CVE-2023-42856 – This is a memory corruption vulnerability in ma... (How to Fix)

Q: What is the severity of CVE-2023-42856?

CVE-2023-42856 has a CVSS score of 7.8 (HIGH). This is a memory corruption vulnerability in macOS that could allow arbitrary code execution or application crashes when processing malicious files. It affects macOS Monterey, Ventura, and Sonoma users who open untrusted files. The vulnerability stems from improper memory handling (CWE-119).

📋 TL;DR

This is a memory corruption vulnerability in macOS that could allow arbitrary code execution or application crashes when processing malicious files. It affects macOS Monterey, Ventura, and Sonoma users who open untrusted files. The vulnerability stems from improper memory handling (CWE-119).

💻 Affected Systems

Products:

macOS

Versions: macOS Monterey before 12.7.1, macOS Ventura before 13.6.1, macOS Sonoma before 14.1

Operating Systems: macOS

Default Config Vulnerable: ⚠️ Yes

Notes: All standard macOS installations with affected versions are vulnerable when processing files through vulnerable components.

📦 What is this software?

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 →

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 →

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

Remote code execution with the privileges of the user opening the malicious file, potentially leading to full system compromise.

🟠

Likely Case

Application crashes (denial of service) when processing specially crafted files, with code execution being possible but requiring more specific conditions.

🟢

If Mitigated

Limited to denial of service if exploit attempts are blocked by security controls or fail due to memory protections.

🌐 Internet-Facing: MEDIUM - Exploitation requires user interaction (opening a file), but malicious files could be delivered via email, downloads, or web links.

🏢 Internal Only: LOW - Primarily requires user interaction with malicious files, which is less common in controlled internal environments.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Exploitation requires user interaction to open a malicious file. No public proof-of-concept has been disclosed, but the vulnerability is memory corruption-based which often leads to weaponization.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: macOS Monterey 12.7.1, macOS Ventura 13.6.1, macOS Sonoma 14.1

Vendor Advisory: https://support.apple.com/en-us/HT213983

Restart Required: Yes

Instructions:

1. Open System Settings. 2. Click General. 3. Click Software Update. 4. Install available updates. 5. Restart when prompted.

🔧 Temporary Workarounds

Restrict file processing

all

Limit processing of untrusted files by using application sandboxing or restricting file types.

🧯 If You Can't Patch

Implement application allowlisting to restrict which applications can open files.
Use network filtering to block downloads of suspicious file types and educate users about opening untrusted files.

🔍 How to Verify

Check if Vulnerable:

Check macOS version in System Settings > General > About. If version is Monterey <12.7.1, Ventura <13.6.1, or Sonoma <14.1, the system is vulnerable.

Check Version:

sw_vers

Verify Fix Applied:

Verify macOS version is Monterey 12.7.1, Ventura 13.6.1, or Sonoma 14.1 or later in System Settings > General > About.

📡 Detection & Monitoring

Log Indicators:

Application crash logs (Console.app) showing unexpected termination during file processing
Security logs showing file access from untrusted sources

Network Indicators:

Unusual outbound connections following file processing
Downloads of suspicious file types

SIEM Query:

source="macOS" AND (event_type="crash" OR process="kernel") AND message="unexpected termination"

📊 Metadata

CVE ID: CVE-2023-42856

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-119

Published: October 25, 2023

Last Updated: November 21, 2024

🔗 References

http://seclists.org/fulldisclosure/2023/Oct/21 Mailing List,Third Party Advisory
http://seclists.org/fulldisclosure/2023/Oct/24 Mailing List,Third Party Advisory
http://seclists.org/fulldisclosure/2023/Oct/26 Mailing List,Third Party Advisory
https://support.apple.com/en-us/HT213983 Release Notes,Vendor Advisory
https://support.apple.com/en-us/HT213984 Release Notes,Vendor Advisory
https://support.apple.com/en-us/HT213985 Release Notes,Vendor Advisory
https://support.apple.com/kb/HT213983 Release Notes,Vendor Advisory
https://support.apple.com/kb/HT213984 Release Notes,Vendor Advisory
https://support.apple.com/kb/HT213985 Release Notes,Vendor Advisory
http://seclists.org/fulldisclosure/2023/Oct/21 Mailing List,Third Party Advisory
http://seclists.org/fulldisclosure/2023/Oct/24 Mailing List,Third Party Advisory
http://seclists.org/fulldisclosure/2023/Oct/26 Mailing List,Third Party Advisory
https://support.apple.com/en-us/HT213983 Release Notes,Vendor Advisory
https://support.apple.com/en-us/HT213984 Release Notes,Vendor Advisory
https://support.apple.com/en-us/HT213985 Release Notes,Vendor Advisory
https://support.apple.com/kb/HT213983 Release Notes,Vendor Advisory
https://support.apple.com/kb/HT213984 Release Notes,Vendor Advisory
https://support.apple.com/kb/HT213985 Release Notes,Vendor Advisory

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🔗 Related Vulnerabilities

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