Ubuntu 18.10: USN-4006-1 Critical: Linux Kernel ASLR Bypass

ubuntu

June 4, 2019

A system hardening measure could be bypassed.

Summary

A system hardening measure could be bypassed.

Software Description:

- linux: Linux kernel

- linux-aws: Linux kernel for Amazon Web Services (AWS) systems

- linux-gcp: Linux kernel for Google Cloud Platform (GCP) systems

- linux-kvm: Linux kernel for cloud environments

- linux-raspi2: Linux kernel for Raspberry Pi 2

Details:

Federico Manuel Bento discovered that the Linux kernel did not properly

apply Address Space Layout Randomization (ASLR) in some situations for

setuid a.out binaries. A local attacker could use this to improve the

chances of exploiting an existing vulnerability in a setuid a.out binary.

As a hardening measure, this update disables a.out support.

Topics Covered

security advisory Ubuntu exploitation linux kernel system reboot update instruction ASLR

Update Instructions

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

Ubuntu 18.10:
  linux-image-4.18.0-1012-gcp     4.18.0-1012.13
  linux-image-4.18.0-1013-kvm     4.18.0-1013.13
  linux-image-4.18.0-1015-raspi2  4.18.0-1015.17
  linux-image-4.18.0-1017-aws     4.18.0-1017.19
  linux-image-4.18.0-21-generic   4.18.0-21.22
  linux-image-4.18.0-21-generic-lpae  4.18.0-21.22
  linux-image-4.18.0-21-lowlatency  4.18.0-21.22
  linux-image-4.18.0-21-snapdragon  4.18.0-21.22
  linux-image-aws                 4.18.0.1017.17
  linux-image-gcp                 4.18.0.1012.12
  linux-image-generic             4.18.0.21.22
  linux-image-generic-lpae        4.18.0.21.22
  linux-image-gke                 4.18.0.1012.12
  linux-image-kvm                 4.18.0.1013.13
  linux-image-lowlatency          4.18.0.21.22
  linux-image-raspi2              4.18.0.1015.12
  linux-image-snapdragon          4.18.0.21.22

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

ATTENTION: Due to an unavoidable ABI change the kernel updates have
been given a new version number, which requires you to recompile and
reinstall all third party kernel modules you might have installed.
Unless you manually uninstalled the standard kernel metapackages
(e.g. linux-generic, linux-generic-lts-RELEASE, linux-virtual,
linux-powerpc), a standard system upgrade will automatically perform
this as well.