CVE-2020-3751
📋 TL;DR
This CVE describes a use-after-free vulnerability in Adobe Acrobat and Reader that could allow attackers to execute arbitrary code on affected systems. Users running vulnerable versions of Adobe Acrobat or Reader are at risk when opening malicious PDF files. The vulnerability affects multiple versions across different release tracks.
💻 Affected Systems
- Adobe Acrobat DC
- Adobe Acrobat Reader DC
- Adobe Acrobat 2017
- Adobe Acrobat Reader 2017
- Adobe Acrobat 2015
- Adobe Acrobat Reader 2015
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise through arbitrary code execution with the privileges of the current user, potentially leading to data theft, ransomware deployment, or lateral movement within networks.
Likely Case
Attackers deliver malicious PDF files via phishing emails or compromised websites, leading to malware installation or credential theft when users open the files.
If Mitigated
With proper security controls like application whitelisting, least privilege accounts, and network segmentation, impact is limited to isolated systems without critical data access.
🎯 Exploit Status
Exploitation requires user interaction to open a malicious PDF file. While no public proof-of-concept exists, use-after-free vulnerabilities in PDF readers are commonly exploited in targeted attacks.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Acrobat DC/Reader DC: 2020.001.20035 or later; Acrobat 2017/Reader 2017: 2017.011.30166 or later; Acrobat 2015/Reader 2015: 2015.006.30518 or later
Vendor Advisory: https://helpx.adobe.com/security/products/acrobat/apsb20-05.html
Restart Required: Yes
Instructions:
1. Open Adobe Acrobat or Reader. 2. Go to Help > Check for Updates. 3. Follow prompts to download and install available updates. 4. Restart the application when prompted. 5. Verify the update by checking Help > About Adobe Acrobat/Reader.
🔧 Temporary Workarounds
Disable JavaScript in Adobe Reader
allDisabling JavaScript reduces attack surface as many PDF exploits rely on JavaScript execution.
Edit > Preferences > JavaScript > Uncheck 'Enable Acrobat JavaScript'
Use Protected View
allEnable Protected View for files from potentially unsafe locations to limit code execution.
Edit > Preferences > Security (Enhanced) > Enable Protected View at startup
🧯 If You Can't Patch
- Implement application control policies to block execution of Adobe Reader/Acrobat from untrusted locations
- Use alternative PDF viewers for opening files from untrusted sources
🔍 How to Verify
Check if Vulnerable:
Check Adobe Acrobat/Reader version via Help > About Adobe Acrobat/Reader and compare against affected version ranges.Check Version:
On Windows: wmic product where "name like 'Adobe Acrobat%' or name like 'Adobe Reader%'" get name, versionVerify Fix Applied:
Verify version is updated to patched versions: DC/Reader DC 2020.001.20035+, 2017/Reader 2017 2017.011.30166+, or 2015/Reader 2015 2015.006.30518+.📡 Detection & Monitoring
Log Indicators:
- Application crashes of Adobe Acrobat/Reader with unusual memory addresses
- Process creation from Adobe Acrobat/Reader with unusual parent-child relationships
- Unusual network connections originating from Adobe processes
Network Indicators:
- Outbound connections from Adobe processes to suspicious IPs or domains
- DNS queries for known exploit kit domains following PDF file access
SIEM Query:
source="*adobe*" AND (event_type="process_creation" OR event_type="application_crash") AND (process_name="AcroRd32.exe" OR process_name="Acrobat.exe")