Linux Kernel up to 5.3 Lockdown/Secure Boot efi.c efivar_ssdt ACPI default permission

CVSS Meta Temp Score
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CTI Interest Score
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5.2$0-$5k0.00

Summaryinfo

A vulnerability marked as critical has been reported in Linux Kernel up to 5.3. This impacts the function efivar_ssdt of the file drivers/firmware/efi/efi.c of the component Lockdown/Secure Boot. The manipulation of the argument ACPI as part of Variable leads to default permission. This vulnerability is traded as CVE-2019-20908. An attack has to be approached locally. There is no exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Linux Kernel up to 5.3 (Operating System). This issue affects the function efivar_ssdt of the file drivers/firmware/efi/efi.c of the component Lockdown/Secure Boot. The manipulation of the argument ACPI as part of a Variable leads to a default permission vulnerability. Using CWE to declare the problem leads to CWE-276. During installation, installed file permissions are set to allow anyone to modify those files. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

An issue was discovered in drivers/firmware/efi/efi.c in the Linux kernel before 5.4. Incorrect access permissions for the efivar_ssdt ACPI variable could be used by attackers to bypass lockdown or secure boot restrictions, aka CID-1957a85b0032.

The weakness was shared 07/15/2020. The identification of this vulnerability is CVE-2019-20908 since 07/15/2020. Attacking locally is a requirement. No form of authentication is needed for a successful exploitation. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1222 according to MITRE ATT&CK.

Upgrading to version 5.4 eliminates this vulnerability.

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Productinfo

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Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.4
VulDB Meta Temp Score: 5.3

VulDB Base Score: 4.2
VulDB Temp Score: 4.0
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 6.7
NVD Vector: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

NVD Base Score: 🔍

Exploitinginfo

Class: Default permission
CWE: CWE-276 / CWE-266
CAPEC: 🔍
ATT&CK: 🔍

Physical: Partially
Local: Yes
Remote: No

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔍

Upgrade: Kernel 5.4

Timelineinfo

07/15/2020 🔍
07/15/2020 +0 days 🔍
07/16/2020 +1 days 🔍
07/16/2020 +0 days 🔍

Sourcesinfo

Vendor: kernel.org

Status: Not defined

CVE: CVE-2019-20908 (🔍)
GCVE (CVE): GCVE-0-2019-20908
GCVE (VulDB): GCVE-100-158519

Entryinfo

Created: 07/16/2020 10:51
Updated: 07/16/2020 10:56
Changes: 07/16/2020 10:51 (42), 07/16/2020 10:56 (18)
Complete: 🔍
Cache ID: 216::103

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