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Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS : Intel Microcode regression (USN-4385-2)

medium Nessus Plugin ID 137352

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Synopsis

The remote Ubuntu host is missing a security update.

Description

USN-4385-1 provided updated Intel Processor Microcode. Unfortunately, that update prevented certain processors in the Intel Skylake family (06_4EH) from booting successfully. Additonally, on Ubuntu 20.04 LTS, late loading of microcode was enabled, which could lead to system instability. This update reverts the microcode update for the Skylake processor family and disables the late loading option on Ubuntu 20.04 LTS.

Please note that the 'dis_ucode_ldr' kernel command line option can be added in the boot menu to disable microcode loading for system recovery.

We apologize for the inconvenience.

It was discovered that memory contents previously stored in microarchitectural special registers after RDRAND, RDSEED, and SGX EGETKEY read operations on Intel client and Xeon E3 processors may be briefly exposed to processes on the same or different processor cores.
A local attacker could use this to expose sensitive information.
(CVE-2020-0543)

It was discovered that on some Intel processors, partial data values previously read from a vector register on a physical core may be propagated into unused portions of the store buffer. A local attacker could possible use this to expose sensitive information.
(CVE-2020-0548)

It was discovered that on some Intel processors, data from the most recently evicted modified L1 data cache (L1D) line may be propagated into an unused (invalid) L1D fill buffer. A local attacker could possibly use this to expose sensitive information. (CVE-2020-0549).

Note that Tenable Network Security has extracted the preceding description block directly from the Ubuntu security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

Solution

Update the affected intel-microcode package.

See Also

https://ubuntu.com/security/notices/USN-4385-2

Plugin Details

Severity: Medium

ID: 137352

File Name: ubuntu_USN-4385-2.nasl

Version: 1.6

Type: local

Agent: unix

Published: 6/11/2020

Updated: 10/21/2023

Supported Sensors: Frictionless Assessment AWS, Frictionless Assessment Azure, Frictionless Assessment Agent, Nessus Agent, Agentless Assessment, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 4.4

CVSS v2

Risk Factor: Low

Base Score: 2.1

Temporal Score: 1.6

Vector: CVSS2#AV:L/AC:L/Au:N/C:P/I:N/A:N

CVSS Score Source: CVE-2020-0549

CVSS v3

Risk Factor: Medium

Base Score: 5.5

Temporal Score: 4.8

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:canonical:ubuntu_linux:18.04:-:lts, cpe:/o:canonical:ubuntu_linux:16.04:-:lts, cpe:/o:canonical:ubuntu_linux:20.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:intel-microcode

Required KB Items: Host/cpu, Host/Debian/dpkg-l, Host/Ubuntu, Host/Ubuntu/release

Exploit Ease: No known exploits are available

Patch Publication Date: 6/10/2020

Vulnerability Publication Date: 1/28/2020

Reference Information

CVE: CVE-2020-0543, CVE-2020-0548, CVE-2020-0549

USN: 4385-2