CVE-2020-9897
📋 TL;DR
This vulnerability allows arbitrary code execution through malicious PDF files due to an out-of-bounds write in Apple's PDF processing. It affects iOS, iPadOS, and macOS systems running vulnerable versions. Attackers can exploit this by tricking users into opening specially crafted PDF documents.
💻 Affected Systems
- iOS
- iPadOS
- macOS
📦 What is this software?
Ipados by Apple
Macos by Apple
macOS is Apple's desktop and laptop operating system powering Mac computers used by millions of professionals, developers, creative professionals, and enterprise users worldwide. Built on a Unix foundation with the Darwin kernel and modern Cocoa frameworks, macOS delivers a seamless ecosystem integr...
Learn more about Macos →⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with attacker gaining full control of the device, enabling data theft, surveillance, or ransomware deployment.
Likely Case
Malware installation leading to data exfiltration, credential theft, or device enrollment in botnets.
If Mitigated
Limited impact with proper sandboxing and privilege separation, potentially containing the exploit to the PDF viewer process.
🎯 Exploit Status
Exploitation requires user interaction to open a malicious PDF, but no authentication is needed once the file is opened.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: iOS 14.2, iPadOS 14.2, macOS Big Sur 11.0.1
Vendor Advisory: https://support.apple.com/en-us/HT211929
Restart Required: Yes
Instructions:
1. Go to Settings > General > Software Update on iOS/iPadOS or System Preferences > Software Update on macOS. 2. Download and install the available update. 3. Restart the device when prompted.
🔧 Temporary Workarounds
Disable PDF preview in email clients
allConfigure email clients to not automatically preview PDF attachments
Use alternative PDF viewers
macOSSet third-party PDF applications as default to bypass the vulnerable system component
🧯 If You Can't Patch
- Block PDF files at network perimeter or email gateways
- Implement application allowlisting to restrict PDF opening to trusted applications only
🔍 How to Verify
Check if Vulnerable:
Check system version: iOS/iPadOS: Settings > General > About > Version; macOS: Apple menu > About This MacCheck Version:
sw_vers (macOS) or system_profiler SPSoftwareDataType (macOS)Verify Fix Applied:
Verify version is iOS 14.2+, iPadOS 14.2+, or macOS 11.0.1+📡 Detection & Monitoring
Log Indicators:
- Unexpected crashes of Preview or PDF-related processes
- Suspicious file downloads with .pdf extension
Network Indicators:
- Unusual outbound connections after PDF file opening
- Downloads of PDF files from suspicious sources
SIEM Query:
source="apple_system_logs" AND (process="Preview" OR process="PDF") AND event="crash"