Privilege escalation in shadow

1) Permissions, Privileges, and Access Controls

EUVDB-ID: #VU23780

Risk: Low

CVSSv3.1: 8.1 [CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:U/RL:U/RC:C]

CVE-ID: CVE-2019-19882

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

Exploit availability: No

Description

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to missconfigured setuid programs in shadow 4.8 when compiled using --with-libpam but without explicitly passing --disable-account-tools-setuid, and without a PAM configuration suitable for use with setuid account management tools.. A local unprivileged user can leverage groupadd, groupdel, groupmod, useradd, userdel, or usermod management tools to escalate privileges on the system to root.

The issue affects at least Gentoo, Arch Linux, and Void Linux.

Mitigation

Install update from vendor's website.

Vulnerable software versions

shadow: 4.8

External links

http://bugs.archlinux.org/task/64836
http://bugs.gentoo.org/702252
http://github.com/shadow-maint/shadow/commit/edf7547ad5aa650be868cf2dac58944773c12d75
http://github.com/shadow-maint/shadow/pull/199
http://github.com/void-linux/void-packages/pull/17580

Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.