USN-4008-2: AppArmor update

Published Jun 5, 2019
·
Updated

USN-4008-1 fixed multiple security issues in the Linux kernel. This update provides the corresponding changes to AppArmor policy for correctly operating under the Linux kernel with fixes for CVE-2019-11190. Without these changes, some profile transitions may be unintentionally denied due to missing mmap ('m') rules. Original advisory details: Robert Święcki discovered that the Linux kernel did not properly apply Address Space Layout Randomization (ASLR) in some situations for setuid elf binaries. A local attacker could use this to improve the chances of exploiting an existing vulnerability in a setuid elf binary. (CVE-2019-11190) It was discovered that a null pointer dereference vulnerability existed in the LSI Logic MegaRAID driver in the Linux kernel. A local attacker could use this to cause a denial of service (system crash). (CVE-2019-11810) It was discovered that a race condition leading to a use-after-free existed in the Reliable Datagram Sockets (RDS) protocol implementation in the Linux kernel. The RDS protocol is disabled via blocklist by default in Ubuntu. If enabled, a local attacker could use this to cause a denial of service (system crash) or possibly execute arbitrary code. (CVE-2019-11815) 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. (CVE-2019-11191) As a hardening measure, this update disables a.out support.

Affected Software

5 affected componentsFixes available
Canonical Apparmor
All of the following
ubuntu/apparmor-profiles<2.10.95-0ubuntu2.11
2.10.95-0ubuntu2.11
Ubuntu Ubuntu=16.04
All of the following
ubuntu/python3-apparmor<2.10.95-0ubuntu2.11
2.10.95-0ubuntu2.11
Ubuntu Ubuntu=16.04

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade ubuntu/apparmor-profiles to a version that resolves this vulnerability.

    Fixed in 2.10.95-0ubuntu2.11
  2. Upgrade

    Upgrade ubuntu/python3-apparmor to a version that resolves this vulnerability.

    Fixed in 2.10.95-0ubuntu2.11
  3. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Patch USN-4008-1
  4. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Patch USN-4008-2
  5. Configuration

    Disable a.out support as a hardening measure.

    Linux kernel a.out support = disabled
  6. Configuration

    Ensure the RDS protocol remains disabled via the Ubuntu blocklist.

    Linux kernel RDS protocol blocklist = disabled

Event History

Jun 5, 2019
Advisory Published
via Ubuntu·12:00 AM
Data Sourced
via Ubuntu·12:00 AM
DescriptionAffected Software

Child vulnerabilities

Contains the following vulnerabilities.

Frequently Asked Questions

1

What is the operational impact of not applying this AppArmor policy update?

Systems running the Linux kernel changes for CVE-2019-11190 may have some AppArmor profile transitions unintentionally denied because required mmap ('m') rules are missing.

2

Are systems using the RDS protocol exposed by default?

No. The RDS protocol is blocklisted by default in Ubuntu. The RDS-related risk applies if the protocol has been enabled.

3

What level of access does an attacker need for the kernel issues described?

The described ASLR, MegaRAID driver, and RDS issues require a local attacker. Exploiting the ASLR issue also depends on an existing vulnerability in a setuid ELF binary.

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