CVE-2020-9843
📋 TL;DR
This CVE describes a cross-site scripting (XSS) vulnerability in Apple's web content processing across multiple platforms. Attackers can inject malicious scripts into web pages viewed by users, potentially stealing session cookies, credentials, or performing actions on behalf of the user. Affected users include anyone running vulnerable versions of iOS, iPadOS, tvOS, watchOS, Safari, iTunes for Windows, or iCloud for Windows.
💻 Affected Systems
- iOS
- iPadOS
- tvOS
- watchOS
- Safari
- iTunes for Windows
- iCloud for Windows
📦 What is this software?
Icloud by Apple
Icloud by Apple
Ipados by Apple
Itunes by Apple
Safari by Apple
Tvos by Apple
Watchos by Apple
⚠️ Risk & Real-World Impact
Worst Case
Complete account takeover, credential theft, session hijacking, and unauthorized actions performed on behalf of authenticated users across Apple services.
Likely Case
Session cookie theft leading to account compromise, credential harvesting via phishing, and limited unauthorized actions within web applications.
If Mitigated
Minimal impact with proper Content Security Policy headers, input validation, and output encoding in place.
🎯 Exploit Status
XSS vulnerabilities typically have low exploitation complexity once the specific input vector is identified. No public proof-of-concept has been disclosed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: iOS 13.5, iPadOS 13.5, tvOS 13.4.5, watchOS 6.2.5, Safari 13.1.1, iTunes 12.10.7 for Windows, iCloud for Windows 11.2, iCloud for Windows 7.19
Vendor Advisory: https://support.apple.com/HT211168
Restart Required: Yes
Instructions:
1. Open Settings app on Apple devices. 2. Navigate to General > Software Update. 3. Install available updates. 4. For Windows software, open the respective application and check for updates in Help menu or use Apple Software Update utility.
🔧 Temporary Workarounds
Enable Content Security Policy
allImplement strict Content Security Policy headers to restrict script execution from untrusted sources.
Content-Security-Policy: default-src 'self'; script-src 'self'
Disable JavaScript for Untrusted Sites
allConfigure browsers to disable JavaScript execution for untrusted or suspicious websites.
🧯 If You Can't Patch
- Implement web application firewalls (WAF) with XSS protection rules
- Use browser extensions that block malicious scripts and enforce strict CSP
🔍 How to Verify
Check if Vulnerable:
Check software version against affected versions list. On Apple devices: Settings > General > About > Version. On Windows: Help > About in respective applications.Check Version:
On macOS/Linux: sw_vers (for Safari), On Windows: wmic product get name,version | findstr /i "iTunes iCloud"Verify Fix Applied:
Confirm version matches or exceeds patched versions listed in vendor advisory.📡 Detection & Monitoring
Log Indicators:
- Unusual JavaScript execution patterns
- Suspicious script tags in web server logs
- Unexpected iframe or script injections
Network Indicators:
- Malicious script payloads in HTTP requests
- Suspicious redirects to external domains
- Unusual cookie access patterns
SIEM Query:
source="web_server" AND ("<script>" OR "javascript:" OR "onload=" OR "onerror=") AND status=200🔗 References
- https://support.apple.com/HT211168
- https://support.apple.com/HT211171
- https://support.apple.com/HT211175
- https://support.apple.com/HT211177
- https://support.apple.com/HT211178
- https://support.apple.com/HT211179
- https://support.apple.com/HT211181
- https://support.apple.com/HT211168
- https://support.apple.com/HT211171
- https://support.apple.com/HT211175
- https://support.apple.com/HT211177
- https://support.apple.com/HT211178
- https://support.apple.com/HT211179
- https://support.apple.com/HT211181
