CVE-2020-9604
📋 TL;DR
This CVE describes a buffer error 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, potentially leading to data theft, ransomware deployment, or persistent backdoor installation.
Likely Case
Local privilege escalation or remote code execution when a user opens a malicious PDF document, leading to malware installation or credential theft.
If Mitigated
Limited impact with proper application sandboxing and user privilege restrictions, potentially containing the exploit to the application context.
🎯 Exploit Status
Exploitation requires user interaction to open a malicious PDF file. No public exploit code was available at disclosure time, but buffer errors in PDF parsers are commonly targeted.
🛠️ 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 download and install available updates. 4. Restart the application when prompted. 5. Verify 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 for untrusted PDFs
allForce all PDFs from untrusted sources to open in Protected View mode.
Edit > Preferences > Security (Enhanced) > Check 'Enable Protected View at startup' and 'Enable Enhanced Security'
🧯 If You Can't Patch
- Restrict PDF file handling to alternative PDF viewers that are not vulnerable
- Implement application control policies to block execution of vulnerable Adobe versions
🔍 How to Verify
Check if Vulnerable:
Open Adobe Acrobat/Reader, go to Help > About Adobe Acrobat/Reader and compare version against affected ranges.Check Version:
On Windows: wmic product where name like "Adobe Acrobat%" get version; On macOS: /Applications/Adobe\ Acrobat*.app/Contents/Info.plist | grep -A1 CFBundleShortVersionStringVerify Fix Applied:
Verify version is at or above: DC: 2020.009.20063, 2017: 2017.011.30173, 2015: 2015.006.30523📡 Detection & Monitoring
Log Indicators:
- Application crashes in Adobe Acrobat/Reader with memory access violations
- Unexpected child processes spawned from AcroRd32.exe or AdobeReader.exe
Network Indicators:
- Outbound connections from Adobe processes to unexpected destinations following PDF opening
- DNS requests for suspicious domains from Adobe processes
SIEM Query:
process_name:("AcroRd32.exe" OR "AdobeReader.exe") AND (event_id:1000 OR event_id:1001) AND exception_code:(0xc0000005 OR 0xc0000409)