CVE-2021-39822
📋 TL;DR
Adobe InDesign has an out-of-bounds write vulnerability in BMP file parsing that allows arbitrary code execution when a user opens a malicious BMP file. This affects users running Adobe InDesign versions 16.3.1 and earlier. Successful exploitation requires user interaction to open a specially crafted BMP file.
💻 Affected Systems
- Adobe InDesign
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise with attacker gaining the same privileges as the current user, potentially leading to data theft, ransomware deployment, or lateral movement within the network.
Likely Case
Local privilege escalation leading to malware installation, data exfiltration, or persistence mechanisms being established on the affected system.
If Mitigated
Limited impact due to application sandboxing or restricted user privileges, potentially resulting in application crash rather than code execution.
🎯 Exploit Status
Exploitation requires user interaction to open malicious BMP file. No public exploit code has been disclosed as of knowledge cutoff.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 16.3.2 and later
Vendor Advisory: https://helpx.adobe.com/security/products/indesign/apsb21-73.html
Restart Required: Yes
Instructions:
1. Open Adobe InDesign. 2. Go to Help > Updates. 3. Install available updates to version 16.3.2 or later. 4. Restart the application.
🔧 Temporary Workarounds
Block BMP file extensions
allPrevent InDesign from opening BMP files via file extension blocking
Disable BMP file association
allRemove BMP file association with Adobe InDesign in operating system settings
🧯 If You Can't Patch
- Restrict user privileges to standard user accounts (not administrator)
- Implement application whitelisting to prevent execution of unauthorized code
🔍 How to Verify
Check if Vulnerable:
Check Adobe InDesign version via Help > About InDesign. If version is 16.3.1 or earlier, system is vulnerable.Check Version:
Not applicable - check via application GUIVerify Fix Applied:
Verify version is 16.3.2 or later via Help > About InDesign.📡 Detection & Monitoring
Log Indicators:
- Application crashes when opening BMP files
- Unusual process creation from InDesign
Network Indicators:
- Outbound connections from InDesign to unusual destinations
SIEM Query:
Process creation events where parent process is InDesign and command line contains suspicious parameters