CVE-2024-34331: Parallels Desktop Privilege Escalation

CVE-2024-34331 Overview

CVE-2024-34331 is a privilege escalation vulnerability affecting Parallels Desktop for Mac versions 19.3.0 and below. The vulnerability stems from a lack of code signature verification in the Parallels Service component, which runs as a setuid root binary. Attackers can exploit this flaw by crafting a malicious macOS installer that bypasses signature validation, allowing them to escalate privileges to root on the target system.

Critical Impact

This vulnerability enables complete system compromise through privilege escalation to root, allowing attackers to gain full administrative control over macOS systems running vulnerable versions of Parallels Desktop.

Affected Products

• Parallels Desktop for Mac v19.3.0 and below
• Parallels Service (setuid root component)
• macOS systems with Parallels Desktop installed

Discovery Timeline

• 2024-09-23 - CVE-2024-34331 published to NVD
• 2024-09-26 - Last updated in NVD database

Technical Details for CVE-2024-34331

Vulnerability Analysis

This vulnerability exists due to improper privilege management (CWE-269) in the Parallels Service component. The Parallels Service is configured with the setuid root bit, meaning it executes with root-level privileges regardless of the user invoking it. Under normal operation, this elevated privilege is necessary for the service to perform system-level operations required for virtualization.

The core issue is that Parallels Service fails to properly verify code signatures before executing installer packages. When processing macOS installers, the service does not validate that the installer has been signed by a trusted authority (such as Parallels or Apple). This oversight allows an attacker to craft a malicious installer package that, when processed by the Parallels Service, executes arbitrary code with root privileges.

Root Cause

The root cause of CVE-2024-34331 is the absence of code signature verification in the Parallels Service component. macOS provides robust code signing infrastructure through the Security framework and codesign utilities, but the Parallels Service fails to leverage these mechanisms when handling installer packages. Because the service operates with setuid root privileges, any code executed through the unverified installer path inherits full root access.

Attack Vector

An attacker can exploit this vulnerability by creating a specially crafted macOS installer package designed to be processed by the Parallels Service. The attack flow involves:

1. The attacker creates a malicious macOS installer package containing arbitrary payload code
2. The attacker either delivers this installer to the victim through social engineering or places it on a system where Parallels Desktop is installed
3. When the Parallels Service processes the installer, it fails to verify the code signature
4. The malicious payload executes with root privileges inherited from the setuid Parallels Service binary
5. The attacker achieves full privilege escalation, gaining complete control over the macOS system

The vulnerability is particularly dangerous because it bypasses macOS security mechanisms that normally prevent unauthorized privilege escalation. For detailed technical analysis of the exploitation mechanism, see the KhronoKernel CVE Analysis.

Detection Methods for CVE-2024-34331

Indicators of Compromise

• Unexpected installer packages being processed by Parallels Service
• Unsigned or improperly signed macOS installers in system or user directories
• Unusual root-level process spawning from Parallels Service components
• Suspicious modifications to system files or configurations following Parallels Desktop usage

Detection Strategies

• Monitor process execution chains originating from Parallels Service for anomalous child processes
• Implement file integrity monitoring on Parallels Desktop installation directories
• Use endpoint detection tools to flag unsigned installer packages being executed with elevated privileges
• Review system logs for privilege escalation attempts associated with Parallels components

Monitoring Recommendations

• Enable detailed logging for setuid binary executions on macOS systems
• Configure security information and event management (SIEM) rules to alert on unexpected root-level activity from virtualization software
• Implement application allowlisting to restrict installer execution to verified sources
• Deploy behavioral analysis to detect privilege escalation patterns consistent with this vulnerability

How to Mitigate CVE-2024-34331

Immediate Actions Required

• Update Parallels Desktop to the latest version immediately
• Review and audit any recently installed packages on systems running vulnerable Parallels Desktop versions
• Restrict user access to installer execution on critical systems
• Implement application control policies to prevent execution of unsigned installers

Patch Information

Parallels has addressed this vulnerability in versions released after v19.3.0. Administrators should update to the latest available version of Parallels Desktop for Mac. For specific patch information and upgrade instructions, refer to the Parallels Knowledge Base Article.

Workarounds

• Temporarily disable or remove Parallels Desktop from high-security systems until patches can be applied
• Implement strict application control policies that prevent execution of unsigned macOS installer packages
• Use macOS Gatekeeper and XProtect settings at maximum enforcement levels
• Consider using a dedicated, isolated virtual machine for running Parallels until the system is patched

# Verify Parallels Desktop version and check for available updates
/Applications/Parallels\ Desktop.app/Contents/MacOS/prlctl --version

# Check current Gatekeeper status
spctl --status

# Enable Gatekeeper if disabled (requires admin privileges)
sudo spctl --master-enable