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CVE-2018-13405

Publication date 6 July 2018

Last updated 24 July 2024

Ubuntu priority

Medium

Why this priority?

Cvss 3 Severity Score

7.8 · High

Score breakdown

The inode_init_owner function in fs/inode.c in the Linux kernel through 3.16 allows local users to create files with an unintended group ownership, in a scenario where a directory is SGID to a certain group and is writable by a user who is not a member of that group. Here, the non-member can trigger creation of a plain file whose group ownership is that group. The intended behavior was that the non-member can trigger creation of a directory (but not a plain file) whose group ownership is that group. The non-member can escalate privileges by making the plain file executable and SGID.

From the Ubuntu Security Team

It was discovered that the Linux kernel did not properly handle setgid file creation when performed by a non-member of the group. A local attacker could use this to gain elevated privileges.

Read the notes from the security team

Status

Package Ubuntu Release Status
linux 18.10 cosmic
Not affected
18.04 LTS bionic
Fixed 4.15.0-33.36
17.10 artful Ignored
16.04 LTS xenial
Fixed 4.4.0-134.160
14.04 LTS trusty
Fixed 3.13.0-157.207
linux-aws 18.10 cosmic
Not affected
18.04 LTS bionic
Fixed 4.15.0-1020.20
17.10 artful Not in release
16.04 LTS xenial
Fixed 4.4.0-1066.76
14.04 LTS trusty
Fixed 4.4.0-1028.31
linux-azure 18.10 cosmic
Not affected
18.04 LTS bionic
Fixed 4.15.0-1022.23
17.10 artful Not in release
16.04 LTS xenial
Fixed 4.15.0-1022.22~16.04.1
14.04 LTS trusty
Not affected
linux-azure-edge 18.10 cosmic Not in release
18.04 LTS bionic
Not affected
17.10 artful Not in release
16.04 LTS xenial
Fixed 4.15.0-1022.23
14.04 LTS trusty Not in release
linux-euclid 18.10 cosmic Not in release
18.04 LTS bionic Not in release
17.10 artful Not in release
16.04 LTS xenial Ignored
14.04 LTS trusty Not in release
linux-flo 18.10 cosmic Not in release
18.04 LTS bionic Not in release
17.10 artful Not in release
16.04 LTS xenial Ignored
14.04 LTS trusty Not in release
linux-gcp 18.10 cosmic
Not affected
18.04 LTS bionic
Fixed 4.15.0-1018.19
17.10 artful Not in release
16.04 LTS xenial
Fixed 4.15.0-1018.19~16.04.2
14.04 LTS trusty Not in release
linux-gke 18.10 cosmic Not in release
18.04 LTS bionic Not in release
17.10 artful Not in release
16.04 LTS xenial Ignored
14.04 LTS trusty Not in release
linux-goldfish 18.10 cosmic Not in release
18.04 LTS bionic Not in release
17.10 artful Not in release
16.04 LTS xenial Ignored
14.04 LTS trusty Not in release
linux-grouper 18.10 cosmic Not in release
18.04 LTS bionic Not in release
17.10 artful Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-hwe 18.10 cosmic Not in release
18.04 LTS bionic
Not affected
17.10 artful Not in release
16.04 LTS xenial
Fixed 4.15.0-33.36~16.04.1
14.04 LTS trusty Not in release
linux-hwe-edge 18.10 cosmic Not in release
18.04 LTS bionic
Not affected
17.10 artful Not in release
16.04 LTS xenial
Fixed 4.15.0-33.36~16.04.1
14.04 LTS trusty Not in release
linux-kvm 18.10 cosmic
Not affected
18.04 LTS bionic
Fixed 4.15.0-1020.20
17.10 artful Not in release
16.04 LTS xenial
Fixed 4.4.0-1032.38
14.04 LTS trusty Not in release
linux-lts-trusty 18.10 cosmic Not in release
18.04 LTS bionic Not in release
17.10 artful Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-lts-utopic 18.10 cosmic Not in release
18.04 LTS bionic Not in release
17.10 artful Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-lts-vivid 18.10 cosmic Not in release
18.04 LTS bionic Not in release
17.10 artful Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-lts-wily 18.10 cosmic Not in release
18.04 LTS bionic Not in release
17.10 artful Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-lts-xenial 18.10 cosmic Not in release
18.04 LTS bionic Not in release
17.10 artful Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty
Fixed 4.4.0-134.160~14.04.1
linux-maguro 18.10 cosmic Not in release
18.04 LTS bionic Not in release
17.10 artful Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-mako 18.10 cosmic Not in release
18.04 LTS bionic Not in release
17.10 artful Not in release
16.04 LTS xenial Ignored
14.04 LTS trusty Not in release
linux-manta 18.10 cosmic Not in release
18.04 LTS bionic Not in release
17.10 artful Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-oem 18.10 cosmic
Not affected
18.04 LTS bionic
Fixed 4.15.0-1017.20
17.10 artful Not in release
16.04 LTS xenial Ignored
14.04 LTS trusty Not in release
linux-raspi2 18.10 cosmic
Not affected
18.04 LTS bionic
Fixed 4.15.0-1021.23
17.10 artful Ignored
16.04 LTS xenial
Fixed 4.4.0-1095.103
14.04 LTS trusty Not in release
linux-snapdragon 18.10 cosmic Not in release
18.04 LTS bionic
Not affected
17.10 artful Ignored
16.04 LTS xenial
Fixed 4.4.0-1099.104
14.04 LTS trusty Not in release

Notes

tyhicks

While inode_init_owner() has only been vulnerable since its introduction in a1bd120d13e586ea1c424048fd2c8420a442852a, this flaw has been present in individual filesystems since the beginning of the kernel git history.

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package Patch details
linux

Severity score breakdown

Parameter Value
Base score 7.8 · High
Attack vector Local
Attack complexity Low
Privileges required Low
User interaction None
Scope Unchanged
Confidentiality High
Integrity impact High
Availability impact High
Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

References

Related Ubuntu Security Notices (USN)

    • USN-3753-1
    • Linux kernel vulnerabilities
    • 24 August 2018
    • USN-3752-2
    • Linux kernel (HWE) vulnerabilities
    • 24 August 2018
    • USN-3752-1
    • Linux kernel vulnerabilities
    • 24 August 2018
    • USN-3753-2
    • Linux kernel (Xenial HWE) vulnerabilities
    • 24 August 2018
    • USN-3752-3
    • Linux kernel (Azure, GCP, OEM) vulnerabilities
    • 28 August 2018
    • USN-3754-1
    • Linux kernel vulnerabilities
    • 24 August 2018

Other references