CVE-2018-13405

MEDIUM

Description

The inode_init_owner function in fs/inode.c in the Linux kernel through 4.17.4 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.

References

http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=0fa3ecd87848c9c93c2c828ef4c3a8ca36ce46c7

http://openwall.com/lists/oss-security/2018/07/13/2

http://www.securityfocus.com/bid/106503

https://access.redhat.com/errata/RHSA-2018:2948

https://access.redhat.com/errata/RHSA-2018:3083

https://access.redhat.com/errata/RHSA-2018:3096

https://github.com/torvalds/linux/commit/0fa3ecd87848c9c93c2c828ef4c3a8ca36ce46c7

https://lists.debian.org/debian-lts-announce/2018/08/msg00014.html

https://twitter.com/grsecurity/status/1015082951204327425

https://usn.ubuntu.com/3752-1/

https://usn.ubuntu.com/3752-2/

https://usn.ubuntu.com/3752-3/

https://usn.ubuntu.com/3753-1/

https://usn.ubuntu.com/3753-2/

https://usn.ubuntu.com/3754-1/

https://www.debian.org/security/2018/dsa-4266

https://www.exploit-db.com/exploits/45033/

Details

Source: MITRE

Published: 2018-07-06

Updated: 2019-01-10

Type: CWE-264

Risk Information

CVSS v2.0

Base Score: 4.6

Vector: AV:L/AC:L/Au:N/C:P/I:P/A:P

Impact Score: 6.4

Exploitability Score: 3.9

Severity: MEDIUM

CVSS v3.0

Base Score: 7.8

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Impact Score: 5.9

Exploitability Score: 1.8

Severity: HIGH