Permissions, Privileges, and Access Controls in Linux kernel

1) Permissions, Privileges, and Access Controls

EUVDB-ID: #VU41049

Risk: Medium

CVSSv3.1: 5.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L/E:U/RL:O/RC:C]

CVE-ID: CVE-2014-8989

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

Exploit availability: No

Description

The vulnerability allows a remote non-authenticated attacker to read and manipulate data.

The Linux kernel through 3.17.4 does not properly restrict dropping of supplemental group memberships in certain namespace scenarios, which allows local users to bypass intended file permissions by leveraging a POSIX ACL containing an entry for the group category that is more restrictive than the entry for the other category, aka a "negative groups" issue, related to kernel/groups.c, kernel/uid16.c, and kernel/user_namespace.c.

Mitigation

Install update from vendor's website.

Vulnerable software versions

Linux kernel: 3.0 - 3.17.2

External links

http://lists.fedoraproject.org/pipermail/package-announce/2015-January/147864.html
http://lists.fedoraproject.org/pipermail/package-announce/2015-January/147973.html
http://thread.gmane.org/gmane.linux.man/7385/
http://www.mandriva.com/security/advisories?name=MDVSA-2015:058
http://www.openwall.com/lists/oss-security/2014/11/20/4
http://www.securityfocus.com/bid/71154
http://www.ubuntu.com/usn/USN-2515-1
http://www.ubuntu.com/usn/USN-2516-1
http://www.ubuntu.com/usn/USN-2517-1
http://www.ubuntu.com/usn/USN-2518-1

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.