CVE-2023-34195 – This vulnerability allows arbitrary code execut... (How to Fix)

Q: What is the severity of CVE-2023-34195?

CVE-2023-34195 has a CVSS score of 7.8 (HIGH). This vulnerability allows arbitrary code execution during the DXE phase of UEFI boot process in InsydeH2O firmware. Attackers can set a UEFI variable from the operating system to point to malicious code, bypassing chipset security locks. Systems using Insyde InsydeH2O firmware with kernel versions 5.0 through 5.5 are affected.

📋 TL;DR

This vulnerability allows arbitrary code execution during the DXE phase of UEFI boot process in InsydeH2O firmware. Attackers can set a UEFI variable from the operating system to point to malicious code, bypassing chipset security locks. Systems using Insyde InsydeH2O firmware with kernel versions 5.0 through 5.5 are affected.

💻 Affected Systems

Products:

Systems with Insyde InsydeH2O firmware

Versions: Kernel 5.0 through 5.5

Operating Systems: Any OS running on affected firmware (Windows, Linux, etc.)

Default Config Vulnerable: ⚠️ Yes

Notes: Affects various OEM systems using InsydeH2O firmware, including laptops, desktops, and embedded devices.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete system compromise with persistent firmware-level malware that survives OS reinstallation and disk replacement.

🟠

Likely Case

Privilege escalation from OS to firmware level, enabling persistent backdoors and bypassing security controls.

🟢

If Mitigated

Limited to local attackers with administrative privileges on the OS.

🌐 Internet-Facing: LOW - Requires local access or administrative privileges on the target system.

🏢 Internal Only: HIGH - Malicious insiders or compromised administrative accounts can exploit this for persistent access.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Requires administrative privileges on the OS to set UEFI variables. Exploitation occurs during boot process before chipset locks are enabled.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Check with OEM for specific firmware updates

Vendor Advisory: https://www.insyde.com/security-pledge/SA-2023052

Restart Required: Yes

Instructions:

1. Check with your device manufacturer for firmware updates. 2. Download and install the updated firmware from manufacturer's support site. 3. Follow manufacturer's instructions for firmware flashing. 4. Reboot system to apply changes.

🔧 Temporary Workarounds

Restrict UEFI variable access

all

Limit which users can modify UEFI runtime variables from the OS

Windows: Use Group Policy to restrict access to UEFI firmware settings
Linux: Configure kernel lockdown mode and restrict access to /sys/firmware/efi/efivars

🧯 If You Can't Patch

Implement strict access controls to prevent unauthorized users from gaining administrative privileges
Monitor for suspicious UEFI variable modifications and firmware access attempts

🔍 How to Verify

Check if Vulnerable:

Check firmware version in UEFI/BIOS settings or use manufacturer's diagnostic tools

Check Version:

Windows: wmic bios get smbiosbiosversion
Linux: dmidecode -s bios-version

Verify Fix Applied:

Verify firmware version has been updated beyond vulnerable versions in UEFI/BIOS settings

📡 Detection & Monitoring

Log Indicators:

UEFI variable modifications from OS
Firmware update events
Boot process anomalies

Network Indicators:

Unusual firmware update traffic
Communication with firmware management interfaces

SIEM Query:

EventID=1 OR EventID=12 AND (ProcessName="*firmware*" OR CommandLine="*UEFI*" OR CommandLine="*efi*")

📊 Metadata

CVE ID: CVE-2023-34195

CVSS v3 Score: 7.8 (HIGH)

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

CWE: CWE-94

Published: September 18, 2023

Last Updated: November 21, 2024

🔗 References

https://www.insyde.com/security-pledge Vendor Advisory
https://www.insyde.com/security-pledge/SA-2023052 Vendor Advisory
https://www.insyde.com/security-pledge Vendor Advisory
https://www.insyde.com/security-pledge/SA-2023052 Vendor Advisory

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🔗 Related Vulnerabilities

If you're affected by CVE-2023-34195, you might also want to check these:

📋 TL;DR

💻 Affected Systems

📦 What is this software?

Insydeh2o by Insyde

Insydeh2o by Insyde

Insydeh2o by Insyde

Insydeh2o by Insyde

Insydeh2o by Insyde

⚠️ Risk & Real-World Impact

Worst Case

Likely Case

If Mitigated

🎯 Exploit Status

🛠️ Fix & Mitigation

✅ Official Fix

Instructions:

🔧 Temporary Workarounds

Restrict UEFI variable access

🧯 If You Can't Patch

🔍 How to Verify

Check if Vulnerable:

Check Version:

Verify Fix Applied:

📡 Detection & Monitoring

Log Indicators:

Network Indicators:

SIEM Query:

📊 Metadata

🔗 References

📤 Share & Export

🔗 Related Vulnerabilities