USN-4008-2: AppArmor update
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
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
ubuntu/apparmor-profilesto a version that resolves this vulnerability.Fixed in 2.10.95-0ubuntu2.11 - Upgrade
Upgrade
ubuntu/python3-apparmorto a version that resolves this vulnerability.Fixed in 2.10.95-0ubuntu2.11 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Patch USN-4008-1 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Patch USN-4008-2 - Configuration
Disable a.out support as a hardening measure.
Linux kernel a.out support = disabled - Configuration
Ensure the RDS protocol remains disabled via the Ubuntu blocklist.
Linux kernel RDS protocol blocklist = disabled
Event History
Frequently Asked Questions
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.
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.
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.