SB2022082634 - Improper access control in Linux kernel

Description

This security bulletin contains information about 1 vulnerability.

1) Improper access control (CVE-ID: CVE-2021-3864)

CWE-ID: CWE-284 - Improper Access Control

CVSSv4: CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear

The vulnerability allows a local user to execute arbitrary code.

A flaw was found in the way the dumpable flag setting was handled when certain SUID binaries executed its descendants. The prerequisite is a SUID binary that sets real UID equal to effective UID, and real GID equal to effective GID. The descendant will then have a dumpable value set to 1. As a result, if the descendant process crashes and core_pattern is set to a relative value, its core dump is stored in the current directory with uid:gid permissions. An unprivileged local user with eligible root SUID binary could use this flaw to place core dumps into root-owned directories, potentially resulting in escalation of privileges.

Remediation

Install update from vendor's website.

References

• https://bugzilla.redhat.com/show_bug.cgi?id=2015046
• https://www.openwall.com/lists/oss-security/2021/10/20/2
• https://access.redhat.com/security/cve/CVE-2021-3864
• https://security-tracker.debian.org/tracker/CVE-2021-3864
• https://lore.kernel.org/all/20211221021744.864115-1-longman%40redhat.com/
• https://lore.kernel.org/lkml/20211228170910.623156-1-wander%40redhat.com/
• https://lore.kernel.org/all/20211226150310.GA992%401wt.eu/