Privilege escalation in containerd

1) Security restrictions bypass

EUVDB-ID: #VU59237

Risk: Low

CVSSv3.1: 7.3 [CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-43816

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 a logic issue, which causes arbitrary files and directories on the host to be relabeled to match the container process label through the use of specially-configured bind mounts in a hostPath volume. A local user can place the in-container location of the hostPath volume mount at either `/etc/hosts`, `/etc/hostname`, or `/etc/resolv.conf` and gain read/write access to arbitrary file on the system.

The vulnerability affects containerd installations using SELinux, such as EL8 (CentOS, RHEL), Fedora, or SUSE MicroOS.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

containerd: 1.5.0 - 1.5.8

External links

http://github.com/containerd/containerd/security/advisories/GHSA-mvff-h3cj-wj9c

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.