Vulnerability identifier: #VU34141

Vulnerability risk: Low

CVSSv3.1: 5.8 [CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2019-20908

CWE-ID: CWE-276

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
Linux kernel
Operating systems & Components / Operating system

Vendor: Linux Foundation

Description

The vulnerability allows a local privileged user to execute arbitrary code.

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.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Linux kernel: 5.0 - 5.0.21, 5.1 - 5.1.21, 5.2 - 5.2.21, 5.3 - 5.3.18

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External links
http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00009.html
http://www.openwall.com/lists/oss-security/2020/07/20/6
http://www.openwall.com/lists/oss-security/2020/07/29/3
http://www.openwall.com/lists/oss-security/2020/07/30/2
http://www.openwall.com/lists/oss-security/2020/07/30/3
http://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.4
http://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=1957a85b0032a81e6482ca4aab883643b8dae06e
http://git.zx2c4.com/american-unsigned-language/tree/american-unsigned-language.sh
http://mailarchives.bentasker.co.uk/Mirrors/OSSSec/2020/06-Jun/msg00035.html
http://usn.ubuntu.com/4426-1/
http://usn.ubuntu.com/4427-1/
http://usn.ubuntu.com/4439-1/
http://usn.ubuntu.com/4440-1/

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Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.