalation

The vulnerability mechanism involves exploiting the timing gap between file validation and file usage in the Zoom installer. When the installer runs with elevated privileges, it performs checks on certain resources before processing them. An attacker can monitor for these operations and quickly substitute malicious content after the check completes but before the resource is actually consumed. This type of race condition is particularly dangerous in installers because they typically run with the highest system privileges. For detailed technical information, refer to the Zoom Security Bulletin.

Detection Methods for CVE-2023-22883

Indicators of Compromise

• Unexpected process creation with SYSTEM privileges during Zoom installation activity
• Unusual file modifications in Zoom installation directories during the installation process
• Evidence of race condition exploitation tools or scripts on the system
• Anomalous child processes spawned from the Zoom installer executable

Detection Strategies

• Monitor for suspicious file system activity during Zoom installation operations, particularly rapid file modifications in installation directories
• Implement endpoint detection rules to identify privilege escalation patterns following Zoom installer execution
• Enable detailed Windows Security Event logging (Event IDs 4688, 4689) to track process creation during installations
• Use SentinelOne's behavioral AI to detect anomalous process hierarchies where low-privileged users gain SYSTEM access

Monitoring Recommendations

• Deploy SentinelOne Singularity Platform for real-time monitoring of privilege escalation attempts
• Enable file integrity monitoring on directories commonly used during software installation
• Configure alerts for any unexpected SYSTEM-level process creation correlated with Zoom installer activity
• Audit and log all software installation activities in enterprise environments

How to Mitigate CVE-2023-22883

Immediate Actions Required

• Upgrade Zoom Client for IT Admin Windows installers to version 5.13.5 or later immediately
• Restrict local user permissions during software installation operations where possible
• Implement application whitelisting to prevent unauthorized executables from running during installation processes
• Audit systems for any indicators of prior exploitation attempts

Patch Information

Zoom has addressed this vulnerability in version 5.13.5 of the Zoom Client for IT Admin Windows installers. Organizations should update to this version or later to remediate the vulnerability. The patch information and security advisory are available from the Zoom Security Bulletin.

Workarounds

• Perform Zoom installations only on isolated systems where no untrusted local users have access
• Use dedicated installation accounts and restrict interactive logons during installation windows
• Monitor installation processes in real-time for any signs of race condition exploitation
• Consider deploying Zoom via enterprise deployment solutions that minimize local interaction during installation

# Verify installed Zoom version and update if necessary
# Check current Zoom version via registry
reg query "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall" /s | findstr /i "Zoom"

# Download and deploy updated Zoom installer (5.13.5 or later)
# Ensure installations occur in controlled environments with limited local user access