CVE-2024-39423
📋 TL;DR
This CVE describes an out-of-bounds write vulnerability in Adobe Acrobat Reader that could allow arbitrary code execution when a user opens a malicious PDF file. Attackers can exploit this to run code with the same privileges as the current user. All users running affected versions of Acrobat Reader are at risk.
💻 Affected Systems
- Adobe Acrobat Reader DC
- Adobe Acrobat Reader
📦 What is this software?
Acrobat by Adobe
Acrobat by Adobe
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with attacker gaining full control of the victim's computer, data theft, ransomware deployment, and lateral movement within the network.
Likely Case
Malware installation leading to data exfiltration, credential theft, or system disruption through targeted phishing campaigns with malicious PDF attachments.
If Mitigated
Limited impact with proper security controls - user account isolation prevents privilege escalation, application sandboxing contains the exploit, and endpoint protection blocks malicious files.
🎯 Exploit Status
Exploitation requires user interaction (opening malicious file). No public exploit code available at time of advisory.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Update to version 20.005.30637 or later for Acrobat Reader DC, or version 24.002.20966 or later for Acrobat Reader
Vendor Advisory: https://helpx.adobe.com/security/products/acrobat/apsb24-57.html
Restart Required: Yes
Instructions:
1. Open Adobe Acrobat Reader. 2. Go to Help > Check for Updates. 3. Follow prompts to download and install available updates. 4. Restart the application when prompted.
🔧 Temporary Workarounds
Disable JavaScript in Adobe Reader
allPrevents JavaScript-based exploitation vectors in PDF files
Edit > Preferences > JavaScript > Uncheck 'Enable Acrobat JavaScript'
Use Protected View
allOpen PDFs in Protected View mode to restrict file capabilities
File > Open > Select file > Check 'Open in Protected View'
🧯 If You Can't Patch
- Restrict PDF file handling to alternative PDF readers that are not vulnerable
- Implement application whitelisting to block execution of malicious code from Acrobat Reader
🔍 How to Verify
Check if Vulnerable:
Check Adobe Acrobat Reader version in Help > About Adobe Acrobat Reader DCCheck Version:
On Windows: wmic product where name="Adobe Acrobat Reader DC" get versionVerify Fix Applied:
Verify version is 20.005.30637 or later for Acrobat Reader DC, or 24.002.20966 or later for Acrobat Reader📡 Detection & Monitoring
Log Indicators:
- Acrobat Reader crash logs with memory access violations
- Windows Event Logs showing Acrobat process spawning unexpected child processes
Network Indicators:
- Outbound connections from Acrobat Reader process to suspicious IPs
- DNS requests for known malicious domains from Acrobat process
SIEM Query:
process_name:"AcroRd32.exe" AND (event_type:process_creation OR event_type:crash)