CVE-2021-1853
📋 TL;DR
CVE-2021-1853 is a local privilege escalation vulnerability in macOS that allows an attacker with local access to gain elevated system privileges. This affects macOS systems prior to Big Sur 11.3. The vulnerability stems from improper state management that can be exploited to bypass security restrictions.
💻 Affected Systems
- macOS
📦 What is this software?
Macos by Apple
macOS is Apple's desktop and laptop operating system powering Mac computers used by millions of professionals, developers, creative professionals, and enterprise users worldwide. Built on a Unix foundation with the Darwin kernel and modern Cocoa frameworks, macOS delivers a seamless ecosystem integr...
Learn more about Macos →⚠️ Risk & Real-World Impact
Worst Case
An attacker gains full root access to the system, enabling complete compromise, data theft, persistence mechanisms, and lateral movement within the network.
Likely Case
Local users or malware with initial access escalate privileges to install persistent backdoors, access sensitive files, or bypass security controls.
If Mitigated
With proper patch management and least privilege principles, impact is limited to isolated systems where attackers already have local access.
🎯 Exploit Status
Exploitation requires local access and knowledge of the logic flaw. No public exploit code has been released as of analysis.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: macOS Big Sur 11.3 and later
Vendor Advisory: https://support.apple.com/en-us/HT212325
Restart Required: Yes
Instructions:
1. Open System Preferences > Software Update. 2. Install macOS Big Sur 11.3 or later update. 3. Restart the system when prompted.
🔧 Temporary Workarounds
No effective workarounds
allThis is a core operating system vulnerability requiring patching. No configuration changes or workarounds can mitigate the privilege escalation.
🧯 If You Can't Patch
- Restrict local user access to vulnerable systems through strict access controls
- Implement application allowlisting to prevent execution of unauthorized binaries
🔍 How to Verify
Check if Vulnerable:
Check macOS version: if running macOS Big Sur earlier than version 11.3, the system is vulnerable.Check Version:
sw_versVerify Fix Applied:
Verify macOS version is 11.3 or higher via System Information or terminal command.📡 Detection & Monitoring
Log Indicators:
- Unusual privilege escalation events in system logs
- Unexpected root process execution from non-privileged users
Network Indicators:
- No network indicators as this is local exploitation
SIEM Query:
source="macos_system_logs" AND (event="privilege_escalation" OR process="sudo" OR user="root") AND user!="authorized_user"