CVE-2021-30972: Apple macOS Privacy Bypass Vulnerability

CVE-2021-30972 Overview

CVE-2021-30972 is an authorization bypass vulnerability affecting Apple macOS and Mac OS X systems. The vulnerability allows a malicious application to bypass certain Privacy preferences, potentially exposing sensitive user data or enabling unauthorized access to protected resources. This issue stems from insufficient checks within the macOS privacy framework (CWE-863: Incorrect Authorization).

Critical Impact

A malicious application running on an affected system can circumvent macOS Privacy preferences, potentially accessing protected user data such as contacts, calendar, photos, or other sensitive information without explicit user consent.

Affected Products

• Apple Mac OS X 10.15.7 (prior to Security Update 2022-001 Catalina)
• Apple macOS Big Sur (prior to version 11.6.3)
• Apple macOS 12.0.0 and 12.0.1 (Monterey)

Discovery Timeline

• 2021-08-24 - CVE-2021-30972 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2021-30972

Vulnerability Analysis

This vulnerability exists due to incorrect authorization checks within the macOS privacy subsystem. The flaw enables applications to bypass Transparency, Consent, and Control (TCC) protections that normally guard access to sensitive user data and system resources.

macOS relies on TCC to manage application permissions for accessing protected resources like the camera, microphone, contacts, calendars, and files. When an application requests access to these resources, TCC should prompt the user for consent. However, CVE-2021-30972 allows malicious applications to circumvent these checks entirely, accessing protected data without triggering the normal authorization prompts.

The vulnerability requires local access and a low-privileged user context to exploit. While no network-based attack vector exists, an attacker who can execute a malicious application on a target system—through phishing, supply chain compromise, or other means—could leverage this flaw to exfiltrate sensitive information.

Root Cause

The root cause is classified as CWE-863 (Incorrect Authorization), indicating that the affected macOS components failed to properly validate authorization requests. The privacy preference checks did not adequately verify that applications had received explicit user consent before granting access to protected resources. Apple addressed this by implementing improved checks to ensure proper authorization validation.

Attack Vector

Exploitation requires local access to an affected macOS system. An attacker must first gain the ability to execute code on the target, typically through:

1. Convincing a user to download and run a malicious application
2. Compromising a legitimate application that the user trusts
3. Exploiting another vulnerability to gain initial code execution

Once running on the system, the malicious application can bypass TCC privacy preferences to access sensitive data without user interaction or consent. The attack does not require elevated privileges, making it accessible to standard user-level malware.

Since no verified proof-of-concept code is publicly available, the specific technical mechanism involves manipulating how applications interact with the TCC database or related privacy frameworks to bypass authorization checks. For detailed technical information, refer to Apple's Security Update HT213055.

Detection Methods for CVE-2021-30972

Indicators of Compromise

• Unexpected applications appearing in System Preferences > Security & Privacy with access to protected resources
• Unauthorized access logs showing applications reading from protected directories (~/Library/Calendars, ~/Library/Contacts, etc.)
• Anomalous TCC database modifications in /Library/Application Support/com.apple.TCC/TCC.db

Detection Strategies

• Monitor for applications accessing TCC-protected resources without corresponding user consent events in system logs
• Implement endpoint detection rules for unusual access patterns to sensitive user data directories
• Deploy behavioral analysis to identify applications reading protected data immediately after installation without user prompts
• Audit TCC database entries for unauthorized permission grants

Monitoring Recommendations

• Enable unified logging for privacy-related events using log show --predicate 'subsystem == "com.apple.TCC"'
• Configure SentinelOne to monitor for suspicious application behavior targeting TCC-protected resources
• Establish baselines for normal application permission requests and alert on deviations

How to Mitigate CVE-2021-30972

Immediate Actions Required

• Update macOS Big Sur systems to version 11.6.3 or later immediately
• Apply Security Update 2022-001 Catalina for Mac OS X 10.15.7 systems
• Review currently installed applications and remove any untrusted software
• Audit System Preferences > Security & Privacy > Privacy to verify application permissions

Patch Information

Apple has released patches addressing this vulnerability. System administrators should apply the appropriate updates based on their macOS version:

• macOS Catalina: Security Update 2022-001 Catalina (HT213055)
• macOS Big Sur: macOS Big Sur 11.6.3 (HT213056)

Updates can be applied through System Preferences > Software Update or via managed deployment tools like Jamf or Munki for enterprise environments.

Workarounds

• Restrict application installations to Apple-notarized software only by enabling Gatekeeper (spctl --master-enable)
• Implement application whitelisting to prevent unauthorized software execution
• Configure endpoint protection solutions like SentinelOne to detect and block applications exhibiting privacy bypass behaviors
• Regularly review and revoke unnecessary application permissions in Security & Privacy preferences

# Configuration example
# Verify Gatekeeper is enabled (restricts apps to notarized software)
spctl --status

# Enable Gatekeeper if disabled
sudo spctl --master-enable

# Check current TCC permissions (requires Full Disk Access)
sudo sqlite3 /Library/Application\ Support/com.apple.TCC/TCC.db "SELECT client, service FROM access;"

# Remove all TCC permissions for a suspicious application
tccutil reset All com.suspicious.app.bundle.id