Ubuntu update for Linux kernel (HWE)

Published: 2019-03-05 | Updated: 2019-03-18

Risk	Low
Patch available	YES
Number of vulnerabilities	3
CVE-ID	CVE-2018-18397 CVE-2018-19854 CVE-2019-6133
CWE-ID	CWE-264 CWE-401
Exploitation vector	Network
Public exploit	Public exploit code for vulnerability #1 is available. Public exploit code for vulnerability #2 is available. Public exploit code for vulnerability #3 is available.
Vulnerable software Subscribe	linux-azure (Ubuntu package) Operating systems & Components / Operating system package or component linux-gcp (Ubuntu package) Operating systems & Components / Operating system package or component linux-aws-hwe (Ubuntu package) Operating systems & Components / Operating system package or component linux-oracle (Ubuntu package) Operating systems & Components / Operating system package or component
Vendor	Canonical Ltd.

Security Bulletin

This security bulletin contains information about 3 vulnerabilities.

1) Security restrictions bypass

EUVDB-ID: #VU16558

Risk: Low

CVSSv3.1: 4.8 [CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L/E:P/RL:O/RC:C]

CVE-ID: CVE-2018-18397

CWE-ID: CWE-264 - Permissions, Privileges, and Access Controls

Exploit availability: Yes

Description

The vulnerability allows a local attacker to bypass security restrictions on the target system.

The vulnerability exists due to improper access control in the userfaultfd implementation. A local attacker can access a system that is mounted with shmem or hugetlbs virtual memory areas, maliciously modify mapping to targeted files and write arbitrary memory on the system, which could be used to conduct additional attacks.

Mitigation

Update the affected packages.

Ubuntu 16.04 LTS: linux-image-4.15.0-1009-oracle - 4.15.0-1009.11~16.04.1; linux-image-4.15.0-1028-gcp - 4.15.0-1028.29~16.04.1; linux-image-4.15.0-1033-aws - 4.15.0-1033.35~16.04.1; linux-image-4.15.0-1040-azure - 4.15.0-1040.44; linux-image-4.15.0-46-generic - 4.15.0-46.49~16.04.1; linux-image-4.15.0-46-generic-lpae - 4.15.0-46.49~16.04.1; linux-image-4.15.0-46-lowlatency - 4.15.0-46.49~16.04.1; linux-image-aws-hwe - 4.15.0.1033.34; linux-image-azure - 4.15.0.1040.44; linux-image-gcp - 4.15.0.1028.42; linux-image-generic-hwe-16.04 - 4.15.0.46.67; linux-image-generic-lpae-hwe-16.04 - 4.15.0.46.67; linux-image-gke - 4.15.0.1028.42; linux-image-lowlatency-hwe-16.04 - 4.15.0.46.67; linux-image-oem - 4.15.0.46.67; linux-image-oracle - 4.15.0.1009.3
Ubuntu 14.04 LTS: linux-image-4.15.0-1040-azure - 4.15.0-1040.44~14.04.1; linux-image-azure - 4.15.0.1040.27

Vulnerable software versions

linux-azure (Ubuntu package): 4.15.0-1000.0 - 4.15.0-1039.43

linux-gcp (Ubuntu package): 4.15.0-1010.10~16.04.1 - 4.15.0-1027.28~16.04.1

linux-aws-hwe (Ubuntu package): 4.15.0-1030.31~16.04.1 - 4.15.0-1032.34~16.04.1

linux-oracle (Ubuntu package): 4.15.0-1006.6~16.04.1 - 4.15.0-1008.10~16.04.1

External links

http://usn.ubuntu.com/3901-2/

Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, proof of concept for this vulnerability is available.

2) Memory leak

EUVDB-ID: #VU17257

Risk: Low

CVSSv3.1: 3 [CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N/E:P/RL:O/RC:C]

CVE-ID: CVE-2018-19854

CWE-ID: CWE-401 - Missing release of memory after effective lifetime

Exploit availability: No

Description

The vulnerability allows a local attacker to perform DoS attack on the target system.

The vulnerability exists due to crypto_report_one() and related functions in crypto/crypto_user.c (the crypto user configuration API) do not fully initialize structures that are copied to userspace. A local attacker can trigger memory leak and perform denial of service attack.

Mitigation

Update the affected packages.

Ubuntu 16.04 LTS: linux-image-4.15.0-1009-oracle - 4.15.0-1009.11~16.04.1; linux-image-4.15.0-1028-gcp - 4.15.0-1028.29~16.04.1; linux-image-4.15.0-1033-aws - 4.15.0-1033.35~16.04.1; linux-image-4.15.0-1040-azure - 4.15.0-1040.44; linux-image-4.15.0-46-generic - 4.15.0-46.49~16.04.1; linux-image-4.15.0-46-generic-lpae - 4.15.0-46.49~16.04.1; linux-image-4.15.0-46-lowlatency - 4.15.0-46.49~16.04.1; linux-image-aws-hwe - 4.15.0.1033.34; linux-image-azure - 4.15.0.1040.44; linux-image-gcp - 4.15.0.1028.42; linux-image-generic-hwe-16.04 - 4.15.0.46.67; linux-image-generic-lpae-hwe-16.04 - 4.15.0.46.67; linux-image-gke - 4.15.0.1028.42; linux-image-lowlatency-hwe-16.04 - 4.15.0.46.67; linux-image-oem - 4.15.0.46.67; linux-image-oracle - 4.15.0.1009.3
Ubuntu 14.04 LTS: linux-image-4.15.0-1040-azure - 4.15.0-1040.44~14.04.1; linux-image-azure - 4.15.0.1040.27

Vulnerable software versions

linux-azure (Ubuntu package): 4.15.0-1000.0 - 4.15.0-1039.43

linux-gcp (Ubuntu package): 4.15.0-1010.10~16.04.1 - 4.15.0-1027.28~16.04.1

linux-aws-hwe (Ubuntu package): 4.15.0-1030.31~16.04.1 - 4.15.0-1032.34~16.04.1

linux-oracle (Ubuntu package): 4.15.0-1006.6~16.04.1 - 4.15.0-1008.10~16.04.1

External links

http://usn.ubuntu.com/3901-2/

Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, proof of concept for this vulnerability is available.

3) Security restrictions bypass

EUVDB-ID: #VU16966

Risk: Low

CVSSv3.1: 6.9 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L/E:P/RL:U/RC:C]

CVE-ID: CVE-2019-6133

CWE-ID: CWE-264 - Permissions, Privileges, and Access Controls

Exploit availability: No

Description

The vulnerability allows a remote attacker to bypass security restrictions on the target system.

The vulnerability exists due to fork() is not atomic, and therefore authorization decisions are improperly cached, related to lack of uid checking in polkitbackend/polkitbackendinteractiveauthority.c. A remote unauthenticated attacker can bypass the "start time" protection mechanism

Mitigation

Update the affected packages.

Ubuntu 16.04 LTS: linux-image-4.15.0-1009-oracle - 4.15.0-1009.11~16.04.1; linux-image-4.15.0-1028-gcp - 4.15.0-1028.29~16.04.1; linux-image-4.15.0-1033-aws - 4.15.0-1033.35~16.04.1; linux-image-4.15.0-1040-azure - 4.15.0-1040.44; linux-image-4.15.0-46-generic - 4.15.0-46.49~16.04.1; linux-image-4.15.0-46-generic-lpae - 4.15.0-46.49~16.04.1; linux-image-4.15.0-46-lowlatency - 4.15.0-46.49~16.04.1; linux-image-aws-hwe - 4.15.0.1033.34; linux-image-azure - 4.15.0.1040.44; linux-image-gcp - 4.15.0.1028.42; linux-image-generic-hwe-16.04 - 4.15.0.46.67; linux-image-generic-lpae-hwe-16.04 - 4.15.0.46.67; linux-image-gke - 4.15.0.1028.42; linux-image-lowlatency-hwe-16.04 - 4.15.0.46.67; linux-image-oem - 4.15.0.46.67; linux-image-oracle - 4.15.0.1009.3
Ubuntu 14.04 LTS: linux-image-4.15.0-1040-azure - 4.15.0-1040.44~14.04.1; linux-image-azure - 4.15.0.1040.27

Vulnerable software versions

linux-azure (Ubuntu package): 4.15.0-1000.0 - 4.15.0-1039.43

linux-gcp (Ubuntu package): 4.15.0-1010.10~16.04.1 - 4.15.0-1027.28~16.04.1

linux-aws-hwe (Ubuntu package): 4.15.0-1030.31~16.04.1 - 4.15.0-1032.34~16.04.1

linux-oracle (Ubuntu package): 4.15.0-1006.6~16.04.1 - 4.15.0-1008.10~16.04.1

External links

http://usn.ubuntu.com/3901-2/

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, proof of concept for this vulnerability is available.