CVE-2021-30809
📋 TL;DR
CVE-2021-30809 is a use-after-free vulnerability in Apple's WebKit browser engine that allows arbitrary code execution when processing malicious web content. It affects Safari, iOS, iPadOS, tvOS, and watchOS. Attackers can exploit this by tricking users into visiting specially crafted websites.
💻 Affected Systems
- Safari
- iOS
- iPadOS
- tvOS
- watchOS
📦 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 →Safari by Apple
Tvos by Apple
Watchos by Apple
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise with attacker gaining complete control over the device, enabling data theft, surveillance, or ransomware deployment.
Likely Case
Malicious website executes arbitrary code in browser context, potentially stealing cookies, session tokens, or installing malware.
If Mitigated
With proper patching and security controls, impact is limited to isolated browser process compromise that can be contained.
🎯 Exploit Status
Exploitation requires user interaction (visiting malicious website) but no authentication. Public references suggest exploit details are available.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Safari 15, iOS 15, iPadOS 15, tvOS 15, watchOS 8
Vendor Advisory: https://support.apple.com/en-us/HT212814
Restart Required: Yes
Instructions:
1. Update Safari to version 15 or later. 2. Update iOS/iPadOS to version 15 or later. 3. Update tvOS to version 15 or later. 4. Update watchOS to version 8 or later. 5. Restart device after update.
🔧 Temporary Workarounds
Disable JavaScript
allTemporarily disable JavaScript in Safari settings to prevent exploitation through malicious web content.
Use Alternative Browser
allSwitch to non-WebKit based browsers like Firefox or Chrome until patched.
🧯 If You Can't Patch
- Implement network filtering to block known malicious websites and restrict web browsing to trusted sites only.
- Enable application sandboxing and least privilege controls to limit potential damage from successful exploitation.
🔍 How to Verify
Check if Vulnerable:
Check Safari version (Safari > About Safari) or device OS version in Settings > General > About.Check Version:
On macOS: 'defaults read /Applications/Safari.app/Contents/Info.plist CFBundleShortVersionString'Verify Fix Applied:
Confirm Safari version is 15.0 or higher, or device OS is iOS 15+, iPadOS 15+, tvOS 15+, or watchOS 8+.📡 Detection & Monitoring
Log Indicators:
- Safari/WebKit crash logs with memory access violations
- Unexpected process termination of Safari or WebKit processes
Network Indicators:
- Connections to suspicious domains with unusual JavaScript payloads
- HTTP requests with crafted WebKit-specific parameters
SIEM Query:
source="safari.logs" AND (event="crash" OR event="memory_violation") AND process="WebKit"🔗 References
- http://www.openwall.com/lists/oss-security/2021/12/20/6
- https://support.apple.com/en-us/HT212814
- https://support.apple.com/en-us/HT212815
- https://support.apple.com/en-us/HT212816
- https://support.apple.com/en-us/HT212819
- https://support.apple.com/kb/HT212869
- http://www.openwall.com/lists/oss-security/2021/12/20/6
- https://support.apple.com/en-us/HT212814
- https://support.apple.com/en-us/HT212815
- https://support.apple.com/en-us/HT212816
- https://support.apple.com/en-us/HT212819
- https://support.apple.com/kb/HT212869
