Subject: [ASA-201902-6] runc: privilege escalation

Arch Linux Security Advisory ASA-201902-6
=========================================

Severity: High
Date    : 2019-02-11
CVE-ID  : CVE-2019-5736
Package : runc
Type    : privilege escalation
Remote  : Yes
Link    : https://security.archlinux.org/AVG-878

Summary
=======

The package runc before version 1.0.0rc6-1 is vulnerable to privilege
escalation.

Resolution
==========

Upgrade to 1.0.0rc6-1.

# pacman -Syu "runc>=1.0.0rc6-1"

The problem has been fixed upstream in version 1.0.0rc6.

Workaround
==========

Don't run privileged containers.

Description
===========

A vulnerability discovered in runc through 1.0-rc6, as used in Docker
before 18.09.2 and other products, allows attackers to overwrite the
host runc binary (and consequently obtain host root access) by
leveraging the ability to execute a command as root within one of these
types of containers: (1) a new container with an attacker-controlled
image, or (2) an existing container, to which the attacker previously
had write access, that can be attached with docker exec. This occurs
because of file-descriptor mishandling, related to /proc/self/exe.

Impact
======

A malicious container can escalate privileges to gain access as root on
the host system and execute arbitrary code.

References
==========

https://github.com/lxc/lxc/commit/6400238d08cdf1ca20d49bafb85f4e224348bf9d
https://github.com/opencontainers/runc/commit/0a8e4117e7f715d5fbeef398405813ce8e88558b
https://www.openwall.com/lists/oss-security/2019/02/11/2
https://security.archlinux.org/CVE-2019-5736