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CVE-2018-18653

Publication date 25 October 2018

Last updated 24 July 2024

Ubuntu priority

Medium

Why this priority?

Cvss 3 Severity Score

7.8 · High

Score breakdown

The Linux kernel, as used in Ubuntu 18.10 and when booted with UEFI Secure Boot enabled, allows privileged local users to bypass intended Secure Boot restrictions and execute untrusted code by loading arbitrary kernel modules. This occurs because a modified kernel/module.c, in conjunction with certain configuration options, leads to mishandling of the result of signature verification.

From the Ubuntu Security Team

Daniel Dadap discovered that the module loading implementation in the Linux kernel did not properly enforce signed module loading when booted with UEFI Secure Boot in some situations. A local privileged attacker could use this to execute untrusted code in the kernel.

Read the notes from the security team

Status

Package Ubuntu Release Status
linux 18.10 cosmic
Fixed 4.18.0-12.13
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty
Not affected
linux-aws 18.10 cosmic
Fixed 4.18.0-1006.7
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty
Not affected
linux-aws-hwe 18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release
linux-azure 18.10 cosmic
Fixed 4.18.0-1006.6
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty
Not affected
linux-azure-edge 18.10 cosmic Not in release
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release
linux-euclid 18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Ignored
14.04 LTS trusty Not in release
linux-flo 18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Ignored
14.04 LTS trusty Not in release
linux-gcp 18.10 cosmic
Fixed 4.18.0-1004.5
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release
linux-gcp-edge 18.10 cosmic Not in release
18.04 LTS bionic
Not affected
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-gke 18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Ignored
14.04 LTS trusty Not in release
linux-goldfish 18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Ignored
14.04 LTS trusty Not in release
linux-grouper 18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-hwe 18.10 cosmic Not in release
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release
linux-hwe-edge 18.10 cosmic Not in release
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release
linux-kvm 18.10 cosmic
Fixed 4.18.0-1005.5
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release
linux-lts-trusty 18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-lts-utopic 18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-lts-vivid 18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-lts-wily 18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-lts-xenial 18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty
Not affected
linux-maguro 18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-mako 18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Ignored
14.04 LTS trusty Not in release
linux-manta 18.10 cosmic Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-oem 18.10 cosmic
Not affected
18.04 LTS bionic
Not affected
16.04 LTS xenial Ignored
14.04 LTS trusty Not in release
linux-oracle 18.10 cosmic
Not affected
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release
linux-raspi2 18.10 cosmic
Fixed 4.18.0-1007.9
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release
linux-snapdragon 18.10 cosmic Not in release
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release

Notes

sbeattie

from the commit addressing the issue: Recent versions of the "secure boot lockdown" patches introduced support for using IMA signatures for module signing instead of the standard mechanism. This was causing issues and was removed, but the code was missed which actually defers the verification to IMA when IMA enforcement is enabled. With our config this means that by default module signatures are not being enforced under kernel lockdown.

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package Patch details
linux

Severity score breakdown

Parameter Value
Base score 7.8 · High
Attack vector Local
Attack complexity Low
Privileges required Low
User interaction None
Scope Unchanged
Confidentiality High
Integrity impact High
Availability impact High
Vector CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

References

Related Ubuntu Security Notices (USN)

    • USN-3835-1
    • Linux kernel vulnerabilities
    • 3 December 2018
    • USN-3832-1
    • Linux kernel (AWS) vulnerabilities
    • 30 November 2018

Other references