CVE-2023-26423
📋 TL;DR
Adobe Acrobat Reader versions 23.001.20093 and earlier, and 20.005.30441 and earlier, contain a use-after-free vulnerability that could allow an attacker to execute arbitrary code with the privileges of the current user. Exploitation requires the victim to open a malicious PDF file. This affects all users running vulnerable versions of Adobe Acrobat Reader.
💻 Affected Systems
- Adobe Acrobat Reader DC
- Adobe Acrobat Reader
📦 What is this software?
Acrobat by Adobe
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise with attacker gaining the same privileges as the logged-in user, potentially leading to data theft, ransomware deployment, or lateral movement within the network.
Likely Case
Local code execution allowing malware installation, credential theft, or data exfiltration from the affected system.
If Mitigated
No impact if proper patching and security controls are implemented, including application whitelisting and least privilege principles.
🎯 Exploit Status
Exploitation requires user interaction (opening malicious PDF). No public exploit code available at time of advisory.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 23.001.20174 (Continuous track), 20.005.30516 (Classic 2020 track)
Vendor Advisory: https://helpx.adobe.com/security/products/acrobat/apsb23-24.html
Restart Required: Yes
Instructions:
1. Open Adobe Acrobat Reader. 2. Go to Help > Check for Updates. 3. Follow prompts to install available updates. 4. Restart the application when prompted.
🔧 Temporary Workarounds
Disable JavaScript in Adobe Reader
allPrevents exploitation vectors that rely on JavaScript execution
Edit > Preferences > JavaScript > Uncheck 'Enable Acrobat JavaScript'
Enable Protected View for all files
allForces all PDFs to open in sandboxed Protected View mode
Edit > Preferences > Security (Enhanced) > Check 'Enable Protected View at startup' and 'Enable Enhanced Security'
🧯 If You Can't Patch
- Implement application control/whitelisting to block unauthorized PDF readers
- Use network segmentation to limit lateral movement from potentially compromised systems
🔍 How to Verify
Check if Vulnerable:
Check Adobe Acrobat Reader version via Help > About Adobe Acrobat Reader DCCheck Version:
Windows: "C:\Program Files\Adobe\Acrobat Reader DC\Reader\AcroRd32.exe" /? | findstr /i versionVerify Fix Applied:
Verify version is 23.001.20174 or higher (Continuous) or 20.005.30516 or higher (Classic 2020)📡 Detection & Monitoring
Log Indicators:
- Windows Event Logs: Application crashes (Event ID 1000) from AcroRd32.exe
- Process creation from Adobe Reader with unusual command-line arguments
Network Indicators:
- Outbound connections from Adobe Reader process to unknown IPs
- DNS queries for suspicious domains from systems running Adobe Reader
SIEM Query:
source="*windows*" event_id=1000 process_name="AcroRd32.exe" OR process_name="Acrobat.exe"