CVE-2024-39804: Microsoft PowerPoint Auth Bypass Flaw

CVE-2024-39804 Overview

A library injection vulnerability exists in Microsoft PowerPoint 16.83 for macOS that allows attackers to leverage the application's access privileges, resulting in a permission bypass. This vulnerability enables a malicious application to inject a specially crafted library and start PowerPoint to trigger the vulnerability, subsequently abusing the vulnerable application's permissions on the system.

Critical Impact

This library injection flaw enables attackers to bypass macOS security controls by hijacking PowerPoint's elevated permissions, potentially gaining unauthorized access to protected system resources and sensitive data.

Affected Products

• Microsoft PowerPoint 16.83 for macOS
• Microsoft Office Suite for macOS (versions including PowerPoint 16.83)

Discovery Timeline

• 2024-12-18 - CVE-2024-39804 published to NVD
• 2025-08-25 - Last updated in NVD database

Technical Details for CVE-2024-39804

Vulnerability Analysis

This vulnerability stems from improper verification of cryptographic signatures (CWE-347) in Microsoft PowerPoint for macOS. The flaw allows an attacker to inject a malicious library into the PowerPoint process, which then executes with the application's elevated privileges. On macOS, applications like Microsoft PowerPoint are granted specific entitlements and permissions by the operating system, including access to protected resources such as the camera, microphone, files, and calendar.

When a malicious library is successfully injected, it inherits all of PowerPoint's permissions and entitlements. This effectively bypasses macOS's security model, which relies on per-application permission grants. The attacker can then leverage these inherited permissions to access protected resources without requiring explicit user consent.

Root Cause

The root cause of this vulnerability lies in insufficient validation of dynamically loaded libraries within Microsoft PowerPoint for macOS. The application fails to properly verify the cryptographic signatures of libraries before loading them into its process space. This improper verification allows unsigned or maliciously signed libraries to be loaded and executed within the context of a trusted, entitled application.

Attack Vector

The attack vector is network-based, requiring no privileges or user interaction according to the vulnerability characteristics. An attacker must first deliver a malicious library to the target system, which can be accomplished through various methods including phishing, malicious downloads, or other delivery mechanisms.

Once the malicious library is present on the system, the attack proceeds as follows:

1. The attacker positions a specially crafted dynamic library (dylib) in a location where PowerPoint will load it
2. The malicious application triggers PowerPoint to launch
3. PowerPoint loads the injected library without proper signature verification
4. The malicious code executes with PowerPoint's full permissions and entitlements
5. The attacker gains access to protected macOS resources through the hijacked permissions

This attack technique is particularly concerning on macOS because users explicitly grant applications permission to access sensitive resources like the camera, microphone, and files. By hijacking a trusted application like PowerPoint, attackers can silently abuse these granted permissions.

Detection Methods for CVE-2024-39804

Indicators of Compromise

• Unexpected dynamic libraries loaded into Microsoft PowerPoint processes
• Unusual child processes spawned from PowerPoint that access sensitive resources
• Modifications to library search paths or DYLD environment variables associated with Office applications
• Suspicious files with .dylib extension appearing in application bundle directories or library paths

Detection Strategies

• Monitor for unusual library loading events in Microsoft Office application processes using endpoint detection tools
• Implement code signing verification alerts for unsigned or invalidly signed libraries loaded by trusted applications
• Deploy behavioral analysis to detect Office applications accessing resources inconsistent with normal usage patterns
• Utilize macOS unified logging to track dyld library loading events for Office applications

Monitoring Recommendations

• Enable detailed process monitoring for all Microsoft Office applications on macOS endpoints
• Configure alerts for PowerPoint accessing sensitive resources (camera, microphone, contacts) outside of expected workflows
• Monitor for changes to environment variables like DYLD_INSERT_LIBRARIES that could facilitate library injection
• Review macOS TCC (Transparency, Consent, and Control) database access logs for anomalous permission usage

How to Mitigate CVE-2024-39804

Immediate Actions Required

• Update Microsoft PowerPoint for macOS to the latest available version from Microsoft
• Review and audit macOS application permissions granted to Microsoft Office applications
• Implement application whitelisting to prevent execution of unauthorized libraries
• Deploy endpoint protection solutions capable of detecting library injection attacks

Patch Information

Microsoft has been notified of this vulnerability through Cisco Talos' responsible disclosure process. Organizations should monitor Microsoft's security update releases and apply patches as soon as they become available. Refer to the Talos Intelligence Vulnerability Report for additional technical details and remediation guidance.

Workarounds

• Restrict execution of unsigned code on macOS systems using Gatekeeper policies
• Limit the permissions granted to Microsoft Office applications to only those strictly necessary for business operations
• Implement macOS System Integrity Protection (SIP) and ensure it remains enabled on all endpoints
• Use macOS sandboxing capabilities and MDM profiles to restrict Office application behaviors where possible

# Check Microsoft PowerPoint version on macOS
/Applications/Microsoft\ PowerPoint.app/Contents/MacOS/Microsoft\ PowerPoint --version

# Verify code signing of PowerPoint application
codesign -dv --verbose=4 /Applications/Microsoft\ PowerPoint.app

# List loaded libraries in running PowerPoint process (for investigation)
# Replace [PID] with actual process ID
vmmap [PID] | grep dylib