CVE-2020-9873 – This vulnerability allows arbitrary code execut... (How to Fix)

Q: What is the severity of CVE-2020-9873?

CVE-2020-9873 has a CVSS score of 7.8 (HIGH). This vulnerability allows arbitrary code execution when processing maliciously crafted images due to an out-of-bounds read. It affects multiple Apple operating systems and applications. Attackers can exploit this to run unauthorized code on affected devices.

📋 TL;DR

This vulnerability allows arbitrary code execution when processing maliciously crafted images due to an out-of-bounds read. It affects multiple Apple operating systems and applications. Attackers can exploit this to run unauthorized code on affected devices.

💻 Affected Systems

Products:

iOS
iPadOS
macOS Catalina
tvOS
watchOS
iTunes for Windows
iCloud for Windows

Versions: Versions prior to iOS 13.6, iPadOS 13.6, macOS Catalina 10.15.6, tvOS 13.4.8, watchOS 6.2.8, iTunes 12.10.8, iCloud for Windows 11.3/7.20

Operating Systems: iOS, iPadOS, macOS, tvOS, watchOS, Windows

Default Config Vulnerable: ⚠️ Yes

Notes: All default configurations are vulnerable. The vulnerability is triggered when processing malicious images through built-in image handling components.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Full system compromise with attacker gaining complete control over the device, potentially leading to data theft, ransomware deployment, or persistent backdoor installation.

🟠

Likely Case

Malicious image delivered via email, messaging, or web content triggers code execution, allowing attackers to steal sensitive data, install malware, or pivot to other systems.

🟢

If Mitigated

With proper patching and security controls, impact is limited to isolated incidents that can be quickly contained and remediated.

🌐 Internet-Facing: MEDIUM

🏢 Internal Only: MEDIUM

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ⚠️ Yes

Complexity: MEDIUM

Exploitation requires user interaction to process a malicious image, but no authentication is needed once the image is processed.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: iOS 13.6, iPadOS 13.6, macOS Catalina 10.15.6, tvOS 13.4.8, watchOS 6.2.8, iTunes 12.10.8, iCloud for Windows 11.3/7.20

Vendor Advisory: https://support.apple.com/kb/HT211288

Restart Required: Yes

Instructions:

1. Open Settings/System Preferences. 2. Navigate to Software Update. 3. Download and install the latest available update. 4. Restart the device when prompted.

🔧 Temporary Workarounds

Disable automatic image processing

all

Configure email clients and browsers to not automatically download or display images from untrusted sources.

Network filtering

all

Block image file types at network perimeter for untrusted sources.

🧯 If You Can't Patch

Implement strict email filtering to block suspicious image attachments
Deploy endpoint protection with memory protection capabilities

🔍 How to Verify

Check if Vulnerable:

Check current OS/application version against affected versions listed in Apple advisories.

Check Version:

iOS/iPadOS: Settings > General > About; macOS: Apple menu > About This Mac; Windows: Application Help > About

Verify Fix Applied:

Verify installed version matches or exceeds patched versions: iOS/iPadOS ≥13.6, macOS ≥10.15.6, tvOS ≥13.4.8, watchOS ≥6.2.8, iTunes ≥12.10.8, iCloud for Windows ≥11.3/7.20.

📡 Detection & Monitoring

Log Indicators:

Unexpected process crashes in image handling services
Memory access violation errors in system logs
Unusual image file processing from untrusted sources

Network Indicators:

Unusual outbound connections following image file downloads
Suspicious image file transfers from external sources

SIEM Query:

source="*system.log*" AND ("out of bounds" OR "memory violation" OR "segmentation fault") AND process="*image*"

📊 Metadata

CVE ID: CVE-2020-9873

CVSS v3 Score: 7.8 (HIGH)

CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CWE: CWE-125

Published: October 22, 2020

Last Updated: November 21, 2024

🔗 References

https://support.apple.com/kb/HT211288 Vendor Advisory
https://support.apple.com/kb/HT211289 Vendor Advisory
https://support.apple.com/kb/HT211290 Vendor Advisory
https://support.apple.com/kb/HT211291 Vendor Advisory
https://support.apple.com/kb/HT211293 Vendor Advisory
https://support.apple.com/kb/HT211294 Vendor Advisory
https://support.apple.com/kb/HT211295 Vendor Advisory
https://support.apple.com/kb/HT211288 Vendor Advisory
https://support.apple.com/kb/HT211289 Vendor Advisory
https://support.apple.com/kb/HT211290 Vendor Advisory
https://support.apple.com/kb/HT211291 Vendor Advisory
https://support.apple.com/kb/HT211293 Vendor Advisory
https://support.apple.com/kb/HT211294 Vendor Advisory
https://support.apple.com/kb/HT211295 Vendor Advisory

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🔗 Related Vulnerabilities

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