CVE-2020-24435
📋 TL;DR
A heap-based buffer overflow vulnerability in Adobe Acrobat Reader DC's submitForm function allows arbitrary code execution when a user opens a malicious PDF file. This affects users running vulnerable versions of Acrobat Reader DC across multiple release tracks. Successful exploitation gives attackers the same privileges as the current user.
💻 Affected Systems
- Adobe Acrobat Reader DC
📦 What is this software?
Acrobat by Adobe
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with attacker gaining full control of the victim's machine, enabling data theft, ransomware deployment, or lateral movement within the network.
Likely Case
Malware installation leading to data exfiltration, credential theft, or system disruption, particularly in targeted attacks against organizations.
If Mitigated
Limited impact with proper security controls like application whitelisting, sandboxing, and least privilege user accounts preventing successful exploitation.
🎯 Exploit Status
Exploitation requires user interaction (opening a malicious PDF). No public exploit code was found in initial research, but heap overflow vulnerabilities are often weaponized.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2020.012.20056, 2020.001.30006, 2017.011.30176 or later
Vendor Advisory: https://helpx.adobe.com/security/products/acrobat/apsb20-67.html
Restart Required: Yes
Instructions:
1. Open Adobe Acrobat Reader DC. 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 by disabling JavaScript execution, which may be required for the submitForm vulnerability
Edit > Preferences > JavaScript > Uncheck 'Enable Acrobat JavaScript'
Use Protected View
allOpen PDFs in Protected View mode to restrict potentially dangerous operations
File > Open > Check 'Open in Protected View' or set as default in Preferences > Security (Enhanced)
🧯 If You Can't Patch
- Implement application whitelisting to block unauthorized PDF readers
- Use network segmentation to isolate PDF processing systems and restrict internet access
🔍 How to Verify
Check if Vulnerable:
Check Adobe Reader version via Help > About Adobe Acrobat Reader DC and compare with affected versionsCheck Version:
On Windows: wmic product where name="Adobe Acrobat Reader DC" get versionVerify Fix Applied:
Verify version is 2020.012.20056+, 2020.001.30006+, or 2017.011.30176+📡 Detection & Monitoring
Log Indicators:
- Adobe Reader crash logs with submitForm references
- Windows Event Logs showing Adobe Reader process termination
Network Indicators:
- Unusual outbound connections following PDF file opening
- DNS requests to suspicious domains after PDF access
SIEM Query:
source="*adobe*" AND (event_id=1000 OR event_id=1001) AND process_name="AcroRd32.exe"