CVE-2019-20908 : Security Advisory and Response
Learn about CVE-2019-20908, a Linux kernel vulnerability allowing attackers to bypass security measures by manipulating access permissions. Find mitigation steps here.
A vulnerability was identified in the Linux kernel prior to version 5.4, specifically in the drivers/firmware/efi/efi.c file. Attackers could exploit this vulnerability by manipulating the access permissions of the efivar_ssdt ACPI variable, potentially bypassing lockdown or secure boot measures.
Understanding CVE-2019-20908
This CVE pertains to a security issue in the Linux kernel that could allow attackers to circumvent security measures.
What is CVE-2019-20908?
CVE-2019-20908 is a vulnerability in the Linux kernel that affects versions before 5.4. It involves incorrect access permissions for the efivar_ssdt ACPI variable, enabling potential bypass of lockdown or secure boot restrictions.
The Impact of CVE-2019-20908
The vulnerability could be exploited by attackers to bypass security measures, potentially compromising the integrity of the system and allowing unauthorized access.
Technical Details of CVE-2019-20908
This section provides more in-depth technical information about the CVE.
Vulnerability Description
The issue resides in drivers/firmware/efi/efi.c in the Linux kernel before version 5.4. Incorrect access permissions for the efivar_ssdt ACPI variable could be leveraged by attackers to bypass lockdown or secure boot restrictions.
Affected Systems and Versions
- Systems running Linux kernel versions prior to 5.4
Exploitation Mechanism
Attackers can exploit this vulnerability by manipulating the access permissions of the efivar_ssdt ACPI variable, potentially allowing them to bypass lockdown or secure boot measures.
Mitigation and Prevention
Protecting systems from CVE-2019-20908 requires immediate action and long-term security practices.
Immediate Steps to Take
- Update the Linux kernel to version 5.4 or newer to mitigate the vulnerability
- Monitor for any unauthorized changes to the efivar_ssdt ACPI variable
Long-Term Security Practices
- Implement secure boot configurations to prevent unauthorized modifications
- Regularly apply security patches and updates to the system
Patching and Updates
- Apply patches provided by the Linux kernel maintainers to address the vulnerability