CVE-2021-40765
📋 TL;DR
Adobe Character Animator versions 4.4 and earlier contain a memory corruption vulnerability when parsing M4A audio files. This could allow attackers to execute arbitrary code with the privileges of the current user. Exploitation requires user interaction, such as opening a malicious M4A file.
💻 Affected Systems
- Adobe Character Animator
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise through arbitrary code execution, potentially leading to data theft, ransomware deployment, or persistent backdoor installation.
Likely Case
Local privilege escalation leading to user account compromise, data exfiltration, or malware installation.
If Mitigated
Limited impact due to user interaction requirement and proper security controls like application sandboxing and least privilege.
🎯 Exploit Status
Exploitation requires user interaction to open malicious M4A file. No public exploit code has been disclosed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 4.4.1 or later
Vendor Advisory: https://helpx.adobe.com/security/products/character_animator/apsb21-95.html
Restart Required: Yes
Instructions:
1. Open Adobe Character Animator. 2. Go to Help > Check for Updates. 3. Install update to version 4.4.1 or later. 4. Restart the application.
🔧 Temporary Workarounds
Disable M4A file association
allPrevent Character Animator from automatically opening M4A files
Windows: Use Default Programs settings to change M4A file association
macOS: Use Get Info on M4A files to change default application
User awareness training
allEducate users not to open M4A files from untrusted sources
🧯 If You Can't Patch
- Restrict user permissions to limit impact of successful exploitation
- Implement application whitelisting to prevent unauthorized code execution
🔍 How to Verify
Check if Vulnerable:
Check Adobe Character Animator version in Help > About Character AnimatorCheck Version:
Windows: Check program version in Control Panel > Programs and Features. macOS: Select Adobe Character Animator > Get InfoVerify Fix Applied:
Verify version is 4.4.1 or later in Help > About Character Animator📡 Detection & Monitoring
Log Indicators:
- Application crashes when processing M4A files
- Unexpected process creation from Character Animator
Network Indicators:
- Outbound connections from Character Animator to unexpected destinations
SIEM Query:
Process creation where parent process contains 'Character Animator' AND command line contains '.m4a'