CVE-2021-31009 – This vulnerability involves multiple security i... (How to Fix)

Q: What is the severity of CVE-2021-31009?

CVE-2021-31009 has a CVSS score of 9.8 (CRITICAL). This vulnerability involves multiple security issues in the HDF5 library that could allow arbitrary code execution. Apple addressed these by completely removing HDF5 from affected systems. The vulnerability affects iOS, iPadOS, and macOS users running vulnerable versions.

📋 TL;DR

This vulnerability involves multiple security issues in the HDF5 library that could allow arbitrary code execution. Apple addressed these by completely removing HDF5 from affected systems. The vulnerability affects iOS, iPadOS, and macOS users running vulnerable versions.

💻 Affected Systems

Products:

iOS
iPadOS
macOS

Versions: Versions before iOS 15.2, iPadOS 15.2, and macOS Monterey 12.1

Operating Systems: iOS, iPadOS, macOS

Default Config Vulnerable: ⚠️ Yes

Notes: All default configurations are vulnerable. HDF5 was included by default in affected versions.

📦 What is this software?

Ipados by Apple

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Iphone Os by Apple

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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 attackers could execute arbitrary code with kernel privileges, potentially gaining full control over the device.

🟠

Likely Case

Attackers could execute arbitrary code with user privileges, leading to data theft, surveillance, or further system compromise.

🟢

If Mitigated

With proper network segmentation and least privilege, impact could be limited to isolated systems.

🌐 Internet-Facing: HIGH - Apple devices frequently connect to untrusted networks and download content.

🏢 Internal Only: MEDIUM - Internal exploitation would require initial access to the network.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ⚠️ Yes

Complexity: MEDIUM

CVSS 9.8 suggests network-accessible, unauthenticated exploitation is possible, but no public exploits have been confirmed.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: iOS 15.2, iPadOS 15.2, macOS Monterey 12.1

Vendor Advisory: https://support.apple.com/en-us/HT212976

Restart Required: Yes

Instructions:

1. Open Settings app. 2. Go to General > Software Update. 3. Install iOS 15.2/iPadOS 15.2 or macOS Monterey 12.1. 4. Restart device after installation.

🔧 Temporary Workarounds

Network segmentation

all

Restrict device network access to trusted sources only

Disable unnecessary services

all

Turn off services that might process HDF5 files

🧯 If You Can't Patch

Isolate affected devices from untrusted networks
Implement application allowlisting to prevent execution of unknown binaries

🔍 How to Verify

Check if Vulnerable:

Check Settings > General > About > Version. If version is earlier than iOS 15.2, iPadOS 15.2, or macOS Monterey 12.1, device is vulnerable.

Check Version:

sw_vers (macOS) or Settings > General > About > Version (iOS/iPadOS)

Verify Fix Applied:

Verify version shows iOS 15.2+, iPadOS 15.2+, or macOS Monterey 12.1+. Check that HDF5 libraries are no longer present.

📡 Detection & Monitoring

Log Indicators:

Unexpected process execution
HDF5 library loading attempts
Crash reports involving HDF5

Network Indicators:

Unexpected network connections after processing files
Downloads of HDF5 files from untrusted sources

SIEM Query:

Process execution containing 'hdf5' OR library load events for hdf5 files

📊 Metadata

CVE ID: CVE-2021-31009

CVSS v3 Score: 9.8 (CRITICAL)

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

Published: August 24, 2021

Last Updated: November 21, 2024

🔗 References

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