Your submission was sent successfully! Close

You have successfully unsubscribed! Close

Thank you for signing up for our newsletter!
In these regular emails you will find the latest updates about Ubuntu and upcoming events where you can meet our team.Close

CVE-2018-13405

Published: 6 July 2018

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.

Notes

AuthorNote
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.

Priority

Medium

Cvss 3 Severity Score

7.8

Score breakdown

Status

Package Release Status
linux-aws
Launchpad, Ubuntu, Debian
artful Does not exist

bionic
Released (4.15.0-1020.20)
cosmic Not vulnerable
(4.15.0-1020.20)
trusty
Released (4.4.0-1028.31)
upstream
Released (4.18~rc4)
xenial
Released (4.4.0-1066.76)
linux-azure
Launchpad, Ubuntu, Debian
artful Does not exist

bionic
Released (4.15.0-1022.23)
cosmic Not vulnerable
(4.18.0-1003.3)
trusty Not vulnerable
(4.15.0-1023.24~14.04.1)
upstream
Released (4.18~rc4)
xenial
Released (4.15.0-1022.22~16.04.1)
linux-euclid
Launchpad, Ubuntu, Debian
artful Does not exist

bionic Does not exist

cosmic Does not exist

trusty Does not exist

upstream
Released (4.18~rc4)
xenial Ignored
(was needed ESM criteria)
linux-kvm
Launchpad, Ubuntu, Debian
artful Does not exist

bionic
Released (4.15.0-1020.20)
cosmic Not vulnerable
(4.15.0-1020.20)
trusty Does not exist

upstream
Released (4.18~rc4)
xenial
Released (4.4.0-1032.38)
linux
Launchpad, Ubuntu, Debian
artful Ignored
(end of life)
bionic
Released (4.15.0-33.36)
cosmic Not vulnerable
(4.17.0-6.7)
trusty
Released (3.13.0-157.207)
upstream
Released (4.18~rc4)
xenial
Released (4.4.0-134.160)
Patches:
Introduced by

1da177e4c3f41524e886b7f1b8a0c1fc7321cac2

Fixed by 0fa3ecd87848c9c93c2c828ef4c3a8ca36ce46c7
linux-azure-edge
Launchpad, Ubuntu, Debian
artful Does not exist

bionic Not vulnerable
(4.18.0-1003.3~18.04.1)
cosmic Does not exist

trusty Does not exist

upstream
Released (4.18~rc4)
xenial
Released (4.15.0-1022.23)
linux-flo
Launchpad, Ubuntu, Debian
artful Does not exist

bionic Does not exist

cosmic Does not exist

trusty Does not exist
(trusty was ignored [abandoned])
upstream
Released (4.18~rc4)
xenial Ignored
(abandoned)
linux-gcp
Launchpad, Ubuntu, Debian
artful Does not exist

bionic
Released (4.15.0-1018.19)
cosmic Not vulnerable
(4.15.0-1018.19)
trusty Does not exist

upstream
Released (4.18~rc4)
xenial
Released (4.15.0-1018.19~16.04.2)
linux-gke
Launchpad, Ubuntu, Debian
artful Does not exist

bionic Does not exist

cosmic Does not exist

trusty Does not exist

upstream
Released (4.18~rc4)
xenial Ignored
(end of standard support)
linux-goldfish
Launchpad, Ubuntu, Debian
artful Does not exist

bionic Does not exist

cosmic Does not exist

trusty Does not exist
(trusty was ignored [abandoned])
upstream
Released (4.18~rc4)
xenial Ignored
(end of life)
linux-grouper
Launchpad, Ubuntu, Debian
artful Does not exist

bionic Does not exist

cosmic Does not exist

trusty Does not exist
(trusty was ignored [abandoned])
upstream
Released (4.18~rc4)
xenial Does not exist

linux-hwe
Launchpad, Ubuntu, Debian
artful Does not exist

bionic Not vulnerable

cosmic Does not exist

trusty Does not exist

upstream
Released (4.18~rc4)
xenial
Released (4.15.0-33.36~16.04.1)
linux-hwe-edge
Launchpad, Ubuntu, Debian
artful Does not exist

bionic Not vulnerable
(4.18.0-11.12~18.04.1)
cosmic Does not exist

trusty Does not exist

upstream
Released (4.18~rc4)
xenial
Released (4.15.0-33.36~16.04.1)
linux-lts-trusty
Launchpad, Ubuntu, Debian
artful Does not exist

bionic Does not exist

cosmic Does not exist

trusty Does not exist

upstream
Released (4.18~rc4)
xenial Does not exist

linux-lts-utopic
Launchpad, Ubuntu, Debian
artful Does not exist

bionic Does not exist

cosmic Does not exist

trusty Does not exist
(trusty was ignored [end of standard support])
upstream
Released (4.18~rc4)
xenial Does not exist

linux-lts-vivid
Launchpad, Ubuntu, Debian
artful Does not exist

bionic Does not exist

cosmic Does not exist

trusty Does not exist
(trusty was ignored [end of standard support])
upstream
Released (4.18~rc4)
xenial Does not exist

linux-lts-wily
Launchpad, Ubuntu, Debian
artful Does not exist

bionic Does not exist

cosmic Does not exist

trusty Does not exist
(trusty was ignored [end of standard support])
upstream
Released (4.18~rc4)
xenial Does not exist

linux-lts-xenial
Launchpad, Ubuntu, Debian
artful Does not exist

bionic Does not exist

cosmic Does not exist

trusty
Released (4.4.0-134.160~14.04.1)
upstream
Released (4.18~rc4)
xenial Does not exist

linux-maguro
Launchpad, Ubuntu, Debian
artful Does not exist

bionic Does not exist

cosmic Does not exist

trusty Does not exist
(trusty was ignored [abandoned])
upstream
Released (4.18~rc4)
xenial Does not exist

linux-mako
Launchpad, Ubuntu, Debian
artful Does not exist

bionic Does not exist

cosmic Does not exist

trusty Does not exist
(trusty was ignored [abandoned])
upstream
Released (4.18~rc4)
xenial Ignored
(abandoned)
linux-manta
Launchpad, Ubuntu, Debian
artful Does not exist

bionic Does not exist

cosmic Does not exist

trusty Does not exist
(trusty was ignored [abandoned])
upstream
Released (4.18~rc4)
xenial Does not exist

linux-oem
Launchpad, Ubuntu, Debian
artful Does not exist

bionic
Released (4.15.0-1017.20)
cosmic Not vulnerable
(4.15.0-1017.20)
trusty Does not exist

upstream
Released (4.18~rc4)
xenial Ignored
(end of standard support, was needed)
linux-raspi2
Launchpad, Ubuntu, Debian
artful Ignored
(end of life)
bionic
Released (4.15.0-1021.23)
cosmic Not vulnerable
(4.15.0-1021.23)
trusty Does not exist

upstream
Released (4.18~rc4)
xenial
Released (4.4.0-1095.103)
linux-snapdragon
Launchpad, Ubuntu, Debian
artful Ignored
(end of life)
bionic Not vulnerable

cosmic Does not exist

trusty Does not exist

upstream
Released (4.18~rc4)
xenial
Released (4.4.0-1099.104)

Severity score breakdown

Parameter Value
Base score 7.8
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