CVE-2020-9594
📋 TL;DR
This CVE describes an out-of-bounds write 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 across multiple release tracks are at risk. Successful exploitation requires a user to open a malicious PDF file.
💻 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
Full system compromise with attacker gaining the same privileges as the user opening the malicious PDF, potentially leading to data theft, ransomware deployment, or persistent backdoor installation.
Likely Case
Local privilege escalation or remote code execution when users open malicious PDFs, leading to malware installation or credential theft.
If Mitigated
Limited impact with proper application sandboxing, minimal user privileges, and network segmentation preventing lateral movement.
🎯 Exploit Status
Exploitation requires user interaction (opening a malicious PDF). No public exploit code was available at disclosure time, but the vulnerability type suggests reliable exploitation is possible.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Acrobat DC/Reader DC: 2020.009.20063 or later; Acrobat 2017/Reader 2017: 2017.011.30173 or later; Acrobat 2015/Reader 2015: 2015.006.30523 or later
Vendor Advisory: https://helpx.adobe.com/security/products/acrobat/apsb20-24.html
Restart Required: Yes
Instructions:
1. Open Adobe Acrobat or Reader. 2. Go to Help > Check for Updates. 3. Follow prompts to install available updates. 4. Restart the application when prompted. Alternatively, download and install the latest version from Adobe's website.
🔧 Temporary Workarounds
Disable JavaScript in Adobe Reader
allPrevents JavaScript-based exploitation vectors that might be used to trigger this vulnerability
Edit > Preferences > JavaScript > Uncheck 'Enable Acrobat JavaScript'
Use Protected View
allOpens PDFs in sandboxed mode to limit potential damage
File > Properties > Security > Enable Protected View for all files
🧯 If You Can't Patch
- Restrict PDF file handling to trusted sources only
- Implement application whitelisting to prevent unauthorized code execution
🔍 How to Verify
Check if Vulnerable:
Check Adobe Acrobat/Reader version against affected ranges: Help > About Adobe Acrobat/ReaderCheck Version:
On Windows: wmic product where name like "Adobe Acrobat%" get version; On macOS: /Applications/Adobe\ Acrobat\ Reader\ DC.app/Contents/Info.plist | grep -A1 CFBundleShortVersionStringVerify Fix Applied:
Verify version is equal to or greater than patched versions: 2020.009.20063 (DC), 2017.011.30173 (2017), or 2015.006.30523 (2015)📡 Detection & Monitoring
Log Indicators:
- Unexpected process crashes of AcroRd32.exe or Acrobat.exe
- Suspicious child processes spawned from Adobe processes
- Unusual file writes or registry modifications by Adobe processes
Network Indicators:
- Unexpected outbound connections from Adobe processes
- DNS requests for known malicious domains following PDF opening
SIEM Query:
process_name:("AcroRd32.exe" OR "Acrobat.exe") AND (event_id:1000 OR event_id:1001) | where process_version < "2020.009.20063"