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             AUSCERT External Security Bulletin Redistribution

                  USN-4385-2: Intel Microcode regression
                               11 June 2020


        AusCERT Security Bulletin Summary

Product:           Intel Microcode
Publisher:         Ubuntu
Operating System:  Ubuntu
Impact/Access:     Access Privileged Data -- Existing Account
Resolution:        Patch/Upgrade
CVE Names:         CVE-2020-0549 CVE-2020-0548 CVE-2020-0543

Reference:         ESB-2020.2011

Original Bulletin: 

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USN-4385-2: Intel Microcode regression
10 June 2020

intel-microcode regression
A security issue affects these releases of Ubuntu and its derivatives:

  o Ubuntu 20.04 LTS
  o Ubuntu 19.10
  o Ubuntu 18.04 LTS
  o Ubuntu 16.04 LTS
  o Ubuntu 14.04 ESM


USN-4385-1 introduced a regression in the Intel Microcode for some processors.

Software Description

  o intel-microcode - Processor microcode for Intel CPUs


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.

Original advisory details:

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)

Update instructions

The problem can be corrected by updating your system to the following package

Ubuntu 20.04 LTS
    intel-microcode - 3.20200609.0ubuntu0.20.04.2
Ubuntu 19.10
    intel-microcode - 3.20200609.0ubuntu0.19.10.2
Ubuntu 18.04 LTS
    intel-microcode - 3.20200609.0ubuntu0.18.04.1
Ubuntu 16.04 LTS
    intel-microcode - 3.20200609.0ubuntu0.16.04.1
Ubuntu 14.04 ESM
    intel-microcode - 3.20200609.0ubuntu0.14.04.1

To update your system, please follow these instructions: https://
wiki.ubuntu.com/Security/Upgrades .

After a standard system update you need to reboot your computer to make all the
necessary changes.


  o USN-4385-1
  o LP: 1882890
  o LP: 1883002

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